diff --git a/drivers/staging/erofs/Kconfig b/drivers/staging/erofs/Kconfig
index 663b755bf2fb..74b0aaa7114c 100644
--- a/drivers/staging/erofs/Kconfig
+++ b/drivers/staging/erofs/Kconfig
@@ -1,19 +1,20 @@
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: GPL-2.0-only
 
 config EROFS_FS
 	tristate "EROFS filesystem support"
 	depends on BLOCK
+	select LIBCRC32C
 	help
-	  EROFS(Enhanced Read-Only File System) is a lightweight
+	  EROFS (Enhanced Read-Only File System) is a lightweight
 	  read-only file system with modern designs (eg. page-sized
 	  blocks, inline xattrs/data, etc.) for scenarios which need
-	  high-performance read-only requirements, eg. firmwares in
-	  mobile phone or LIVECDs.
+	  high-performance read-only requirements, e.g. Android OS
+	  for mobile phones and LIVECDs.
 
-	  It also provides VLE compression support, focusing on
-	  random read improvements, keeping relatively lower
-	  compression ratios, which is useful for high-performance
-	  devices with limited memory and ROM space.
+	  It also provides fixed-sized output compression support,
+	  which improves storage density, keeps relatively higher
+	  compression ratios, which is more useful to achieve high
+	  performance for embedded devices with limited memory.
 
 	  If unsure, say N.
 
@@ -21,8 +22,9 @@ config EROFS_FS_DEBUG
 	bool "EROFS debugging feature"
 	depends on EROFS_FS
 	help
-	  Print EROFS debugging messages and enable more BUG_ONs
-	  which check the filesystem consistency aggressively.
+	  Print debugging messages and enable more BUG_ONs which check
+	  filesystem consistency and find potential issues aggressively,
+	  which can be used for Android eng build, for example.
 
 	  For daily use, say N.
 
@@ -54,6 +56,7 @@ config EROFS_FS_POSIX_ACL
 config EROFS_FS_SECURITY
 	bool "EROFS Security Labels"
 	depends on EROFS_FS_XATTR
+	default y
 	help
 	  Security labels provide an access control facility to support Linux
 	  Security Models (LSMs) accepted by AppArmor, SELinux, Smack and TOMOYO
@@ -63,29 +66,15 @@ config EROFS_FS_SECURITY
 
 	  If you are not using a security module, say N.
 
-config EROFS_FS_USE_VM_MAP_RAM
-	bool "EROFS VM_MAP_RAM Support"
-	depends on EROFS_FS
-	help
-	  use vm_map_ram/vm_unmap_ram instead of vmap/vunmap.
-
-	  If you don't know what these are, say N.
-
-config EROFS_FAULT_INJECTION
-	bool "EROFS fault injection facility"
-	depends on EROFS_FS
-	help
-	  Test EROFS to inject faults such as ENOMEM, EIO, and so on.
-	  If unsure, say N.
-
 config EROFS_FS_ZIP
-	bool "EROFS Data Compresssion Support"
+	bool "EROFS Data Compression Support"
 	depends on EROFS_FS
+	select LZ4_DECOMPRESS
+	default y
 	help
-	  Currently we support VLE Compression only.
-	  Play at your own risk.
+	  Enable fixed-sized output compression for EROFS.
 
-	  If you don't want to use compression feature, say N.
+	  If you don't want to enable compression feature, say N.
 
 config EROFS_FS_CLUSTER_PAGE_LIMIT
 	int "EROFS Cluster Pages Hard Limit"
@@ -93,49 +82,11 @@ config EROFS_FS_CLUSTER_PAGE_LIMIT
 	range 1 256
 	default "1"
 	help
-	  Indicates VLE compressed pages hard limit of a
-	  compressed cluster.
-
-	  For example, if files of a image are compressed
-	  into 8k-unit, the hard limit should not be less
-	  than 2. Otherwise, the image cannot be mounted
-	  correctly on this kernel.
-
-choice
-	prompt "EROFS VLE Data Decompression mode"
-	depends on EROFS_FS_ZIP
-	default EROFS_FS_ZIP_CACHE_BIPOLAR
-	help
-	  EROFS supports three options for VLE decompression.
-	  "In-place Decompression Only" consumes the minimum memory
-	  with lowest random read.
-
-	  "Bipolar Cached Decompression" consumes the maximum memory
-	  with highest random read.
-
-	  If unsure, select "Bipolar Cached Decompression"
-
-config EROFS_FS_ZIP_NO_CACHE
-	bool "In-place Decompression Only"
-	help
-	  Read compressed data into page cache and do in-place
-	  decompression directly.
-
-config EROFS_FS_ZIP_CACHE_UNIPOLAR
-	bool "Unipolar Cached Decompression"
-	help
-	  For each request, it caches the last compressed page
-	  for further reading.
-	  It still decompresses in place for the rest compressed pages.
-
-config EROFS_FS_ZIP_CACHE_BIPOLAR
-	bool "Bipolar Cached Decompression"
-	help
-	  For each request, it caches the both end compressed pages
-	  for further reading.
-	  It still decompresses in place for the rest compressed pages.
-
-	  Recommended for performance priority.
+	  Indicates maximum # of pages of a compressed
+	  physical cluster.
 
-endchoice
+	  For example, if files in a image were compressed
+	  into 8k-unit, hard limit should not be configured
+	  less than 2. Otherwise, the image will be refused
+	  to mount on this kernel.
 
diff --git a/drivers/staging/erofs/Makefile b/drivers/staging/erofs/Makefile
index 9a766eb7ed75..46f2aa4ba46c 100644
--- a/drivers/staging/erofs/Makefile
+++ b/drivers/staging/erofs/Makefile
@@ -1,13 +1,11 @@
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: GPL-2.0-only
 
-EROFS_VERSION = "1.0pre1"
+EROFS_VERSION = "1.0"
 
-ccflags-y += -Wall -DEROFS_VERSION=\"$(EROFS_VERSION)\"
+ccflags-y += -DEROFS_VERSION=\"$(EROFS_VERSION)\"
 
 obj-$(CONFIG_EROFS_FS) += erofs.o
-# staging requirement: to be self-contained in its own directory
-ccflags-y += -I$(src)/include
 erofs-objs := super.o inode.o data.o namei.o dir.o utils.o
 erofs-$(CONFIG_EROFS_FS_XATTR) += xattr.o
-erofs-$(CONFIG_EROFS_FS_ZIP) += unzip_vle.o unzip_lz4.o unzip_vle_lz4.o
+erofs-$(CONFIG_EROFS_FS_ZIP) += decompressor.o zmap.o zdata.o
 
diff --git a/drivers/staging/erofs/compress.h b/drivers/staging/erofs/compress.h
new file mode 100644
index 000000000000..e9b1aa0afe0e
--- /dev/null
+++ b/drivers/staging/erofs/compress.h
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2019 HUAWEI, Inc.
+ *             https://www.huawei.com/
+ */
+#ifndef __EROFS_FS_COMPRESS_H
+#define __EROFS_FS_COMPRESS_H
+
+#include "internal.h"
+
+enum {
+	Z_EROFS_COMPRESSION_SHIFTED = Z_EROFS_COMPRESSION_MAX,
+	Z_EROFS_COMPRESSION_RUNTIME_MAX
+};
+
+struct z_erofs_decompress_req {
+	struct super_block *sb;
+	struct page **in, **out;
+
+	unsigned short pageofs_out;
+	unsigned int inputsize, outputsize;
+
+	/* indicate the algorithm will be used for decompression */
+	unsigned int alg;
+	bool inplace_io, partial_decoding;
+};
+
+/*
+ * - 0x5A110C8D ('sallocated', Z_EROFS_MAPPING_STAGING) -
+ * used to mark temporary allocated pages from other
+ * file/cached pages and NULL mapping pages.
+ */
+#define Z_EROFS_MAPPING_STAGING         ((void *)0x5A110C8D)
+
+/* check if a page is marked as staging */
+static inline bool z_erofs_page_is_staging(struct page *page)
+{
+	return page->mapping == Z_EROFS_MAPPING_STAGING;
+}
+
+static inline bool z_erofs_put_stagingpage(struct list_head *pagepool,
+					   struct page *page)
+{
+	if (!z_erofs_page_is_staging(page))
+		return false;
+
+	/* staging pages should not be used by others at the same time */
+	if (page_ref_count(page) > 1)
+		put_page(page);
+	else
+		list_add(&page->lru, pagepool);
+	return true;
+}
+
+int z_erofs_decompress(struct z_erofs_decompress_req *rq,
+		       struct list_head *pagepool);
+
+#endif
diff --git a/drivers/staging/erofs/data.c b/drivers/staging/erofs/data.c
index 894e60ecebe2..4f305b68497e 100644
--- a/drivers/staging/erofs/data.c
+++ b/drivers/staging/erofs/data.c
@@ -1,21 +1,14 @@
-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
- * linux/drivers/staging/erofs/data.c
- *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
+ *             https://www.huawei.com/
  */
 #include "internal.h"
 #include <linux/prefetch.h>
 
 #include <trace/events/erofs.h>
 
-static inline void read_endio(struct bio *bio)
+static void erofs_readendio(struct bio *bio)
 {
 	int i;
 	struct bio_vec *bvec;
@@ -27,7 +20,7 @@ static inline void read_endio(struct bio *bio)
 		/* page is already locked */
 		DBG_BUGON(PageUptodate(page));
 
-		if (unlikely(err))
+		if (err)
 			SetPageError(page);
 		else
 			SetPageUptodate(page);
@@ -38,70 +31,35 @@ static inline void read_endio(struct bio *bio)
 	bio_put(bio);
 }
 
-/* prio -- true is used for dir */
-struct page *erofs_get_meta_page(struct super_block *sb,
-	erofs_blk_t blkaddr, bool prio)
+struct page *erofs_get_meta_page(struct super_block *sb, erofs_blk_t blkaddr)
 {
-	struct inode *bd_inode = sb->s_bdev->bd_inode;
-	struct address_space *mapping = bd_inode->i_mapping;
+	struct address_space *const mapping = sb->s_bdev->bd_inode->i_mapping;
 	struct page *page;
 
-repeat:
-	page = find_or_create_page(mapping, blkaddr,
-	/*
-	 * Prefer looping in the allocator rather than here,
-	 * at least that code knows what it's doing.
-	 */
-		mapping_gfp_constraint(mapping, ~__GFP_FS) | __GFP_NOFAIL);
-
-	BUG_ON(!page || !PageLocked(page));
-
-	if (!PageUptodate(page)) {
-		struct bio *bio;
-		int err;
-
-		bio = prepare_bio(sb, blkaddr, 1, read_endio);
-		err = bio_add_page(bio, page, PAGE_SIZE, 0);
-		BUG_ON(err != PAGE_SIZE);
-
-		__submit_bio(bio, REQ_OP_READ,
-			REQ_META | (prio ? REQ_PRIO : 0));
-
+	page = read_cache_page_gfp(mapping, blkaddr,
+				   mapping_gfp_constraint(mapping, ~__GFP_FS));
+	/* should already be PageUptodate */
+	if (!IS_ERR(page))
 		lock_page(page);
-
-		/* the page has been truncated by others? */
-		if (unlikely(page->mapping != mapping)) {
-			unlock_page(page);
-			put_page(page);
-			goto repeat;
-		}
-
-		/* more likely a read error */
-		if (unlikely(!PageUptodate(page))) {
-			unlock_page(page);
-			put_page(page);
-
-			page = ERR_PTR(-EIO);
-		}
-	}
 	return page;
 }
 
 static int erofs_map_blocks_flatmode(struct inode *inode,
-	struct erofs_map_blocks *map,
-	int flags)
+				     struct erofs_map_blocks *map,
+				     int flags)
 {
 	int err = 0;
 	erofs_blk_t nblocks, lastblk;
 	u64 offset = map->m_la;
-	struct erofs_vnode *vi = EROFS_V(inode);
+	struct erofs_inode *vi = EROFS_I(inode);
+	bool tailendpacking = (vi->datalayout == EROFS_INODE_FLAT_INLINE);
 
 	trace_erofs_map_blocks_flatmode_enter(inode, map, flags);
 
 	nblocks = DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
-	lastblk = nblocks - is_inode_layout_inline(inode);
+	lastblk = nblocks - tailendpacking;
 
-	if (unlikely(offset >= inode->i_size)) {
+	if (offset >= inode->i_size) {
 		/* leave out-of-bound access unmapped */
 		map->m_flags = 0;
 		map->m_plen = 0;
@@ -114,7 +72,7 @@ static int erofs_map_blocks_flatmode(struct inode *inode,
 	if (offset < blknr_to_addr(lastblk)) {
 		map->m_pa = blknr_to_addr(vi->raw_blkaddr) + map->m_la;
 		map->m_plen = blknr_to_addr(lastblk) - offset;
-	} else if (is_inode_layout_inline(inode)) {
+	} else if (tailendpacking) {
 		/* 2 - inode inline B: inode, [xattrs], inline last blk... */
 		struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
 
@@ -122,17 +80,21 @@ static int erofs_map_blocks_flatmode(struct inode *inode,
 			vi->xattr_isize + erofs_blkoff(map->m_la);
 		map->m_plen = inode->i_size - offset;
 
-		/* inline data should locate in one meta block */
+		/* inline data should be located in one meta block */
 		if (erofs_blkoff(map->m_pa) + map->m_plen > PAGE_SIZE) {
+			erofs_err(inode->i_sb,
+				  "inline data cross block boundary @ nid %llu",
+				  vi->nid);
 			DBG_BUGON(1);
-			err = -EIO;
+			err = -EFSCORRUPTED;
 			goto err_out;
 		}
 
 		map->m_flags |= EROFS_MAP_META;
 	} else {
-		errln("internal error @ nid: %llu (size %llu), m_la 0x%llx",
-			vi->nid, inode->i_size, map->m_la);
+		erofs_err(inode->i_sb,
+			  "internal error @ nid: %llu (size %llu), m_la 0x%llx",
+			  vi->nid, inode->i_size, map->m_la);
 		DBG_BUGON(1);
 		err = -EIO;
 		goto err_out;
@@ -146,56 +108,30 @@ err_out:
 	return err;
 }
 
-#ifdef CONFIG_EROFS_FS_ZIP
-extern int z_erofs_map_blocks_iter(struct inode *,
-	struct erofs_map_blocks *, struct page **, int);
-#endif
-
-int erofs_map_blocks_iter(struct inode *inode,
-	struct erofs_map_blocks *map,
-	struct page **mpage_ret, int flags)
-{
-	/* by default, reading raw data never use erofs_map_blocks_iter */
-	if (unlikely(!is_inode_layout_compression(inode))) {
-		if (*mpage_ret != NULL)
-			put_page(*mpage_ret);
-		*mpage_ret = NULL;
-
-		return erofs_map_blocks(inode, map, flags);
-	}
-
-#ifdef CONFIG_EROFS_FS_ZIP
-	return z_erofs_map_blocks_iter(inode, map, mpage_ret, flags);
-#else
-	/* data compression is not available */
-	return -ENOTSUPP;
-#endif
-}
-
 int erofs_map_blocks(struct inode *inode,
-	struct erofs_map_blocks *map, int flags)
+		     struct erofs_map_blocks *map, int flags)
 {
-	if (unlikely(is_inode_layout_compression(inode))) {
-		struct page *mpage = NULL;
-		int err;
+	if (erofs_inode_is_data_compressed(EROFS_I(inode)->datalayout)) {
+		int err = z_erofs_map_blocks_iter(inode, map, flags);
 
-		err = erofs_map_blocks_iter(inode, map, &mpage, flags);
-		if (mpage != NULL)
-			put_page(mpage);
+		if (map->mpage) {
+			put_page(map->mpage);
+			map->mpage = NULL;
+		}
 		return err;
 	}
 	return erofs_map_blocks_flatmode(inode, map, flags);
 }
 
-static inline struct bio *erofs_read_raw_page(
-	struct bio *bio,
-	struct address_space *mapping,
-	struct page *page,
-	erofs_off_t *last_block,
-	unsigned nblocks,
-	bool ra)
+static inline struct bio *erofs_read_raw_page(struct bio *bio,
+					      struct address_space *mapping,
+					      struct page *page,
+					      erofs_off_t *last_block,
+					      unsigned int nblocks,
+					      bool ra)
 {
-	struct inode *inode = mapping->host;
+	struct inode *const inode = mapping->host;
+	struct super_block *const sb = inode->i_sb;
 	erofs_off_t current_block = (erofs_off_t)page->index;
 	int err;
 
@@ -206,34 +142,28 @@ static inline struct bio *erofs_read_raw_page(
 		goto has_updated;
 	}
 
-	if (cleancache_get_page(page) == 0) {
-		err = 0;
-		SetPageUptodate(page);
-		goto has_updated;
-	}
-
 	/* note that for readpage case, bio also equals to NULL */
-	if (bio != NULL &&
-		/* not continuous */
-		*last_block + 1 != current_block) {
+	if (bio &&
+	    /* not continuous */
+	    *last_block + 1 != current_block) {
 submit_bio_retry:
-		__submit_bio(bio, REQ_OP_READ, 0);
+		submit_bio(bio);
 		bio = NULL;
 	}
 
-	if (bio == NULL) {
+	if (!bio) {
 		struct erofs_map_blocks map = {
 			.m_la = blknr_to_addr(current_block),
 		};
 		erofs_blk_t blknr;
-		unsigned blkoff;
+		unsigned int blkoff;
 
 		err = erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW);
-		if (unlikely(err))
+		if (err)
 			goto err_out;
 
 		/* zero out the holed page */
-		if (unlikely(!(map.m_flags & EROFS_MAP_MAPPED))) {
+		if (!(map.m_flags & EROFS_MAP_MAPPED)) {
 			zero_user_segment(page, 0, PAGE_SIZE);
 			SetPageUptodate(page);
 
@@ -254,7 +184,7 @@ submit_bio_retry:
 
 			DBG_BUGON(map.m_plen > PAGE_SIZE);
 
-			ipage = erofs_get_meta_page(inode->i_sb, blknr, 0);
+			ipage = erofs_get_meta_page(inode->i_sb, blknr);
 
 			if (IS_ERR(ipage)) {
 				err = PTR_ERR(ipage);
@@ -287,7 +217,13 @@ submit_bio_retry:
 		if (nblocks > BIO_MAX_PAGES)
 			nblocks = BIO_MAX_PAGES;
 
-		bio = prepare_bio(inode->i_sb, blknr, nblocks, read_endio);
+		bio = bio_alloc(GFP_NOIO, nblocks);
+
+		bio->bi_end_io = erofs_readendio;
+		bio_set_dev(bio, sb->s_bdev);
+		bio->bi_iter.bi_sector = (sector_t)blknr <<
+			LOG_SECTORS_PER_BLOCK;
+		bio->bi_opf = REQ_OP_READ | (ra ? REQ_RAHEAD : 0);
 	}
 
 	err = bio_add_page(bio, page, PAGE_SIZE, 0);
@@ -298,7 +234,7 @@ submit_bio_retry:
 	*last_block = current_block;
 
 	/* shift in advance in case of it followed by too many gaps */
-	if (unlikely(bio->bi_vcnt >= bio->bi_max_vecs)) {
+	if (bio->bi_iter.bi_size >= bio->bi_max_vecs * PAGE_SIZE) {
 		/* err should reassign to 0 after submitting */
 		err = 0;
 		goto submit_bio_out;
@@ -316,11 +252,10 @@ has_updated:
 	unlock_page(page);
 
 	/* if updated manually, continuous pages has a gap */
-	if (bio != NULL)
+	if (bio)
 submit_bio_out:
-		__submit_bio(bio, REQ_OP_READ, 0);
-
-	return unlikely(err) ? ERR_PTR(err) : NULL;
+		submit_bio(bio);
+	return err ? ERR_PTR(err) : NULL;
 }
 
 /*
@@ -335,7 +270,7 @@ static int erofs_raw_access_readpage(struct file *file, struct page *page)
 	trace_erofs_readpage(page, true);
 
 	bio = erofs_read_raw_page(NULL, page->mapping,
-		page, &last_block, 1, false);
+				  page, &last_block, 1, false);
 
 	if (IS_ERR(bio))
 		return PTR_ERR(bio);
@@ -345,8 +280,9 @@ static int erofs_raw_access_readpage(struct file *file, struct page *page)
 }
 
 static int erofs_raw_access_readpages(struct file *filp,
-	struct address_space *mapping,
-	struct list_head *pages, unsigned nr_pages)
+				      struct address_space *mapping,
+				      struct list_head *pages,
+				      unsigned int nr_pages)
 {
 	erofs_off_t last_block;
 	struct bio *bio = NULL;
@@ -363,13 +299,13 @@ static int erofs_raw_access_readpages(struct file *filp,
 
 		if (!add_to_page_cache_lru(page, mapping, page->index, gfp)) {
 			bio = erofs_read_raw_page(bio, mapping, page,
-				&last_block, nr_pages, true);
+						  &last_block, nr_pages, true);
 
 			/* all the page errors are ignored when readahead */
 			if (IS_ERR(bio)) {
 				pr_err("%s, readahead error at page %lu of nid %llu\n",
-					__func__, page->index,
-					EROFS_V(mapping->host)->nid);
+				       __func__, page->index,
+				       EROFS_I(mapping->host)->nid);
 
 				bio = NULL;
 			}
@@ -381,8 +317,28 @@ static int erofs_raw_access_readpages(struct file *filp,
 	DBG_BUGON(!list_empty(pages));
 
 	/* the rare case (end in gaps) */
-	if (unlikely(bio != NULL))
-		__submit_bio(bio, REQ_OP_READ, 0);
+	if (bio)
+		submit_bio(bio);
+	return 0;
+}
+
+static sector_t erofs_bmap(struct address_space *mapping, sector_t block)
+{
+	struct inode *inode = mapping->host;
+	struct erofs_map_blocks map = {
+		.m_la = blknr_to_addr(block),
+	};
+
+	if (EROFS_I(inode)->datalayout == EROFS_INODE_FLAT_INLINE) {
+		erofs_blk_t blks = i_size_read(inode) >> LOG_BLOCK_SIZE;
+
+		if (block >> LOG_SECTORS_PER_BLOCK >= blks)
+			return 0;
+	}
+
+	if (!erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW))
+		return erofs_blknr(map.m_pa);
+
 	return 0;
 }
 
@@ -390,5 +346,5 @@ static int erofs_raw_access_readpages(struct file *filp,
 const struct address_space_operations erofs_raw_access_aops = {
 	.readpage = erofs_raw_access_readpage,
 	.readpages = erofs_raw_access_readpages,
+	.bmap = erofs_bmap,
 };
-
diff --git a/drivers/staging/erofs/decompressor.c b/drivers/staging/erofs/decompressor.c
new file mode 100644
index 000000000000..7822ab4a8262
--- /dev/null
+++ b/drivers/staging/erofs/decompressor.c
@@ -0,0 +1,344 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2019 HUAWEI, Inc.
+ *             https://www.huawei.com/
+ */
+#include "compress.h"
+#include <linux/module.h>
+#include <linux/lz4.h>
+
+#ifndef LZ4_DISTANCE_MAX	/* history window size */
+#define LZ4_DISTANCE_MAX 65535	/* set to maximum value by default */
+#endif
+
+#define LZ4_MAX_DISTANCE_PAGES	(DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) + 1)
+#ifndef LZ4_DECOMPRESS_INPLACE_MARGIN
+#define LZ4_DECOMPRESS_INPLACE_MARGIN(srcsize)  (((srcsize) >> 8) + 32)
+#endif
+
+struct z_erofs_decompressor {
+	/*
+	 * if destpages have sparsed pages, fill them with bounce pages.
+	 * it also check whether destpages indicate continuous physical memory.
+	 */
+	int (*prepare_destpages)(struct z_erofs_decompress_req *rq,
+				 struct list_head *pagepool);
+	int (*decompress)(struct z_erofs_decompress_req *rq, u8 *out);
+	char *name;
+};
+
+static int z_erofs_lz4_prepare_destpages(struct z_erofs_decompress_req *rq,
+					 struct list_head *pagepool)
+{
+	const unsigned int nr =
+		PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
+	struct page *availables[LZ4_MAX_DISTANCE_PAGES] = { NULL };
+	unsigned long bounced[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES,
+					   BITS_PER_LONG)] = { 0 };
+	void *kaddr = NULL;
+	unsigned int i, j, top;
+
+	top = 0;
+	for (i = j = 0; i < nr; ++i, ++j) {
+		struct page *const page = rq->out[i];
+		struct page *victim;
+
+		if (j >= LZ4_MAX_DISTANCE_PAGES)
+			j = 0;
+
+		/* 'valid' bounced can only be tested after a complete round */
+		if (test_bit(j, bounced)) {
+			DBG_BUGON(i < LZ4_MAX_DISTANCE_PAGES);
+			DBG_BUGON(top >= LZ4_MAX_DISTANCE_PAGES);
+			availables[top++] = rq->out[i - LZ4_MAX_DISTANCE_PAGES];
+		}
+
+		if (page) {
+			__clear_bit(j, bounced);
+			if (kaddr) {
+				if (kaddr + PAGE_SIZE == page_address(page))
+					kaddr += PAGE_SIZE;
+				else
+					kaddr = NULL;
+			} else if (!i) {
+				kaddr = page_address(page);
+			}
+			continue;
+		}
+		kaddr = NULL;
+		__set_bit(j, bounced);
+
+		if (top) {
+			victim = availables[--top];
+			get_page(victim);
+		} else {
+			victim = erofs_allocpage(pagepool, GFP_KERNEL);
+			if (!victim)
+				return -ENOMEM;
+			victim->mapping = Z_EROFS_MAPPING_STAGING;
+		}
+		rq->out[i] = victim;
+	}
+	return kaddr ? 1 : 0;
+}
+
+static void *generic_copy_inplace_data(struct z_erofs_decompress_req *rq,
+				       u8 *src, unsigned int pageofs_in)
+{
+	/*
+	 * if in-place decompression is ongoing, those decompressed
+	 * pages should be copied in order to avoid being overlapped.
+	 */
+	struct page **in = rq->in;
+	u8 *const tmp = erofs_get_pcpubuf(0);
+	u8 *tmpp = tmp;
+	unsigned int inlen = rq->inputsize - pageofs_in;
+	unsigned int count = min_t(uint, inlen, PAGE_SIZE - pageofs_in);
+
+	while (tmpp < tmp + inlen) {
+		if (!src)
+			src = kmap_atomic(*in);
+		memcpy(tmpp, src + pageofs_in, count);
+		kunmap_atomic(src);
+		src = NULL;
+		tmpp += count;
+		pageofs_in = 0;
+		count = PAGE_SIZE;
+		++in;
+	}
+	return tmp;
+}
+
+static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
+{
+	unsigned int inputmargin, inlen;
+	u8 *src;
+	bool copied, support_0padding;
+	int ret;
+
+	if (rq->inputsize > PAGE_SIZE)
+		return -EOPNOTSUPP;
+
+	src = kmap_atomic(*rq->in);
+	inputmargin = 0;
+	support_0padding = false;
+
+	/* decompression inplace is only safe when 0padding is enabled */
+	if (EROFS_SB(rq->sb)->feature_incompat &
+	    EROFS_FEATURE_INCOMPAT_LZ4_0PADDING) {
+		support_0padding = true;
+
+		while (!src[inputmargin & ~PAGE_MASK])
+			if (!(++inputmargin & ~PAGE_MASK))
+				break;
+
+		if (inputmargin >= rq->inputsize) {
+			kunmap_atomic(src);
+			return -EIO;
+		}
+	}
+
+	copied = false;
+	inlen = rq->inputsize - inputmargin;
+	if (rq->inplace_io) {
+		const uint oend = (rq->pageofs_out +
+				   rq->outputsize) & ~PAGE_MASK;
+		const uint nr = PAGE_ALIGN(rq->pageofs_out +
+					   rq->outputsize) >> PAGE_SHIFT;
+
+		if (rq->partial_decoding || !support_0padding ||
+		    rq->out[nr - 1] != rq->in[0] ||
+		    rq->inputsize - oend <
+		      LZ4_DECOMPRESS_INPLACE_MARGIN(inlen)) {
+			src = generic_copy_inplace_data(rq, src, inputmargin);
+			inputmargin = 0;
+			copied = true;
+		}
+	}
+
+	/* legacy format could compress extra data in a pcluster. */
+	if (rq->partial_decoding || !support_0padding)
+		ret = LZ4_decompress_safe_partial(src + inputmargin, out,
+						  inlen, rq->outputsize,
+						  rq->outputsize);
+	else
+		ret = LZ4_decompress_safe(src + inputmargin, out,
+					  inlen, rq->outputsize);
+
+	if (ret != rq->outputsize) {
+		erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
+			  ret, inlen, inputmargin, rq->outputsize);
+
+		WARN_ON(1);
+		print_hex_dump(KERN_DEBUG, "[ in]: ", DUMP_PREFIX_OFFSET,
+			       16, 1, src + inputmargin, inlen, true);
+		print_hex_dump(KERN_DEBUG, "[out]: ", DUMP_PREFIX_OFFSET,
+			       16, 1, out, rq->outputsize, true);
+
+		if (ret >= 0)
+			memset(out + ret, 0, rq->outputsize - ret);
+		ret = -EIO;
+	}
+
+	if (copied)
+		erofs_put_pcpubuf(src);
+	else
+		kunmap_atomic(src);
+	return ret;
+}
+
+static struct z_erofs_decompressor decompressors[] = {
+	[Z_EROFS_COMPRESSION_SHIFTED] = {
+		.name = "shifted"
+	},
+	[Z_EROFS_COMPRESSION_LZ4] = {
+		.prepare_destpages = z_erofs_lz4_prepare_destpages,
+		.decompress = z_erofs_lz4_decompress,
+		.name = "lz4"
+	},
+};
+
+static void copy_from_pcpubuf(struct page **out, const char *dst,
+			      unsigned short pageofs_out,
+			      unsigned int outputsize)
+{
+	const char *end = dst + outputsize;
+	const unsigned int righthalf = PAGE_SIZE - pageofs_out;
+	const char *cur = dst - pageofs_out;
+
+	while (cur < end) {
+		struct page *const page = *out++;
+
+		if (page) {
+			char *buf = kmap_atomic(page);
+
+			if (cur >= dst) {
+				memcpy(buf, cur, min_t(uint, PAGE_SIZE,
+						       end - cur));
+			} else {
+				memcpy(buf + pageofs_out, cur + pageofs_out,
+				       min_t(uint, righthalf, end - cur));
+			}
+			kunmap_atomic(buf);
+		}
+		cur += PAGE_SIZE;
+	}
+}
+
+static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq,
+				      struct list_head *pagepool)
+{
+	const unsigned int nrpages_out =
+		PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
+	const struct z_erofs_decompressor *alg = decompressors + rq->alg;
+	unsigned int dst_maptype;
+	void *dst;
+	int ret, i;
+
+	if (nrpages_out == 1 && !rq->inplace_io) {
+		DBG_BUGON(!*rq->out);
+		dst = kmap_atomic(*rq->out);
+		dst_maptype = 0;
+		goto dstmap_out;
+	}
+
+	/*
+	 * For the case of small output size (especially much less
+	 * than PAGE_SIZE), memcpy the decompressed data rather than
+	 * compressed data is preferred.
+	 */
+	if (rq->outputsize <= PAGE_SIZE * 7 / 8) {
+		dst = erofs_get_pcpubuf(0);
+		if (IS_ERR(dst))
+			return PTR_ERR(dst);
+
+		rq->inplace_io = false;
+		ret = alg->decompress(rq, dst);
+		if (!ret)
+			copy_from_pcpubuf(rq->out, dst, rq->pageofs_out,
+					  rq->outputsize);
+
+		erofs_put_pcpubuf(dst);
+		return ret;
+	}
+
+	ret = alg->prepare_destpages(rq, pagepool);
+	if (ret < 0) {
+		return ret;
+	} else if (ret) {
+		dst = page_address(*rq->out);
+		dst_maptype = 1;
+		goto dstmap_out;
+	}
+
+	i = 0;
+	while (1) {
+		dst = vm_map_ram(rq->out, nrpages_out, -1, PAGE_KERNEL);
+
+		/* retry two more times (totally 3 times) */
+		if (dst || ++i >= 3)
+			break;
+		vm_unmap_aliases();
+	}
+
+	if (!dst)
+		return -ENOMEM;
+
+	dst_maptype = 2;
+
+dstmap_out:
+	ret = alg->decompress(rq, dst + rq->pageofs_out);
+
+	if (!dst_maptype)
+		kunmap_atomic(dst);
+	else if (dst_maptype == 2)
+		vm_unmap_ram(dst, nrpages_out);
+	return ret;
+}
+
+static int z_erofs_shifted_transform(const struct z_erofs_decompress_req *rq,
+				     struct list_head *pagepool)
+{
+	const unsigned int nrpages_out =
+		PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
+	const unsigned int righthalf = PAGE_SIZE - rq->pageofs_out;
+	unsigned char *src, *dst;
+
+	if (nrpages_out > 2) {
+		DBG_BUGON(1);
+		return -EIO;
+	}
+
+	if (rq->out[0] == *rq->in) {
+		DBG_BUGON(nrpages_out != 1);
+		return 0;
+	}
+
+	src = kmap_atomic(*rq->in);
+	if (rq->out[0]) {
+		dst = kmap_atomic(rq->out[0]);
+		memcpy(dst + rq->pageofs_out, src, righthalf);
+		kunmap_atomic(dst);
+	}
+
+	if (nrpages_out == 2) {
+		DBG_BUGON(!rq->out[1]);
+		if (rq->out[1] == *rq->in) {
+			memmove(src, src + righthalf, rq->pageofs_out);
+		} else {
+			dst = kmap_atomic(rq->out[1]);
+			memcpy(dst, src + righthalf, rq->pageofs_out);
+			kunmap_atomic(dst);
+		}
+	}
+	kunmap_atomic(src);
+	return 0;
+}
+
+int z_erofs_decompress(struct z_erofs_decompress_req *rq,
+		       struct list_head *pagepool)
+{
+	if (rq->alg == Z_EROFS_COMPRESSION_SHIFTED)
+		return z_erofs_shifted_transform(rq, pagepool);
+	return z_erofs_decompress_generic(rq, pagepool);
+}
diff --git a/drivers/staging/erofs/dir.c b/drivers/staging/erofs/dir.c
index fe6683effd05..722b653c7a77 100644
--- a/drivers/staging/erofs/dir.c
+++ b/drivers/staging/erofs/dir.c
@@ -1,14 +1,7 @@
-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
- * linux/drivers/staging/erofs/dir.c
- *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
+ *             https://www.huawei.com/
  */
 #include "internal.h"
 
@@ -33,19 +26,18 @@ static void debug_one_dentry(unsigned char d_type, const char *de_name,
 	memcpy(dbg_namebuf, de_name, de_namelen);
 	dbg_namebuf[de_namelen] = '\0';
 
-	debugln("found dirent %s de_len %u d_type %d", dbg_namebuf,
-		de_namelen, d_type);
+	erofs_dbg("found dirent %s de_len %u d_type %d", dbg_namebuf,
+		  de_namelen, d_type);
 #endif
 }
 
-static int erofs_fill_dentries(struct dir_context *ctx,
-	void *dentry_blk, unsigned *ofs,
-	unsigned nameoff, unsigned maxsize)
+static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx,
+			       void *dentry_blk, unsigned int *ofs,
+			       unsigned int nameoff, unsigned int maxsize)
 {
-	struct erofs_dirent *de = dentry_blk;
+	struct erofs_dirent *de = dentry_blk + *ofs;
 	const struct erofs_dirent *end = dentry_blk + nameoff;
 
-	de = dentry_blk + *ofs;
 	while (de < end) {
 		const char *de_name;
 		unsigned int de_namelen;
@@ -66,16 +58,18 @@ static int erofs_fill_dentries(struct dir_context *ctx,
 			de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;
 
 		/* a corrupted entry is found */
-		if (unlikely(nameoff + de_namelen > maxsize ||
-			     de_namelen > EROFS_NAME_LEN)) {
+		if (nameoff + de_namelen > maxsize ||
+		    de_namelen > EROFS_NAME_LEN) {
+			erofs_err(dir->i_sb, "bogus dirent @ nid %llu",
+				  EROFS_I(dir)->nid);
 			DBG_BUGON(1);
-			return -EIO;
+			return -EFSCORRUPTED;
 		}
 
 		debug_one_dentry(d_type, de_name, de_namelen);
 		if (!dir_emit(ctx, de_name, de_namelen,
-					le64_to_cpu(de->nid), d_type))
-			/* stoped by some reason */
+			      le64_to_cpu(de->nid), d_type))
+			/* stopped by some reason */
 			return 1;
 		++de;
 		*ofs += sizeof(struct erofs_dirent);
@@ -89,62 +83,63 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
 	struct inode *dir = file_inode(f);
 	struct address_space *mapping = dir->i_mapping;
 	const size_t dirsize = i_size_read(dir);
-	unsigned i = ctx->pos / EROFS_BLKSIZ;
-	unsigned ofs = ctx->pos % EROFS_BLKSIZ;
+	unsigned int i = ctx->pos / EROFS_BLKSIZ;
+	unsigned int ofs = ctx->pos % EROFS_BLKSIZ;
 	int err = 0;
 	bool initial = true;
 
 	while (ctx->pos < dirsize) {
 		struct page *dentry_page;
 		struct erofs_dirent *de;
-		unsigned nameoff, maxsize;
+		unsigned int nameoff, maxsize;
 
 		dentry_page = read_mapping_page(mapping, i, NULL);
 		if (dentry_page == ERR_PTR(-ENOMEM)) {
 			err = -ENOMEM;
 			break;
 		} else if (IS_ERR(dentry_page)) {
-			errln("fail to readdir of logical block %u of nid %llu",
-			      i, EROFS_V(dir)->nid);
-			err = PTR_ERR(dentry_page);
+			erofs_err(dir->i_sb,
+				  "fail to readdir of logical block %u of nid %llu",
+				  i, EROFS_I(dir)->nid);
+			err = -EFSCORRUPTED;
 			break;
 		}
 
-		lock_page(dentry_page);
 		de = (struct erofs_dirent *)kmap(dentry_page);
 
 		nameoff = le16_to_cpu(de->nameoff);
 
-		if (unlikely(nameoff < sizeof(struct erofs_dirent) ||
-			nameoff >= PAGE_SIZE)) {
-			errln("%s, invalid de[0].nameoff %u",
-				__func__, nameoff);
-
-			err = -EIO;
+		if (nameoff < sizeof(struct erofs_dirent) ||
+		    nameoff >= PAGE_SIZE) {
+			erofs_err(dir->i_sb,
+				  "invalid de[0].nameoff %u @ nid %llu",
+				  nameoff, EROFS_I(dir)->nid);
+			err = -EFSCORRUPTED;
 			goto skip_this;
 		}
 
-		maxsize = min_t(unsigned, dirsize - ctx->pos + ofs, PAGE_SIZE);
+		maxsize = min_t(unsigned int,
+				dirsize - ctx->pos + ofs, PAGE_SIZE);
 
 		/* search dirents at the arbitrary position */
-		if (unlikely(initial)) {
+		if (initial) {
 			initial = false;
 
 			ofs = roundup(ofs, sizeof(struct erofs_dirent));
-			if (unlikely(ofs >= nameoff))
+			if (ofs >= nameoff)
 				goto skip_this;
 		}
 
-		err = erofs_fill_dentries(ctx, de, &ofs, nameoff, maxsize);
+		err = erofs_fill_dentries(dir, ctx, de, &ofs,
+					  nameoff, maxsize);
 skip_this:
 		kunmap(dentry_page);
 
-		unlock_page(dentry_page);
 		put_page(dentry_page);
 
 		ctx->pos = blknr_to_addr(i) + ofs;
 
-		if (unlikely(err))
+		if (err)
 			break;
 		++i;
 		ofs = 0;
@@ -155,6 +150,5 @@ skip_this:
 const struct file_operations erofs_dir_fops = {
 	.llseek		= generic_file_llseek,
 	.read		= generic_read_dir,
-	.iterate	= erofs_readdir,
+	.iterate_shared	= erofs_readdir,
 };
-
diff --git a/drivers/staging/erofs/erofs_fs.h b/drivers/staging/erofs/erofs_fs.h
index d8838ce66941..011c3e281f7f 100644
--- a/drivers/staging/erofs/erofs_fs.h
+++ b/drivers/staging/erofs/erofs_fs.h
@@ -1,115 +1,121 @@
-/* SPDX-License-Identifier: GPL-2.0 OR Apache-2.0
- *
- * linux/drivers/staging/erofs/erofs_fs.h
+/* SPDX-License-Identifier: GPL-2.0-only OR Apache-2.0 */
+/*
+ * EROFS (Enhanced ROM File System) on-disk format definition
  *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is dual-licensed; you may select either the GNU General Public
- * License version 2 or Apache License, Version 2.0. See the file COPYING
- * in the main directory of the Linux distribution for more details.
+ *             https://www.huawei.com/
  */
 #ifndef __EROFS_FS_H
 #define __EROFS_FS_H
 
-/* Enhanced(Extended) ROM File System */
-#define EROFS_SUPER_MAGIC_V1    0xE0F5E1E2
+#define EROFS_SUPER_MAGIC_V1	0xE0F5E1E2
 #define EROFS_SUPER_OFFSET      1024
 
+#define EROFS_FEATURE_COMPAT_SB_CHKSUM          0x00000001
+
 /*
- * Any bits that aren't in EROFS_ALL_REQUIREMENTS should be
- * incompatible with this kernel version.
+ * Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should
+ * be incompatible with this kernel version.
  */
-#define EROFS_ALL_REQUIREMENTS  0
+#define EROFS_FEATURE_INCOMPAT_LZ4_0PADDING	0x00000001
+#define EROFS_ALL_FEATURE_INCOMPAT		EROFS_FEATURE_INCOMPAT_LZ4_0PADDING
 
+/* 128-byte erofs on-disk super block */
 struct erofs_super_block {
-/*  0 */__le32 magic;           /* in the little endian */
-/*  4 */__le32 checksum;        /* crc32c(super_block) */
-/*  8 */__le32 features;        /* (aka. feature_compat) */
-/* 12 */__u8 blkszbits;         /* support block_size == PAGE_SIZE only */
-/* 13 */__u8 reserved;
-
-/* 14 */__le16 root_nid;
-/* 16 */__le64 inos;            /* total valid ino # (== f_files - f_favail) */
-
-/* 24 */__le64 build_time;      /* inode v1 time derivation */
-/* 32 */__le32 build_time_nsec;
-/* 36 */__le32 blocks;          /* used for statfs */
-/* 40 */__le32 meta_blkaddr;
-/* 44 */__le32 xattr_blkaddr;
-/* 48 */__u8 uuid[16];          /* 128-bit uuid for volume */
-/* 64 */__u8 volume_name[16];   /* volume name */
-/* 80 */__le32 requirements;    /* (aka. feature_incompat) */
-
-/* 84 */__u8 reserved2[44];
-} __packed;                     /* 128 bytes */
-
-#define __EROFS_BIT(_prefix, _cur, _pre)	enum {	\
-	_prefix ## _cur ## _BIT = _prefix ## _pre ## _BIT + \
-		_prefix ## _pre ## _BITS }
+	__le32 magic;           /* file system magic number */
+	__le32 checksum;        /* crc32c(super_block) */
+	__le32 feature_compat;
+	__u8 blkszbits;         /* support block_size == PAGE_SIZE only */
+	__u8 reserved;
+
+	__le16 root_nid;	/* nid of root directory */
+	__le64 inos;            /* total valid ino # (== f_files - f_favail) */
+
+	__le64 build_time;      /* inode v1 time derivation */
+	__le32 build_time_nsec;	/* inode v1 time derivation in nano scale */
+	__le32 blocks;          /* used for statfs */
+	__le32 meta_blkaddr;	/* start block address of metadata area */
+	__le32 xattr_blkaddr;	/* start block address of shared xattr area */
+	__u8 uuid[16];          /* 128-bit uuid for volume */
+	__u8 volume_name[16];   /* volume name */
+	__le32 feature_incompat;
+	__u8 reserved2[44];
+};
 
 /*
- * erofs inode data mapping:
+ * erofs inode datalayout (i_format in on-disk inode):
  * 0 - inode plain without inline data A:
  * inode, [xattrs], ... | ... | no-holed data
- * 1 - inode VLE compression B:
+ * 1 - inode VLE compression B (legacy):
  * inode, [xattrs], extents ... | ...
  * 2 - inode plain with inline data C:
  * inode, [xattrs], last_inline_data, ... | ... | no-holed data
- * 3~7 - reserved
+ * 3 - inode compression D:
+ * inode, [xattrs], map_header, extents ... | ...
+ * 4~7 - reserved
  */
 enum {
-	EROFS_INODE_LAYOUT_PLAIN,
-	EROFS_INODE_LAYOUT_COMPRESSION,
-	EROFS_INODE_LAYOUT_INLINE,
-	EROFS_INODE_LAYOUT_MAX
+	EROFS_INODE_FLAT_PLAIN			= 0,
+	EROFS_INODE_FLAT_COMPRESSION_LEGACY	= 1,
+	EROFS_INODE_FLAT_INLINE			= 2,
+	EROFS_INODE_FLAT_COMPRESSION		= 3,
+	EROFS_INODE_DATALAYOUT_MAX
 };
+
+static inline bool erofs_inode_is_data_compressed(unsigned int datamode)
+{
+	return datamode == EROFS_INODE_FLAT_COMPRESSION ||
+		datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY;
+}
+
+/* bit definitions of inode i_advise */
 #define EROFS_I_VERSION_BITS            1
-#define EROFS_I_DATA_MAPPING_BITS       3
+#define EROFS_I_DATALAYOUT_BITS         3
 
 #define EROFS_I_VERSION_BIT             0
-__EROFS_BIT(EROFS_I_, DATA_MAPPING, VERSION);
+#define EROFS_I_DATALAYOUT_BIT          1
 
 #define EROFS_I_ALL	\
-	((1 << (EROFS_I_DATA_MAPPING_BIT + EROFS_I_DATA_MAPPING_BITS)) - 1)
+	((1 << (EROFS_I_DATALAYOUT_BIT + EROFS_I_DATALAYOUT_BITS)) - 1)
 
-struct erofs_inode_v1 {
-/*  0 */__le16 i_advise;
+/* 32-byte reduced form of an ondisk inode */
+struct erofs_inode_compact {
+	__le16 i_format;	/* inode format hints */
 
 /* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
-/*  2 */__le16 i_xattr_icount;
-/*  4 */__le16 i_mode;
-/*  6 */__le16 i_nlink;
-/*  8 */__le32 i_size;
-/* 12 */__le32 i_reserved;
-/* 16 */union {
+	__le16 i_xattr_icount;
+	__le16 i_mode;
+	__le16 i_nlink;
+	__le32 i_size;
+	__le32 i_reserved;
+	union {
 		/* file total compressed blocks for data mapping 1 */
 		__le32 compressed_blocks;
 		__le32 raw_blkaddr;
 
 		/* for device files, used to indicate old/new device # */
 		__le32 rdev;
-	} i_u __packed;
-/* 20 */__le32 i_ino;           /* only used for 32-bit stat compatibility */
-/* 24 */__le16 i_uid;
-/* 26 */__le16 i_gid;
-/* 28 */__le32 i_checksum;
-} __packed;
+	} i_u;
+	__le32 i_ino;           /* only used for 32-bit stat compatibility */
+	__le16 i_uid;
+	__le16 i_gid;
+	__le32 i_reserved2;
+};
 
 /* 32 bytes on-disk inode */
-#define EROFS_INODE_LAYOUT_V1   0
+#define EROFS_INODE_LAYOUT_COMPACT	0
 /* 64 bytes on-disk inode */
-#define EROFS_INODE_LAYOUT_V2   1
+#define EROFS_INODE_LAYOUT_EXTENDED	1
 
-struct erofs_inode_v2 {
-	__le16 i_advise;
+/* 64-byte complete form of an ondisk inode */
+struct erofs_inode_extended {
+	__le16 i_format;	/* inode format hints */
 
-	/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
+/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */
 	__le16 i_xattr_icount;
 	__le16 i_mode;
-	__le16 i_reserved;      /* 8 bytes */
-	__le64 i_size;          /* 16 bytes */
+	__le16 i_reserved;
+	__le64 i_size;
 	union {
 		/* file total compressed blocks for data mapping 1 */
 		__le32 compressed_blocks;
@@ -117,19 +123,18 @@ struct erofs_inode_v2 {
 
 		/* for device files, used to indicate old/new device # */
 		__le32 rdev;
-	} i_u __packed;
+	} i_u;
 
 	/* only used for 32-bit stat compatibility */
-	__le32 i_ino;           /* 24 bytes */
+	__le32 i_ino;
 
 	__le32 i_uid;
 	__le32 i_gid;
-	__le64 i_ctime;         /* 32 bytes */
+	__le64 i_ctime;
 	__le32 i_ctime_nsec;
 	__le32 i_nlink;
-	__u8   i_reserved2[12];
-	__le32 i_checksum;      /* 64 bytes */
-} __packed;
+	__u8   i_reserved2[16];
+};
 
 #define EROFS_MAX_SHARED_XATTRS         (128)
 /* h_shared_count between 129 ... 255 are special # */
@@ -147,11 +152,11 @@ struct erofs_inode_v2 {
  * for read-only fs, no need to introduce h_refcount
  */
 struct erofs_xattr_ibody_header {
-	__le32 h_checksum;
+	__le32 h_reserved;
 	__u8   h_shared_count;
-	__u8   h_reserved[7];
+	__u8   h_reserved2[7];
 	__le32 h_shared_xattrs[0];      /* shared xattr id array */
-} __packed;
+};
 
 /* Name indexes */
 #define EROFS_XATTR_INDEX_USER              1
@@ -168,27 +173,61 @@ struct erofs_xattr_entry {
 	__le16 e_value_size;    /* size of attribute value */
 	/* followed by e_name and e_value */
 	char   e_name[0];       /* attribute name */
-} __packed;
+};
 
-#define ondisk_xattr_ibody_size(count)	({\
-	u32 __count = le16_to_cpu(count); \
-	((__count) == 0) ? 0 : \
-	sizeof(struct erofs_xattr_ibody_header) + \
-		sizeof(__u32) * ((__count) - 1); })
+static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount)
+{
+	if (!i_xattr_icount)
+		return 0;
+
+	return sizeof(struct erofs_xattr_ibody_header) +
+		sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1);
+}
 
 #define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry))
-#define EROFS_XATTR_ENTRY_SIZE(entry) EROFS_XATTR_ALIGN( \
-	sizeof(struct erofs_xattr_entry) + \
-	(entry)->e_name_len + le16_to_cpu((entry)->e_value_size))
-
-/* have to be aligned with 8 bytes on disk */
-struct erofs_extent_header {
-	__le32 eh_checksum;
-	__le32 eh_reserved[3];
-} __packed;
+
+static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e)
+{
+	return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) +
+				 e->e_name_len + le16_to_cpu(e->e_value_size));
+}
+
+/* available compression algorithm types (for h_algorithmtype) */
+enum {
+	Z_EROFS_COMPRESSION_LZ4	= 0,
+	Z_EROFS_COMPRESSION_MAX
+};
 
 /*
- * Z_EROFS Variable-sized Logical Extent cluster type:
+ * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
+ *  e.g. for 4k logical cluster size,      4B        if compacted 2B is off;
+ *                                  (4B) + 2B + (4B) if compacted 2B is on.
+ */
+#define Z_EROFS_ADVISE_COMPACTED_2B_BIT         0
+
+#define Z_EROFS_ADVISE_COMPACTED_2B     (1 << Z_EROFS_ADVISE_COMPACTED_2B_BIT)
+
+struct z_erofs_map_header {
+	__le32	h_reserved1;
+	__le16	h_advise;
+	/*
+	 * bit 0-3 : algorithm type of head 1 (logical cluster type 01);
+	 * bit 4-7 : algorithm type of head 2 (logical cluster type 11).
+	 */
+	__u8	h_algorithmtype;
+	/*
+	 * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096;
+	 * bit 3-4 : (physical - logical) cluster bits of head 1:
+	 *       For example, if logical clustersize = 4096, 1 for 8192.
+	 * bit 5-7 : (physical - logical) cluster bits of head 2.
+	 */
+	__u8	h_clusterbits;
+};
+
+#define Z_EROFS_VLE_LEGACY_HEADER_PADDING       8
+
+/*
+ * Fixed-sized output compression ondisk Logical Extent cluster type:
  *    0 - literal (uncompressed) cluster
  *    1 - compressed cluster (for the head logical cluster)
  *    2 - compressed cluster (for the other logical clusters)
@@ -212,6 +251,14 @@ struct erofs_extent_header {
  *        di_u.delta[1] = distance to its corresponding tail cluster
  *                (di_advise could be 0, 1 or 2)
  */
+enum {
+	Z_EROFS_VLE_CLUSTER_TYPE_PLAIN		= 0,
+	Z_EROFS_VLE_CLUSTER_TYPE_HEAD		= 1,
+	Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD	= 2,
+	Z_EROFS_VLE_CLUSTER_TYPE_RESERVED	= 3,
+	Z_EROFS_VLE_CLUSTER_TYPE_MAX
+};
+
 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS        2
 #define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT         0
 
@@ -230,18 +277,19 @@ struct z_erofs_vle_decompressed_index {
 		 * [1] - pointing to the tail cluster
 		 */
 		__le16 delta[2];
-	} di_u __packed;		/* 8 bytes */
-} __packed;
+	} di_u;
+};
 
-#define Z_EROFS_VLE_EXTENT_ALIGN(size) round_up(size, \
-	sizeof(struct z_erofs_vle_decompressed_index))
+#define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \
+	(round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \
+	 sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING)
 
 /* dirent sorts in alphabet order, thus we can do binary search */
 struct erofs_dirent {
-	__le64 nid;     /*  0, node number */
-	__le16 nameoff; /*  8, start offset of file name */
-	__u8 file_type; /* 10, file type */
-	__u8 reserved;  /* 11, reserved */
+	__le64 nid;     /* node number */
+	__le16 nameoff; /* start offset of file name */
+	__u8 file_type; /* file type */
+	__u8 reserved;  /* reserved */
 } __packed;
 
 /* file types used in inode_info->flags */
@@ -263,14 +311,16 @@ enum {
 static inline void erofs_check_ondisk_layout_definitions(void)
 {
 	BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128);
-	BUILD_BUG_ON(sizeof(struct erofs_inode_v1) != 32);
-	BUILD_BUG_ON(sizeof(struct erofs_inode_v2) != 64);
+	BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32);
+	BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64);
 	BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12);
 	BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4);
-	BUILD_BUG_ON(sizeof(struct erofs_extent_header) != 16);
+	BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8);
 	BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8);
 	BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12);
+
+	BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) <
+		     Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1);
 }
 
 #endif
-
diff --git a/drivers/staging/erofs/inode.c b/drivers/staging/erofs/inode.c
index 02398c7eb4a4..5f9c6fb79ac0 100644
--- a/drivers/staging/erofs/inode.c
+++ b/drivers/staging/erofs/inode.c
@@ -1,14 +1,7 @@
-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
- * linux/drivers/staging/erofs/inode.c
- *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
+ *             https://www.huawei.com/
  */
 #include "xattr.h"
 
@@ -19,56 +12,59 @@
  * the inode payload page if it's an extended inode) in order to fill
  * inline data if possible.
  */
-static struct page *read_inode(struct inode *inode, unsigned int *ofs)
+static struct page *erofs_read_inode(struct inode *inode,
+				     unsigned int *ofs)
 {
 	struct super_block *sb = inode->i_sb;
 	struct erofs_sb_info *sbi = EROFS_SB(sb);
-	struct erofs_vnode *vi = EROFS_V(inode);
+	struct erofs_inode *vi = EROFS_I(inode);
 	const erofs_off_t inode_loc = iloc(sbi, vi->nid);
-	erofs_blk_t blkaddr;
+
+	erofs_blk_t blkaddr, nblks = 0;
 	struct page *page;
-	struct erofs_inode_v1 *v1;
-	struct erofs_inode_v2 *v2, *copied = NULL;
+	struct erofs_inode_compact *dic;
+	struct erofs_inode_extended *die, *copied = NULL;
 	unsigned int ifmt;
 	int err;
 
 	blkaddr = erofs_blknr(inode_loc);
 	*ofs = erofs_blkoff(inode_loc);
 
-	debugln("%s, reading inode nid %llu at %u of blkaddr %u",
-		__func__, vi->nid, *ofs, blkaddr);
+	erofs_dbg("%s, reading inode nid %llu at %u of blkaddr %u",
+		  __func__, vi->nid, *ofs, blkaddr);
 
-	page = erofs_get_meta_page(sb, blkaddr, false);
+	page = erofs_get_meta_page(sb, blkaddr);
 	if (IS_ERR(page)) {
-		errln("failed to get inode (nid: %llu) page, err %ld",
-		      vi->nid, PTR_ERR(page));
+		erofs_err(sb, "failed to get inode (nid: %llu) page, err %ld",
+			  vi->nid, PTR_ERR(page));
 		return page;
 	}
 
-	v1 = page_address(page) + *ofs;
-	ifmt = le16_to_cpu(v1->i_advise);
+	dic = page_address(page) + *ofs;
+	ifmt = le16_to_cpu(dic->i_format);
 
 	if (ifmt & ~EROFS_I_ALL) {
-		errln("unsupported i_format %u of nid %llu", ifmt, vi->nid);
+		erofs_err(inode->i_sb, "unsupported i_format %u of nid %llu",
+			  ifmt, vi->nid);
 		err = -EOPNOTSUPP;
 		goto err_out;
 	}
 
-	vi->data_mapping_mode = __inode_data_mapping(ifmt);
-	if (unlikely(vi->data_mapping_mode >= EROFS_INODE_LAYOUT_MAX)) {
-		errln("unknown data mapping mode %u of nid %llu",
-			vi->data_mapping_mode, vi->nid);
+	vi->datalayout = erofs_inode_datalayout(ifmt);
+	if (vi->datalayout >= EROFS_INODE_DATALAYOUT_MAX) {
+		erofs_err(inode->i_sb, "unsupported datalayout %u of nid %llu",
+			  vi->datalayout, vi->nid);
 		err = -EOPNOTSUPP;
 		goto err_out;
 	}
 
-	switch (__inode_version(ifmt)) {
-	case EROFS_INODE_LAYOUT_V2:
-		vi->inode_isize = sizeof(struct erofs_inode_v2);
+	switch (erofs_inode_version(ifmt)) {
+	case EROFS_INODE_LAYOUT_EXTENDED:
+		vi->inode_isize = sizeof(struct erofs_inode_extended);
 		/* check if the inode acrosses page boundary */
 		if (*ofs + vi->inode_isize <= PAGE_SIZE) {
 			*ofs += vi->inode_isize;
-			v2 = (struct erofs_inode_v2 *)v1;
+			die = (struct erofs_inode_extended *)dic;
 		} else {
 			const unsigned int gotten = PAGE_SIZE - *ofs;
 
@@ -77,78 +73,98 @@ static struct page *read_inode(struct inode *inode, unsigned int *ofs)
 				err = -ENOMEM;
 				goto err_out;
 			}
-			memcpy(copied, v1, gotten);
+			memcpy(copied, dic, gotten);
 			unlock_page(page);
 			put_page(page);
 
-			page = erofs_get_meta_page(sb, blkaddr + 1, false);
+			page = erofs_get_meta_page(sb, blkaddr + 1);
 			if (IS_ERR(page)) {
-				errln("failed to get inode payload page (nid: %llu), err %ld",
-				      vi->nid, PTR_ERR(page));
+				erofs_err(sb, "failed to get inode payload page (nid: %llu), err %ld",
+					  vi->nid, PTR_ERR(page));
 				kfree(copied);
 				return page;
 			}
 			*ofs = vi->inode_isize - gotten;
 			memcpy((u8 *)copied + gotten, page_address(page), *ofs);
-			v2 = copied;
+			die = copied;
 		}
-		vi->xattr_isize = ondisk_xattr_ibody_size(v2->i_xattr_icount);
-
-		inode->i_mode = le16_to_cpu(v2->i_mode);
-		if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
-						S_ISLNK(inode->i_mode)) {
-			vi->raw_blkaddr = le32_to_cpu(v2->i_u.raw_blkaddr);
-		} else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
+		vi->xattr_isize = erofs_xattr_ibody_size(die->i_xattr_icount);
+
+		inode->i_mode = le16_to_cpu(die->i_mode);
+		switch (inode->i_mode & S_IFMT) {
+		case S_IFREG:
+		case S_IFDIR:
+		case S_IFLNK:
+			vi->raw_blkaddr = le32_to_cpu(die->i_u.raw_blkaddr);
+			break;
+		case S_IFCHR:
+		case S_IFBLK:
 			inode->i_rdev =
-				new_decode_dev(le32_to_cpu(v2->i_u.rdev));
-		} else if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
+				new_decode_dev(le32_to_cpu(die->i_u.rdev));
+			break;
+		case S_IFIFO:
+		case S_IFSOCK:
 			inode->i_rdev = 0;
-		} else {
+			break;
+		default:
 			goto bogusimode;
 		}
-
-		i_uid_write(inode, le32_to_cpu(v2->i_uid));
-		i_gid_write(inode, le32_to_cpu(v2->i_gid));
-		set_nlink(inode, le32_to_cpu(v2->i_nlink));
+		i_uid_write(inode, le32_to_cpu(die->i_uid));
+		i_gid_write(inode, le32_to_cpu(die->i_gid));
+		set_nlink(inode, le32_to_cpu(die->i_nlink));
 
 		/* extended inode has its own timestamp */
-		inode->i_ctime.tv_sec = le64_to_cpu(v2->i_ctime);
-		inode->i_ctime.tv_nsec = le32_to_cpu(v2->i_ctime_nsec);
+		inode->i_ctime.tv_sec = le64_to_cpu(die->i_ctime);
+		inode->i_ctime.tv_nsec = le32_to_cpu(die->i_ctime_nsec);
+
+		inode->i_size = le64_to_cpu(die->i_size);
+
+		/* total blocks for compressed files */
+		if (erofs_inode_is_data_compressed(vi->datalayout))
+			nblks = le32_to_cpu(die->i_u.compressed_blocks);
 
-		inode->i_size = le64_to_cpu(v2->i_size);
 		kfree(copied);
 		break;
-	case EROFS_INODE_LAYOUT_V1:
-		vi->inode_isize = sizeof(struct erofs_inode_v1);
+	case EROFS_INODE_LAYOUT_COMPACT:
+		vi->inode_isize = sizeof(struct erofs_inode_compact);
 		*ofs += vi->inode_isize;
-		vi->xattr_isize = ondisk_xattr_ibody_size(v1->i_xattr_icount);
-
-		inode->i_mode = le16_to_cpu(v1->i_mode);
-		if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
-						S_ISLNK(inode->i_mode)) {
-			vi->raw_blkaddr = le32_to_cpu(v1->i_u.raw_blkaddr);
-		} else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
+		vi->xattr_isize = erofs_xattr_ibody_size(dic->i_xattr_icount);
+
+		inode->i_mode = le16_to_cpu(dic->i_mode);
+		switch (inode->i_mode & S_IFMT) {
+		case S_IFREG:
+		case S_IFDIR:
+		case S_IFLNK:
+			vi->raw_blkaddr = le32_to_cpu(dic->i_u.raw_blkaddr);
+			break;
+		case S_IFCHR:
+		case S_IFBLK:
 			inode->i_rdev =
-				new_decode_dev(le32_to_cpu(v1->i_u.rdev));
-		} else if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
+				new_decode_dev(le32_to_cpu(dic->i_u.rdev));
+			break;
+		case S_IFIFO:
+		case S_IFSOCK:
 			inode->i_rdev = 0;
-		} else {
+			break;
+		default:
 			goto bogusimode;
 		}
-
-		i_uid_write(inode, le16_to_cpu(v1->i_uid));
-		i_gid_write(inode, le16_to_cpu(v1->i_gid));
-		set_nlink(inode, le16_to_cpu(v1->i_nlink));
+		i_uid_write(inode, le16_to_cpu(dic->i_uid));
+		i_gid_write(inode, le16_to_cpu(dic->i_gid));
+		set_nlink(inode, le16_to_cpu(dic->i_nlink));
 
 		/* use build time for compact inodes */
 		inode->i_ctime.tv_sec = sbi->build_time;
 		inode->i_ctime.tv_nsec = sbi->build_time_nsec;
 
-		inode->i_size = le32_to_cpu(v1->i_size);
+		inode->i_size = le32_to_cpu(dic->i_size);
+		if (erofs_inode_is_data_compressed(vi->datalayout))
+			nblks = le32_to_cpu(dic->i_u.compressed_blocks);
 		break;
 	default:
-		errln("unsupported on-disk inode version %u of nid %llu",
-		      __inode_version(ifmt), vi->nid);
+		erofs_err(inode->i_sb,
+			  "unsupported on-disk inode version %u of nid %llu",
+			  erofs_inode_version(ifmt), vi->nid);
 		err = -EOPNOTSUPP;
 		goto err_out;
 	}
@@ -158,12 +174,17 @@ static struct page *read_inode(struct inode *inode, unsigned int *ofs)
 	inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec;
 	inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec;
 
-	/* measure inode.i_blocks as the generic filesystem */
-	inode->i_blocks = ((inode->i_size - 1) >> 9) + 1;
+	if (!nblks)
+		/* measure inode.i_blocks as generic filesystems */
+		inode->i_blocks = roundup(inode->i_size, EROFS_BLKSIZ) >> 9;
+	else
+		inode->i_blocks = nblks << LOG_SECTORS_PER_BLOCK;
 	return page;
+
 bogusimode:
-	errln("bogus i_mode (%o) @ nid %llu", inode->i_mode, vi->nid);
-	err = -EIO;
+	erofs_err(inode->i_sb, "bogus i_mode (%o) @ nid %llu",
+		  inode->i_mode, vi->nid);
+	err = -EFSCORRUPTED;
 err_out:
 	DBG_BUGON(1);
 	kfree(copied);
@@ -172,56 +193,45 @@ err_out:
 	return ERR_PTR(err);
 }
 
-/*
- * try_lock can be required since locking order is:
- *   file data(fs_inode)
- *        meta(bd_inode)
- * but the majority of the callers is "iget",
- * in that case we are pretty sure no deadlock since
- * no data operations exist. However I tend to
- * try_lock since it takes no much overhead and
- * will success immediately.
- */
-static int fill_inline_data(struct inode *inode, void *data, unsigned m_pofs)
+static int erofs_fill_symlink(struct inode *inode, void *data,
+			      unsigned int m_pofs)
 {
-	struct erofs_vnode *vi = EROFS_V(inode);
-	struct erofs_sb_info *sbi = EROFS_I_SB(inode);
-	int mode = vi->data_mapping_mode;
-
-	DBG_BUGON(mode >= EROFS_INODE_LAYOUT_MAX);
+	struct erofs_inode *vi = EROFS_I(inode);
+	char *lnk;
 
-	/* should be inode inline C */
-	if (mode != EROFS_INODE_LAYOUT_INLINE)
+	/* if it cannot be handled with fast symlink scheme */
+	if (vi->datalayout != EROFS_INODE_FLAT_INLINE ||
+	    inode->i_size >= PAGE_SIZE) {
+		inode->i_op = &erofs_symlink_iops;
 		return 0;
+	}
 
-	/* fast symlink (following ext4) */
-	if (S_ISLNK(inode->i_mode) && inode->i_size < PAGE_SIZE) {
-		char *lnk = erofs_kmalloc(sbi, inode->i_size + 1, GFP_KERNEL);
-
-		if (unlikely(lnk == NULL))
-			return -ENOMEM;
-
-		m_pofs += vi->xattr_isize;
-
-		/* inline symlink data shouldn't across page boundary as well */
-		if (unlikely(m_pofs + inode->i_size > PAGE_SIZE)) {
-			DBG_BUGON(1);
-			kfree(lnk);
-			return -EIO;
-		}
+	lnk = kmalloc(inode->i_size + 1, GFP_KERNEL);
+	if (!lnk)
+		return -ENOMEM;
+
+	m_pofs += vi->xattr_isize;
+	/* inline symlink data shouldn't cross page boundary as well */
+	if (m_pofs + inode->i_size > PAGE_SIZE) {
+		kfree(lnk);
+		erofs_err(inode->i_sb,
+			  "inline data cross block boundary @ nid %llu",
+			  vi->nid);
+		DBG_BUGON(1);
+		return -EFSCORRUPTED;
+	}
 
-		/* get in-page inline data */
-		memcpy(lnk, data + m_pofs, inode->i_size);
-		lnk[inode->i_size] = '\0';
+	memcpy(lnk, data + m_pofs, inode->i_size);
+	lnk[inode->i_size] = '\0';
 
-		inode->i_link = lnk;
-		set_inode_fast_symlink(inode);
-	}
-	return -EAGAIN;
+	inode->i_link = lnk;
+	inode->i_op = &erofs_fast_symlink_iops;
+	return 0;
 }
 
-static int fill_inode(struct inode *inode, int isdir)
+static int erofs_fill_inode(struct inode *inode, int isdir)
 {
+	struct erofs_inode *vi = EROFS_I(inode);
 	struct page *page;
 	unsigned int ofs;
 	int err = 0;
@@ -229,59 +239,43 @@ static int fill_inode(struct inode *inode, int isdir)
 	trace_erofs_fill_inode(inode, isdir);
 
 	/* read inode base data from disk */
-	page = read_inode(inode, &ofs);
-	if (IS_ERR(page)) {
+	page = erofs_read_inode(inode, &ofs);
+	if (IS_ERR(page))
 		return PTR_ERR(page);
-	} else {
-		/* setup the new inode */
-		if (S_ISREG(inode->i_mode)) {
-#ifdef CONFIG_EROFS_FS_XATTR
-			inode->i_op = &erofs_generic_xattr_iops;
-#endif
-			inode->i_fop = &generic_ro_fops;
-		} else if (S_ISDIR(inode->i_mode)) {
-			inode->i_op =
-#ifdef CONFIG_EROFS_FS_XATTR
-				&erofs_dir_xattr_iops;
-#else
-				&erofs_dir_iops;
-#endif
-			inode->i_fop = &erofs_dir_fops;
-		} else if (S_ISLNK(inode->i_mode)) {
-			/* by default, page_get_link is used for symlink */
-			inode->i_op =
-#ifdef CONFIG_EROFS_FS_XATTR
-				&erofs_symlink_xattr_iops,
-#else
-				&page_symlink_inode_operations;
-#endif
-			inode_nohighmem(inode);
-		} else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
-			S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
-#ifdef CONFIG_EROFS_FS_XATTR
-			inode->i_op = &erofs_special_inode_operations;
-#endif
-			init_special_inode(inode, inode->i_mode, inode->i_rdev);
-		} else {
-			err = -EIO;
-			goto out_unlock;
-		}
 
-		if (is_inode_layout_compression(inode)) {
-#ifdef CONFIG_EROFS_FS_ZIP
-			inode->i_mapping->a_ops =
-				&z_erofs_vle_normalaccess_aops;
-#else
-			err = -ENOTSUPP;
-#endif
+	/* setup the new inode */
+	switch (inode->i_mode & S_IFMT) {
+	case S_IFREG:
+		inode->i_op = &erofs_generic_iops;
+		inode->i_fop = &generic_ro_fops;
+		break;
+	case S_IFDIR:
+		inode->i_op = &erofs_dir_iops;
+		inode->i_fop = &erofs_dir_fops;
+		break;
+	case S_IFLNK:
+		err = erofs_fill_symlink(inode, page_address(page), ofs);
+		if (err)
 			goto out_unlock;
-		}
-
-		inode->i_mapping->a_ops = &erofs_raw_access_aops;
+		inode_nohighmem(inode);
+		break;
+	case S_IFCHR:
+	case S_IFBLK:
+	case S_IFIFO:
+	case S_IFSOCK:
+		inode->i_op = &erofs_generic_iops;
+		init_special_inode(inode, inode->i_mode, inode->i_rdev);
+		goto out_unlock;
+	default:
+		err = -EFSCORRUPTED;
+		goto out_unlock;
+	}
 
-		/* fill last page if inline data is available */
-		fill_inline_data(inode, page_address(page), ofs);
+	if (erofs_inode_is_data_compressed(vi->datalayout)) {
+		err = z_erofs_fill_inode(inode);
+		goto out_unlock;
 	}
+	inode->i_mapping->a_ops = &erofs_raw_access_aops;
 
 out_unlock:
 	unlock_page(page);
@@ -289,21 +283,51 @@ out_unlock:
 	return err;
 }
 
+/*
+ * erofs nid is 64bits, but i_ino is 'unsigned long', therefore
+ * we should do more for 32-bit platform to find the right inode.
+ */
+static int erofs_ilookup_test_actor(struct inode *inode, void *opaque)
+{
+	const erofs_nid_t nid = *(erofs_nid_t *)opaque;
+
+	return EROFS_I(inode)->nid == nid;
+}
+
+static int erofs_iget_set_actor(struct inode *inode, void *opaque)
+{
+	const erofs_nid_t nid = *(erofs_nid_t *)opaque;
+
+	inode->i_ino = erofs_inode_hash(nid);
+	return 0;
+}
+
+static inline struct inode *erofs_iget_locked(struct super_block *sb,
+					      erofs_nid_t nid)
+{
+	const unsigned long hashval = erofs_inode_hash(nid);
+
+	return iget5_locked(sb, hashval, erofs_ilookup_test_actor,
+		erofs_iget_set_actor, &nid);
+}
+
 struct inode *erofs_iget(struct super_block *sb,
-	erofs_nid_t nid, bool isdir)
+			 erofs_nid_t nid,
+			 bool isdir)
 {
-	struct inode *inode = iget_locked(sb, nid);
+	struct inode *inode = erofs_iget_locked(sb, nid);
 
-	if (unlikely(inode == NULL))
+	if (!inode)
 		return ERR_PTR(-ENOMEM);
 
 	if (inode->i_state & I_NEW) {
 		int err;
-		struct erofs_vnode *vi = EROFS_V(inode);
+		struct erofs_inode *vi = EROFS_I(inode);
+
 		vi->nid = nid;
 
-		err = fill_inode(inode, isdir);
-		if (likely(!err))
+		err = erofs_fill_inode(inode, isdir);
+		if (!err)
 			unlock_new_inode(inode);
 		else {
 			iget_failed(inode);
@@ -313,29 +337,38 @@ struct inode *erofs_iget(struct super_block *sb,
 	return inode;
 }
 
-#ifdef CONFIG_EROFS_FS_XATTR
-const struct inode_operations erofs_generic_xattr_iops = {
-	.listxattr = erofs_listxattr,
-};
-#endif
+int erofs_getattr(const struct path *path, struct kstat *stat,
+		  u32 request_mask, unsigned int query_flags)
+{
+	struct inode *const inode = d_inode(path->dentry);
 
-#ifdef CONFIG_EROFS_FS_XATTR
-const struct inode_operations erofs_symlink_xattr_iops = {
-	.get_link = page_get_link,
+	if (erofs_inode_is_data_compressed(EROFS_I(inode)->datalayout))
+		stat->attributes |= STATX_ATTR_COMPRESSED;
+
+	stat->attributes |= STATX_ATTR_IMMUTABLE;
+	stat->attributes_mask |= (STATX_ATTR_COMPRESSED |
+				  STATX_ATTR_IMMUTABLE);
+
+	generic_fillattr(inode, stat);
+	return 0;
+}
+
+const struct inode_operations erofs_generic_iops = {
+	.getattr = erofs_getattr,
 	.listxattr = erofs_listxattr,
+	.get_acl = erofs_get_acl,
 };
-#endif
 
-const struct inode_operations erofs_special_inode_operations = {
-#ifdef CONFIG_EROFS_FS_XATTR
+const struct inode_operations erofs_symlink_iops = {
+	.get_link = page_get_link,
+	.getattr = erofs_getattr,
 	.listxattr = erofs_listxattr,
-#endif
+	.get_acl = erofs_get_acl,
 };
 
-#ifdef CONFIG_EROFS_FS_XATTR
-const struct inode_operations erofs_fast_symlink_xattr_iops = {
+const struct inode_operations erofs_fast_symlink_iops = {
 	.get_link = simple_get_link,
+	.getattr = erofs_getattr,
 	.listxattr = erofs_listxattr,
+	.get_acl = erofs_get_acl,
 };
-#endif
-
diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
index 8ce37091db20..5ee2368a18d5 100644
--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -1,17 +1,10 @@
-/* SPDX-License-Identifier: GPL-2.0
- *
- * linux/drivers/staging/erofs/internal.h
- *
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
  * Copyright (C) 2017-2018 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
+ *             https://www.huawei.com/
  */
-#ifndef __INTERNAL_H
-#define __INTERNAL_H
+#ifndef __EROFS_INTERNAL_H
+#define __EROFS_INTERNAL_H
 
 #include <linux/fs.h>
 #include <linux/dcache.h>
@@ -19,7 +12,7 @@
 #include <linux/pagemap.h>
 #include <linux/bio.h>
 #include <linux/buffer_head.h>
-#include <linux/cleancache.h>
+#include <linux/magic.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include "erofs_fs.h"
@@ -28,58 +21,50 @@
 #undef pr_fmt
 #define pr_fmt(fmt) "erofs: " fmt
 
-#define errln(x, ...)   pr_err(x "\n", ##__VA_ARGS__)
-#define infoln(x, ...)  pr_info(x "\n", ##__VA_ARGS__)
+__printf(3, 4) void _erofs_err(struct super_block *sb,
+			       const char *function, const char *fmt, ...);
+#define erofs_err(sb, fmt, ...)	\
+	_erofs_err(sb, __func__, fmt "\n", ##__VA_ARGS__)
+__printf(3, 4) void _erofs_info(struct super_block *sb,
+			       const char *function, const char *fmt, ...);
+#define erofs_info(sb, fmt, ...) \
+	_erofs_info(sb, __func__, fmt "\n", ##__VA_ARGS__)
 #ifdef CONFIG_EROFS_FS_DEBUG
-#define debugln(x, ...) pr_debug(x "\n", ##__VA_ARGS__)
-
-#define dbg_might_sleep         might_sleep
+#define erofs_dbg(x, ...)       pr_debug(x "\n", ##__VA_ARGS__)
 #define DBG_BUGON               BUG_ON
 #else
-#define debugln(x, ...)         ((void)0)
-
-#define dbg_might_sleep()       ((void)0)
+#define erofs_dbg(x, ...)       ((void)0)
 #define DBG_BUGON(x)            ((void)(x))
-#endif
-
-#ifdef CONFIG_EROFS_FAULT_INJECTION
-enum {
-	FAULT_KMALLOC,
-	FAULT_MAX,
-};
-
-extern char *erofs_fault_name[FAULT_MAX];
-#define IS_FAULT_SET(fi, type) ((fi)->inject_type & (1 << (type)))
-
-struct erofs_fault_info {
-	atomic_t inject_ops;
-	unsigned int inject_rate;
-	unsigned int inject_type;
-};
-#endif
-
-#ifdef CONFIG_EROFS_FS_ZIP_CACHE_BIPOLAR
-#define EROFS_FS_ZIP_CACHE_LVL	(2)
-#elif defined(EROFS_FS_ZIP_CACHE_UNIPOLAR)
-#define EROFS_FS_ZIP_CACHE_LVL	(1)
-#else
-#define EROFS_FS_ZIP_CACHE_LVL	(0)
-#endif
-
-#if (!defined(EROFS_FS_HAS_MANAGED_CACHE) && (EROFS_FS_ZIP_CACHE_LVL > 0))
-#define EROFS_FS_HAS_MANAGED_CACHE
-#endif
+#endif	/* !CONFIG_EROFS_FS_DEBUG */
 
 /* EROFS_SUPER_MAGIC_V1 to represent the whole file system */
 #define EROFS_SUPER_MAGIC   EROFS_SUPER_MAGIC_V1
 
 typedef u64 erofs_nid_t;
+typedef u64 erofs_off_t;
+/* data type for filesystem-wide blocks number */
+typedef u32 erofs_blk_t;
 
 struct erofs_sb_info {
+#ifdef CONFIG_EROFS_FS_ZIP
 	/* list for all registered superblocks, mainly for shrinker */
 	struct list_head list;
 	struct mutex umount_mutex;
 
+	/* the dedicated workstation for compression */
+	struct radix_tree_root workstn_tree;
+
+	/* threshold for decompression synchronously */
+	unsigned int max_sync_decompress_pages;
+
+	unsigned int shrinker_run_no;
+
+	/* current strategy of how to use managed cache */
+	unsigned char cache_strategy;
+
+	/* pseudo inode to manage cached pages */
+	struct inode *managed_cache;
+#endif	/* CONFIG_EROFS_FS_ZIP */
 	u32 blocks;
 	u32 meta_blkaddr;
 #ifdef CONFIG_EROFS_FS_XATTR
@@ -88,18 +73,6 @@ struct erofs_sb_info {
 
 	/* inode slot unit size in bit shift */
 	unsigned char islotbits;
-#ifdef CONFIG_EROFS_FS_ZIP
-	/* cluster size in bit shift */
-	unsigned char clusterbits;
-
-	/* the dedicated workstation for compression */
-	struct radix_tree_root workstn_tree;
-
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-	struct inode *managed_cache;
-#endif
-
-#endif
 
 	u32 build_time_nsec;
 	u64 build_time;
@@ -111,69 +84,31 @@ struct erofs_sb_info {
 
 	u8 uuid[16];                    /* 128-bit uuid for volume */
 	u8 volume_name[16];             /* volume name */
-	u32 requirements;
-
-	char *dev_name;
+	u32 feature_compat;
+	u32 feature_incompat;
 
 	unsigned int mount_opt;
-	unsigned int shrinker_run_no;
-
-#ifdef CONFIG_EROFS_FAULT_INJECTION
-	struct erofs_fault_info fault_info;	/* For fault injection */
-#endif
 };
 
-#ifdef CONFIG_EROFS_FAULT_INJECTION
-#define erofs_show_injection_info(type)					\
-	infoln("inject %s in %s of %pS", erofs_fault_name[type],        \
-		__func__, __builtin_return_address(0))
-
-static inline bool time_to_inject(struct erofs_sb_info *sbi, int type)
-{
-	struct erofs_fault_info *ffi = &sbi->fault_info;
-
-	if (!ffi->inject_rate)
-		return false;
-
-	if (!IS_FAULT_SET(ffi, type))
-		return false;
-
-	atomic_inc(&ffi->inject_ops);
-	if (atomic_read(&ffi->inject_ops) >= ffi->inject_rate) {
-		atomic_set(&ffi->inject_ops, 0);
-		return true;
-	}
-	return false;
-}
-#endif
-
-static inline void *erofs_kmalloc(struct erofs_sb_info *sbi,
-					size_t size, gfp_t flags)
-{
-#ifdef CONFIG_EROFS_FAULT_INJECTION
-	if (time_to_inject(sbi, FAULT_KMALLOC)) {
-		erofs_show_injection_info(FAULT_KMALLOC);
-		return NULL;
-	}
-#endif
-	return kmalloc(size, flags);
-}
-
 #define EROFS_SB(sb) ((struct erofs_sb_info *)(sb)->s_fs_info)
 #define EROFS_I_SB(inode) ((struct erofs_sb_info *)(inode)->i_sb->s_fs_info)
 
 /* Mount flags set via mount options or defaults */
 #define EROFS_MOUNT_XATTR_USER		0x00000010
 #define EROFS_MOUNT_POSIX_ACL		0x00000020
-#define EROFS_MOUNT_FAULT_INJECTION	0x00000040
 
 #define clear_opt(sbi, option)	((sbi)->mount_opt &= ~EROFS_MOUNT_##option)
 #define set_opt(sbi, option)	((sbi)->mount_opt |= EROFS_MOUNT_##option)
 #define test_opt(sbi, option)	((sbi)->mount_opt & EROFS_MOUNT_##option)
 
 #ifdef CONFIG_EROFS_FS_ZIP
-#define erofs_workstn_lock(sbi)         xa_lock(&(sbi)->workstn_tree)
-#define erofs_workstn_unlock(sbi)       xa_unlock(&(sbi)->workstn_tree)
+enum {
+	EROFS_ZIP_CACHE_DISABLED,
+	EROFS_ZIP_CACHE_READAHEAD,
+	EROFS_ZIP_CACHE_READAROUND
+};
+
+#define EROFS_LOCKED_MAGIC     (INT_MIN | 0xE0F510CCL)
 
 /* basic unit of the workstation of a super_block */
 struct erofs_workgroup {
@@ -184,8 +119,6 @@ struct erofs_workgroup {
 	atomic_t refcount;
 };
 
-#define EROFS_LOCKED_MAGIC     (INT_MIN | 0xE0F510CCL)
-
 #if defined(CONFIG_SMP)
 static inline bool erofs_workgroup_try_to_freeze(struct erofs_workgroup *grp,
 						 int val)
@@ -242,54 +175,14 @@ static inline int erofs_wait_on_workgroup_freezed(struct erofs_workgroup *grp)
 	DBG_BUGON(v == EROFS_LOCKED_MAGIC);
 	return v;
 }
-#endif
-
-static inline bool erofs_workgroup_get(struct erofs_workgroup *grp, int *ocnt)
-{
-	int o;
-
-repeat:
-	o = erofs_wait_on_workgroup_freezed(grp);
-
-	if (unlikely(o <= 0))
-		return -1;
-
-	if (unlikely(atomic_cmpxchg(&grp->refcount, o, o + 1) != o))
-		goto repeat;
-
-	*ocnt = o;
-	return 0;
-}
-
-#define __erofs_workgroup_get(grp)	atomic_inc(&(grp)->refcount)
-#define __erofs_workgroup_put(grp)	atomic_dec(&(grp)->refcount)
+#endif	/* !CONFIG_SMP */
 
-extern int erofs_workgroup_put(struct erofs_workgroup *grp);
-
-extern struct erofs_workgroup *erofs_find_workgroup(
-	struct super_block *sb, pgoff_t index, bool *tag);
-
-extern int erofs_register_workgroup(struct super_block *sb,
-	struct erofs_workgroup *grp, bool tag);
-
-extern unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi,
-	unsigned long nr_shrink, bool cleanup);
-
-static inline void erofs_workstation_cleanup_all(struct super_block *sb)
-{
-	erofs_shrink_workstation(EROFS_SB(sb), ~0UL, true);
-}
-
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-#define EROFS_UNALLOCATED_CACHED_PAGE	((void *)0x5F0EF00D)
-
-extern int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
-	struct erofs_workgroup *egrp);
-extern int erofs_try_to_free_cached_page(struct address_space *mapping,
-	struct page *page);
-#endif
-
-#endif
+/* hard limit of pages per compressed cluster */
+#define Z_EROFS_CLUSTER_MAX_PAGES       (CONFIG_EROFS_FS_CLUSTER_PAGE_LIMIT)
+#define EROFS_PCPUBUF_NR_PAGES          Z_EROFS_CLUSTER_MAX_PAGES
+#else
+#define EROFS_PCPUBUF_NR_PAGES          0
+#endif	/* !CONFIG_EROFS_FS_ZIP */
 
 /* we strictly follow PAGE_SIZE and no buffer head yet */
 #define LOG_BLOCK_SIZE		PAGE_SHIFT
@@ -308,19 +201,6 @@ extern int erofs_try_to_free_cached_page(struct address_space *mapping,
 
 #define ROOT_NID(sb)		((sb)->root_nid)
 
-#ifdef CONFIG_EROFS_FS_ZIP
-/* hard limit of pages per compressed cluster */
-#define Z_EROFS_CLUSTER_MAX_PAGES       (CONFIG_EROFS_FS_CLUSTER_PAGE_LIMIT)
-
-/* page count of a compressed cluster */
-#define erofs_clusterpages(sbi)         ((1 << (sbi)->clusterbits) / PAGE_SIZE)
-#endif
-
-typedef u64 erofs_off_t;
-
-/* data type for filesystem-wide blocks number */
-typedef u32 erofs_blk_t;
-
 #define erofs_blknr(addr)       ((addr) / EROFS_BLKSIZ)
 #define erofs_blkoff(addr)      ((addr) % EROFS_BLKSIZ)
 #define blknr_to_addr(nr)       ((erofs_off_t)(nr) * EROFS_BLKSIZ)
@@ -331,75 +211,74 @@ static inline erofs_off_t iloc(struct erofs_sb_info *sbi, erofs_nid_t nid)
 }
 
 /* atomic flag definitions */
-#define EROFS_V_EA_INITED_BIT	0
+#define EROFS_I_EA_INITED_BIT	0
+#define EROFS_I_Z_INITED_BIT	1
 
 /* bitlock definitions (arranged in reverse order) */
-#define EROFS_V_BL_XATTR_BIT	(BITS_PER_LONG - 1)
+#define EROFS_I_BL_XATTR_BIT	(BITS_PER_LONG - 1)
+#define EROFS_I_BL_Z_BIT	(BITS_PER_LONG - 2)
 
-struct erofs_vnode {
+struct erofs_inode {
 	erofs_nid_t nid;
 
 	/* atomic flags (including bitlocks) */
 	unsigned long flags;
 
-	unsigned char data_mapping_mode;
-	/* inline size in bytes */
+	unsigned char datalayout;
 	unsigned char inode_isize;
 	unsigned short xattr_isize;
 
-	unsigned xattr_shared_count;
-	unsigned *xattr_shared_xattrs;
-
-	erofs_blk_t raw_blkaddr;
+	unsigned int xattr_shared_count;
+	unsigned int *xattr_shared_xattrs;
 
+	union {
+		erofs_blk_t raw_blkaddr;
+#ifdef CONFIG_EROFS_FS_ZIP
+		struct {
+			unsigned short z_advise;
+			unsigned char  z_algorithmtype[2];
+			unsigned char  z_logical_clusterbits;
+			unsigned char  z_physical_clusterbits[2];
+		};
+#endif	/* CONFIG_EROFS_FS_ZIP */
+	};
 	/* the corresponding vfs inode */
 	struct inode vfs_inode;
 };
 
-#define EROFS_V(ptr)	\
-	container_of(ptr, struct erofs_vnode, vfs_inode)
-
-#define __inode_advise(x, bit, bits) \
-	(((x) >> (bit)) & ((1 << (bits)) - 1))
-
-#define __inode_version(advise)	\
-	__inode_advise(advise, EROFS_I_VERSION_BIT,	\
-		EROFS_I_VERSION_BITS)
-
-#define __inode_data_mapping(advise)	\
-	__inode_advise(advise, EROFS_I_DATA_MAPPING_BIT,\
-		EROFS_I_DATA_MAPPING_BITS)
+#define EROFS_I(ptr)	\
+	container_of(ptr, struct erofs_inode, vfs_inode)
 
-static inline unsigned long inode_datablocks(struct inode *inode)
+static inline unsigned long erofs_inode_datablocks(struct inode *inode)
 {
 	/* since i_size cannot be changed */
 	return DIV_ROUND_UP(inode->i_size, EROFS_BLKSIZ);
 }
 
-static inline bool is_inode_layout_plain(struct inode *inode)
+static inline unsigned int erofs_bitrange(unsigned int value, unsigned int bit,
+					  unsigned int bits)
 {
-	return EROFS_V(inode)->data_mapping_mode == EROFS_INODE_LAYOUT_PLAIN;
+
+	return (value >> bit) & ((1 << bits) - 1);
 }
 
-static inline bool is_inode_layout_compression(struct inode *inode)
+
+static inline unsigned int erofs_inode_version(unsigned int value)
 {
-	return EROFS_V(inode)->data_mapping_mode ==
-					EROFS_INODE_LAYOUT_COMPRESSION;
+	return erofs_bitrange(value, EROFS_I_VERSION_BIT,
+			      EROFS_I_VERSION_BITS);
 }
 
-static inline bool is_inode_layout_inline(struct inode *inode)
+static inline unsigned int erofs_inode_datalayout(unsigned int value)
 {
-	return EROFS_V(inode)->data_mapping_mode == EROFS_INODE_LAYOUT_INLINE;
+	return erofs_bitrange(value, EROFS_I_DATALAYOUT_BIT,
+			      EROFS_I_DATALAYOUT_BITS);
 }
 
 extern const struct super_operations erofs_sops;
-extern const struct inode_operations erofs_dir_iops;
-extern const struct file_operations erofs_dir_fops;
 
 extern const struct address_space_operations erofs_raw_access_aops;
-#ifdef CONFIG_EROFS_FS_ZIP
-extern const struct address_space_operations z_erofs_vle_normalaccess_aops;
-#endif
+extern const struct address_space_operations z_erofs_aops;
 
 /*
  * Logical to physical block mapping, used by erofs_map_blocks()
@@ -428,6 +307,7 @@ extern const struct address_space_operations z_erofs_vle_normalaccess_aops;
  */
 enum {
 	BH_Zipped = BH_PrivateStart,
+	BH_FullMapped,
 };
 
 /* Has a disk mapping */
@@ -436,150 +316,117 @@ enum {
 #define EROFS_MAP_META		(1 << BH_Meta)
 /* The extent has been compressed */
 #define EROFS_MAP_ZIPPED	(1 << BH_Zipped)
+/* The length of extent is full */
+#define EROFS_MAP_FULL_MAPPED	(1 << BH_FullMapped)
 
 struct erofs_map_blocks {
 	erofs_off_t m_pa, m_la;
 	u64 m_plen, m_llen;
 
 	unsigned int m_flags;
+
+	struct page *mpage;
 };
 
 /* Flags used by erofs_map_blocks() */
 #define EROFS_GET_BLOCKS_RAW    0x0001
 
-/* data.c */
-static inline struct bio *prepare_bio(
-	struct super_block *sb,
-	erofs_blk_t blkaddr, unsigned nr_pages,
-	bio_end_io_t endio)
-{
-	gfp_t gfp = GFP_NOIO;
-	struct bio *bio = bio_alloc(gfp, nr_pages);
-
-	if (unlikely(bio == NULL) &&
-		(current->flags & PF_MEMALLOC)) {
-		do {
-			nr_pages /= 2;
-			if (unlikely(!nr_pages)) {
-				bio = bio_alloc(gfp | __GFP_NOFAIL, 1);
-				BUG_ON(bio == NULL);
-				break;
-			}
-			bio = bio_alloc(gfp, nr_pages);
-		} while (bio == NULL);
-	}
-
-	bio->bi_end_io = endio;
-	bio_set_dev(bio, sb->s_bdev);
-	bio->bi_iter.bi_sector = blkaddr << LOG_SECTORS_PER_BLOCK;
-	return bio;
-}
-
-static inline void __submit_bio(struct bio *bio, unsigned op, unsigned op_flags)
+/* zmap.c */
+#ifdef CONFIG_EROFS_FS_ZIP
+int z_erofs_fill_inode(struct inode *inode);
+int z_erofs_map_blocks_iter(struct inode *inode,
+			    struct erofs_map_blocks *map,
+			    int flags);
+#else
+static inline int z_erofs_fill_inode(struct inode *inode) { return -EOPNOTSUPP; }
+static inline int z_erofs_map_blocks_iter(struct inode *inode,
+					  struct erofs_map_blocks *map,
+					  int flags)
 {
-	bio_set_op_attrs(bio, op, op_flags);
-	submit_bio(bio);
+	return -EOPNOTSUPP;
 }
+#endif	/* !CONFIG_EROFS_FS_ZIP */
 
-extern struct page *erofs_get_meta_page(struct super_block *sb,
-	erofs_blk_t blkaddr, bool prio);
-extern int erofs_map_blocks(struct inode *, struct erofs_map_blocks *, int);
-extern int erofs_map_blocks_iter(struct inode *, struct erofs_map_blocks *,
-	struct page **, int);
-
-struct erofs_map_blocks_iter {
-	struct erofs_map_blocks map;
-	struct page *mpage;
-};
+/* data.c */
+struct page *erofs_get_meta_page(struct super_block *sb, erofs_blk_t blkaddr);
 
+int erofs_map_blocks(struct inode *, struct erofs_map_blocks *, int);
 
-static inline struct page *
-erofs_get_inline_page(struct inode *inode,
-		      erofs_blk_t blkaddr)
+/* inode.c */
+static inline unsigned long erofs_inode_hash(erofs_nid_t nid)
 {
-	return erofs_get_meta_page(inode->i_sb,
-		blkaddr, S_ISDIR(inode->i_mode));
+#if BITS_PER_LONG == 32
+	return (nid >> 32) ^ (nid & 0xffffffff);
+#else
+	return nid;
+#endif
 }
 
-/* inode.c */
-extern struct inode *erofs_iget(struct super_block *sb,
-	erofs_nid_t nid, bool dir);
+extern const struct inode_operations erofs_generic_iops;
+extern const struct inode_operations erofs_symlink_iops;
+extern const struct inode_operations erofs_fast_symlink_iops;
+
+struct inode *erofs_iget(struct super_block *sb, erofs_nid_t nid, bool dir);
+int erofs_getattr(const struct path *path, struct kstat *stat,
+		  u32 request_mask, unsigned int query_flags);
+
+/* namei.c */
+extern const struct inode_operations erofs_dir_iops;
 
-/* dir.c */
 int erofs_namei(struct inode *dir, struct qstr *name,
-	erofs_nid_t *nid, unsigned *d_type);
+		erofs_nid_t *nid, unsigned int *d_type);
 
-/* xattr.c */
-#ifdef CONFIG_EROFS_FS_XATTR
-extern const struct xattr_handler *erofs_xattr_handlers[];
-#endif
+/* dir.c */
+extern const struct file_operations erofs_dir_fops;
 
-/* symlink */
-#ifdef CONFIG_EROFS_FS_XATTR
-extern const struct inode_operations erofs_symlink_xattr_iops;
-extern const struct inode_operations erofs_fast_symlink_xattr_iops;
-extern const struct inode_operations erofs_special_inode_operations;
-#endif
+/* utils.c / zdata.c */
+struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp);
 
-static inline void set_inode_fast_symlink(struct inode *inode)
-{
-#ifdef CONFIG_EROFS_FS_XATTR
-	inode->i_op = &erofs_fast_symlink_xattr_iops;
+#if (EROFS_PCPUBUF_NR_PAGES > 0)
+void *erofs_get_pcpubuf(unsigned int pagenr);
+#define erofs_put_pcpubuf(buf) do { \
+	(void)&(buf);	\
+	preempt_enable();	\
+} while (0)
 #else
-	inode->i_op = &simple_symlink_inode_operations;
-#endif
-}
-
-static inline bool is_inode_fast_symlink(struct inode *inode)
+static inline void *erofs_get_pcpubuf(unsigned int pagenr)
 {
-#ifdef CONFIG_EROFS_FS_XATTR
-	return inode->i_op == &erofs_fast_symlink_xattr_iops;
-#else
-	return inode->i_op == &simple_symlink_inode_operations;
-#endif
+	return ERR_PTR(-EOPNOTSUPP);
 }
 
-static inline void *erofs_vmap(struct page **pages, unsigned int count)
-{
-#ifdef CONFIG_EROFS_FS_USE_VM_MAP_RAM
-	int i = 0;
-
-	while (1) {
-		void *addr = vm_map_ram(pages, count, -1, PAGE_KERNEL);
-		/* retry two more times (totally 3 times) */
-		if (addr != NULL || ++i >= 3)
-			return addr;
-		vm_unmap_aliases();
-	}
-	return NULL;
-#else
-	return vmap(pages, count, VM_MAP, PAGE_KERNEL);
+#define erofs_put_pcpubuf(buf) do {} while (0)
 #endif
-}
 
-static inline void erofs_vunmap(const void *mem, unsigned int count)
-{
-#ifdef CONFIG_EROFS_FS_USE_VM_MAP_RAM
-	vm_unmap_ram(mem, count);
+#ifdef CONFIG_EROFS_FS_ZIP
+int erofs_workgroup_put(struct erofs_workgroup *grp);
+struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
+					     pgoff_t index);
+int erofs_register_workgroup(struct super_block *sb,
+			     struct erofs_workgroup *grp);
+void erofs_workgroup_free_rcu(struct erofs_workgroup *grp);
+void erofs_shrinker_register(struct super_block *sb);
+void erofs_shrinker_unregister(struct super_block *sb);
+int __init erofs_init_shrinker(void);
+void erofs_exit_shrinker(void);
+int __init z_erofs_init_zip_subsystem(void);
+void z_erofs_exit_zip_subsystem(void);
+int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
+				       struct erofs_workgroup *egrp);
+int erofs_try_to_free_cached_page(struct address_space *mapping,
+				  struct page *page);
 #else
-	vunmap(mem);
-#endif
-}
+static inline void erofs_shrinker_register(struct super_block *sb) {}
+static inline void erofs_shrinker_unregister(struct super_block *sb) {}
+static inline int erofs_init_shrinker(void) { return 0; }
+static inline void erofs_exit_shrinker(void) {}
+static inline int z_erofs_init_zip_subsystem(void) { return 0; }
+static inline void z_erofs_exit_zip_subsystem(void) {}
+#endif	/* !CONFIG_EROFS_FS_ZIP */
 
-/* utils.c */
-extern struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp);
-
-extern void erofs_register_super(struct super_block *sb);
-extern void erofs_unregister_super(struct super_block *sb);
-
-extern unsigned long erofs_shrink_count(struct shrinker *shrink,
-	struct shrink_control *sc);
-extern unsigned long erofs_shrink_scan(struct shrinker *shrink,
-	struct shrink_control *sc);
+#define EFSCORRUPTED    EUCLEAN         /* Filesystem is corrupted */
 
 #ifndef lru_to_page
 #define lru_to_page(head) (list_entry((head)->prev, struct page, lru))
 #endif
 
-#endif
-
+#endif	/* __EROFS_INTERNAL_H */
diff --git a/drivers/staging/erofs/lz4defs.h b/drivers/staging/erofs/lz4defs.h
deleted file mode 100644
index 00a0b58a0871..000000000000
--- a/drivers/staging/erofs/lz4defs.h
+++ /dev/null
@@ -1,227 +0,0 @@
-#ifndef __LZ4DEFS_H__
-#define __LZ4DEFS_H__
-
-/*
- * lz4defs.h -- common and architecture specific defines for the kernel usage
-
- * LZ4 - Fast LZ compression algorithm
- * Copyright (C) 2011-2016, Yann Collet.
- * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *	* Redistributions of source code must retain the above copyright
- *	  notice, this list of conditions and the following disclaimer.
- *	* Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- * You can contact the author at :
- *	- LZ4 homepage : http://www.lz4.org
- *	- LZ4 source repository : https://github.com/lz4/lz4
- *
- *	Changed for kernel usage by:
- *	Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
- */
-
-#include <asm/unaligned.h>
-#include <linux/string.h>	 /* memset, memcpy */
-
-#define FORCE_INLINE __always_inline
-
-/*-************************************
- *	Basic Types
- **************************************/
-#include <linux/types.h>
-
-typedef	uint8_t BYTE;
-typedef uint16_t U16;
-typedef uint32_t U32;
-typedef	int32_t S32;
-typedef uint64_t U64;
-typedef uintptr_t uptrval;
-
-/*-************************************
- *	Architecture specifics
- **************************************/
-#if defined(CONFIG_64BIT)
-#define LZ4_ARCH64 1
-#else
-#define LZ4_ARCH64 0
-#endif
-
-#if defined(__LITTLE_ENDIAN)
-#define LZ4_LITTLE_ENDIAN 1
-#else
-#define LZ4_LITTLE_ENDIAN 0
-#endif
-
-/*-************************************
- *	Constants
- **************************************/
-#define MINMATCH 4
-
-#define WILDCOPYLENGTH 8
-#define LASTLITERALS 5
-#define MFLIMIT (WILDCOPYLENGTH + MINMATCH)
-
-/* Increase this value ==> compression run slower on incompressible data */
-#define LZ4_SKIPTRIGGER 6
-
-#define HASH_UNIT sizeof(size_t)
-
-#define KB (1 << 10)
-#define MB (1 << 20)
-#define GB (1U << 30)
-
-#define MAXD_LOG 16
-#define MAX_DISTANCE ((1 << MAXD_LOG) - 1)
-#define STEPSIZE sizeof(size_t)
-
-#define ML_BITS	4
-#define ML_MASK	((1U << ML_BITS) - 1)
-#define RUN_BITS (8 - ML_BITS)
-#define RUN_MASK ((1U << RUN_BITS) - 1)
-
-/*-************************************
- *	Reading and writing into memory
- **************************************/
-static FORCE_INLINE U16 LZ4_read16(const void *ptr)
-{
-	return get_unaligned((const U16 *)ptr);
-}
-
-static FORCE_INLINE U32 LZ4_read32(const void *ptr)
-{
-	return get_unaligned((const U32 *)ptr);
-}
-
-static FORCE_INLINE size_t LZ4_read_ARCH(const void *ptr)
-{
-	return get_unaligned((const size_t *)ptr);
-}
-
-static FORCE_INLINE void LZ4_write16(void *memPtr, U16 value)
-{
-	put_unaligned(value, (U16 *)memPtr);
-}
-
-static FORCE_INLINE void LZ4_write32(void *memPtr, U32 value)
-{
-	put_unaligned(value, (U32 *)memPtr);
-}
-
-static FORCE_INLINE U16 LZ4_readLE16(const void *memPtr)
-{
-	return get_unaligned_le16(memPtr);
-}
-
-static FORCE_INLINE void LZ4_writeLE16(void *memPtr, U16 value)
-{
-	return put_unaligned_le16(value, memPtr);
-}
-
-static FORCE_INLINE void LZ4_copy8(void *dst, const void *src)
-{
-#if LZ4_ARCH64
-	U64 a = get_unaligned((const U64 *)src);
-
-	put_unaligned(a, (U64 *)dst);
-#else
-	U32 a = get_unaligned((const U32 *)src);
-	U32 b = get_unaligned((const U32 *)src + 1);
-
-	put_unaligned(a, (U32 *)dst);
-	put_unaligned(b, (U32 *)dst + 1);
-#endif
-}
-
-/*
- * customized variant of memcpy,
- * which can overwrite up to 7 bytes beyond dstEnd
- */
-static FORCE_INLINE void LZ4_wildCopy(void *dstPtr,
-	const void *srcPtr, void *dstEnd)
-{
-	BYTE *d = (BYTE *)dstPtr;
-	const BYTE *s = (const BYTE *)srcPtr;
-	BYTE *const e = (BYTE *)dstEnd;
-
-	do {
-		LZ4_copy8(d, s);
-		d += 8;
-		s += 8;
-	} while (d < e);
-}
-
-static FORCE_INLINE unsigned int LZ4_NbCommonBytes(register size_t val)
-{
-#if LZ4_LITTLE_ENDIAN
-	return __ffs(val) >> 3;
-#else
-	return (BITS_PER_LONG - 1 - __fls(val)) >> 3;
-#endif
-}
-
-static FORCE_INLINE unsigned int LZ4_count(
-	const BYTE *pIn,
-	const BYTE *pMatch,
-	const BYTE *pInLimit)
-{
-	const BYTE *const pStart = pIn;
-
-	while (likely(pIn < pInLimit - (STEPSIZE - 1))) {
-		size_t const diff = LZ4_read_ARCH(pMatch) ^ LZ4_read_ARCH(pIn);
-
-		if (!diff) {
-			pIn += STEPSIZE;
-			pMatch += STEPSIZE;
-			continue;
-		}
-
-		pIn += LZ4_NbCommonBytes(diff);
-
-		return (unsigned int)(pIn - pStart);
-	}
-
-#if LZ4_ARCH64
-	if ((pIn < (pInLimit - 3))
-		&& (LZ4_read32(pMatch) == LZ4_read32(pIn))) {
-		pIn += 4;
-		pMatch += 4;
-	}
-#endif
-
-	if ((pIn < (pInLimit - 1))
-		&& (LZ4_read16(pMatch) == LZ4_read16(pIn))) {
-		pIn += 2;
-		pMatch += 2;
-	}
-
-	if ((pIn < pInLimit) && (*pMatch == *pIn))
-		pIn++;
-
-	return (unsigned int)(pIn - pStart);
-}
-
-typedef enum { noLimit = 0, limitedOutput = 1 } limitedOutput_directive;
-typedef enum { byPtr, byU32, byU16 } tableType_t;
-
-typedef enum { noDict = 0, withPrefix64k, usingExtDict } dict_directive;
-typedef enum { noDictIssue = 0, dictSmall } dictIssue_directive;
-
-typedef enum { endOnOutputSize = 0, endOnInputSize = 1 } endCondition_directive;
-typedef enum { full = 0, partial = 1 } earlyEnd_directive;
-
-#endif
diff --git a/drivers/staging/erofs/namei.c b/drivers/staging/erofs/namei.c
index 023f64fa2c87..c5c0dd9d9033 100644
--- a/drivers/staging/erofs/namei.c
+++ b/drivers/staging/erofs/namei.c
@@ -1,16 +1,8 @@
-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
- * linux/drivers/staging/erofs/namei.c
- *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
+ *             https://www.huawei.com/
  */
-#include "internal.h"
 #include "xattr.h"
 
 #include <trace/events/erofs.h>
@@ -21,9 +13,9 @@ struct erofs_qstr {
 };
 
 /* based on the end of qn is accurate and it must have the trailing '\0' */
-static inline int dirnamecmp(const struct erofs_qstr *qn,
-			     const struct erofs_qstr *qd,
-			     unsigned int *matched)
+static inline int erofs_dirnamecmp(const struct erofs_qstr *qn,
+				   const struct erofs_qstr *qd,
+				   unsigned int *matched)
 {
 	unsigned int i = *matched;
 
@@ -71,16 +63,16 @@ static struct erofs_dirent *find_target_dirent(struct erofs_qstr *name,
 		unsigned int matched = min(startprfx, endprfx);
 		struct erofs_qstr dname = {
 			.name = data + nameoff,
-			.end = unlikely(mid >= ndirents - 1) ?
+			.end = mid >= ndirents - 1 ?
 				data + dirblksize :
 				data + nameoff_from_disk(de[mid + 1].nameoff,
 							 dirblksize)
 		};
 
 		/* string comparison without already matched prefix */
-		int ret = dirnamecmp(name, &dname, &matched);
+		int ret = erofs_dirnamecmp(name, &dname, &matched);
 
-		if (unlikely(!ret)) {
+		if (!ret) {
 			return de + mid;
 		} else if (ret > 0) {
 			head = mid + 1;
@@ -105,7 +97,7 @@ static struct page *find_target_block_classic(struct inode *dir,
 
 	startprfx = endprfx = 0;
 	head = 0;
-	back = inode_datablocks(dir) - 1;
+	back = erofs_inode_datablocks(dir) - 1;
 
 	while (head <= back) {
 		const int mid = head + (back - head) / 2;
@@ -120,11 +112,14 @@ static struct page *find_target_block_classic(struct inode *dir,
 			unsigned int matched;
 			struct erofs_qstr dname;
 
-			if (unlikely(!ndirents)) {
-				DBG_BUGON(1);
+			if (!ndirents) {
 				kunmap_atomic(de);
 				put_page(page);
-				page = ERR_PTR(-EIO);
+				erofs_err(dir->i_sb,
+					  "corrupted dir block %d @ nid %llu",
+					  mid, EROFS_I(dir)->nid);
+				DBG_BUGON(1);
+				page = ERR_PTR(-EFSCORRUPTED);
 				goto out;
 			}
 
@@ -139,17 +134,17 @@ static struct page *find_target_block_classic(struct inode *dir,
 							  EROFS_BLKSIZ);
 
 			/* string comparison without already matched prefix */
-			diff = dirnamecmp(name, &dname, &matched);
+			diff = erofs_dirnamecmp(name, &dname, &matched);
 			kunmap_atomic(de);
 
-			if (unlikely(!diff)) {
+			if (!diff) {
 				*_ndirents = 0;
 				goto out;
 			} else if (diff > 0) {
 				head = mid + 1;
 				startprfx = matched;
 
-				if (likely(!IS_ERR(candidate)))
+				if (!IS_ERR(candidate))
 					put_page(candidate);
 				candidate = page;
 				*_ndirents = ndirents;
@@ -179,7 +174,7 @@ int erofs_namei(struct inode *dir,
 	struct erofs_dirent *de;
 	struct erofs_qstr qn;
 
-	if (unlikely(!dir->i_size))
+	if (!dir->i_size)
 		return -ENOENT;
 
 	qn.name = name->name;
@@ -188,7 +183,7 @@ int erofs_namei(struct inode *dir,
 	ndirents = 0;
 	page = find_target_block_classic(dir, &qn, &ndirents);
 
-	if (unlikely(IS_ERR(page)))
+	if (IS_ERR(page))
 		return PTR_ERR(page);
 
 	data = kmap_atomic(page);
@@ -198,7 +193,7 @@ int erofs_namei(struct inode *dir,
 	else
 		de = (struct erofs_dirent *)data;
 
-	if (likely(!IS_ERR(de))) {
+	if (!IS_ERR(de)) {
 		*nid = le64_to_cpu(de->nid);
 		*d_type = de->file_type;
 	}
@@ -211,11 +206,12 @@ int erofs_namei(struct inode *dir,
 
 /* NOTE: i_mutex is already held by vfs */
 static struct dentry *erofs_lookup(struct inode *dir,
-	struct dentry *dentry, unsigned int flags)
+				   struct dentry *dentry,
+				   unsigned int flags)
 {
 	int err;
 	erofs_nid_t nid;
-	unsigned d_type;
+	unsigned int d_type;
 	struct inode *inode;
 
 	DBG_BUGON(!d_really_is_negative(dentry));
@@ -225,7 +221,7 @@ static struct dentry *erofs_lookup(struct inode *dir,
 	trace_erofs_lookup(dir, dentry, flags);
 
 	/* file name exceeds fs limit */
-	if (unlikely(dentry->d_name.len > EROFS_NAME_LEN))
+	if (dentry->d_name.len > EROFS_NAME_LEN)
 		return ERR_PTR(-ENAMETOOLONG);
 
 	/* false uninitialized warnings on gcc 4.8.x */
@@ -234,29 +230,19 @@ static struct dentry *erofs_lookup(struct inode *dir,
 	if (err == -ENOENT) {
 		/* negative dentry */
 		inode = NULL;
-		goto negative_out;
-	} else if (unlikely(err))
-		return ERR_PTR(err);
-
-	debugln("%s, %s (nid %llu) found, d_type %u", __func__,
-		dentry->d_name.name, nid, d_type);
-
-	inode = erofs_iget(dir->i_sb, nid, d_type == EROFS_FT_DIR);
-	if (IS_ERR(inode))
-		return ERR_CAST(inode);
-
-negative_out:
+	} else if (err) {
+		inode = ERR_PTR(err);
+	} else {
+		erofs_dbg("%s, %s (nid %llu) found, d_type %u", __func__,
+			  dentry->d_name.name, nid, d_type);
+		inode = erofs_iget(dir->i_sb, nid, d_type == EROFS_FT_DIR);
+	}
 	return d_splice_alias(inode, dentry);
 }
 
 const struct inode_operations erofs_dir_iops = {
 	.lookup = erofs_lookup,
-};
-
-const struct inode_operations erofs_dir_xattr_iops = {
-	.lookup = erofs_lookup,
-#ifdef CONFIG_EROFS_FS_XATTR
+	.getattr = erofs_getattr,
 	.listxattr = erofs_listxattr,
-#endif
+	.get_acl = erofs_get_acl,
 };
-
diff --git a/drivers/staging/erofs/super.c b/drivers/staging/erofs/super.c
index b49ebdf6ebda..13977976c719 100644
--- a/drivers/staging/erofs/super.c
+++ b/drivers/staging/erofs/super.c
@@ -1,188 +1,248 @@
-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
- * linux/drivers/staging/erofs/super.c
- *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
+ *             https://www.huawei.com/
  */
 #include <linux/module.h>
 #include <linux/buffer_head.h>
 #include <linux/statfs.h>
 #include <linux/parser.h>
 #include <linux/seq_file.h>
-#include "internal.h"
+#include <linux/crc32c.h>
+#include "xattr.h"
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/erofs.h>
 
 static struct kmem_cache *erofs_inode_cachep __read_mostly;
 
-static void init_once(void *ptr)
+void _erofs_err(struct super_block *sb, const char *function,
+		const char *fmt, ...)
 {
-	struct erofs_vnode *vi = ptr;
+	struct va_format vaf;
+	va_list args;
 
-	inode_init_once(&vi->vfs_inode);
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	pr_err("(device %s): %s: %pV", sb->s_id, function, &vaf);
+	va_end(args);
 }
 
-static int erofs_init_inode_cache(void)
+void _erofs_info(struct super_block *sb, const char *function,
+		 const char *fmt, ...)
 {
-	erofs_inode_cachep = kmem_cache_create("erofs_inode",
-		sizeof(struct erofs_vnode), 0,
-		SLAB_RECLAIM_ACCOUNT, init_once);
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
 
-	return erofs_inode_cachep != NULL ? 0 : -ENOMEM;
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	pr_info("(device %s): %pV", sb->s_id, &vaf);
+	va_end(args);
 }
 
-static void erofs_exit_inode_cache(void)
+static int erofs_superblock_csum_verify(struct super_block *sb, void *sbdata)
 {
-	kmem_cache_destroy(erofs_inode_cachep);
+	struct erofs_super_block *dsb;
+	u32 expected_crc, crc;
+
+	dsb = kmemdup(sbdata + EROFS_SUPER_OFFSET,
+		      EROFS_BLKSIZ - EROFS_SUPER_OFFSET, GFP_KERNEL);
+	if (!dsb)
+		return -ENOMEM;
+
+	expected_crc = le32_to_cpu(dsb->checksum);
+	dsb->checksum = 0;
+	/* to allow for x86 boot sectors and other oddities. */
+	crc = crc32c(~0, dsb, EROFS_BLKSIZ - EROFS_SUPER_OFFSET);
+	kfree(dsb);
+
+	if (crc != expected_crc) {
+		erofs_err(sb, "invalid checksum 0x%08x, 0x%08x expected",
+			  crc, expected_crc);
+		return -EBADMSG;
+	}
+	return 0;
 }
 
-static struct inode *alloc_inode(struct super_block *sb)
+static void erofs_inode_init_once(void *ptr)
 {
-	struct erofs_vnode *vi =
+	struct erofs_inode *vi = ptr;
+
+	inode_init_once(&vi->vfs_inode);
+}
+
+static struct inode *erofs_alloc_inode(struct super_block *sb)
+{
+	struct erofs_inode *vi =
 		kmem_cache_alloc(erofs_inode_cachep, GFP_KERNEL);
 
-	if (vi == NULL)
+	if (!vi)
 		return NULL;
 
 	/* zero out everything except vfs_inode */
-	memset(vi, 0, offsetof(struct erofs_vnode, vfs_inode));
+	memset(vi, 0, offsetof(struct erofs_inode, vfs_inode));
 	return &vi->vfs_inode;
 }
 
 static void i_callback(struct rcu_head *head)
 {
 	struct inode *inode = container_of(head, struct inode, i_rcu);
-	struct erofs_vnode *vi = EROFS_V(inode);
+	struct erofs_inode *vi = EROFS_I(inode);
 
-	/* be careful RCU symlink path (see ext4_inode_info->i_data)! */
-	if (is_inode_fast_symlink(inode))
+	/* be careful of RCU symlink path */
+	if (inode->i_op == &erofs_fast_symlink_iops)
 		kfree(inode->i_link);
-
 	kfree(vi->xattr_shared_xattrs);
 
 	kmem_cache_free(erofs_inode_cachep, vi);
 }
 
-static void destroy_inode(struct inode *inode)
+static void erofs_destroy_inode(struct inode *inode)
 {
 	call_rcu(&inode->i_rcu, i_callback);
 }
 
 static bool check_layout_compatibility(struct super_block *sb,
-				       struct erofs_super_block *layout)
+				       struct erofs_super_block *dsb)
 {
-	const unsigned int requirements = le32_to_cpu(layout->requirements);
+	const unsigned int feature = le32_to_cpu(dsb->feature_incompat);
 
-	EROFS_SB(sb)->requirements = requirements;
+	EROFS_SB(sb)->feature_incompat = feature;
 
 	/* check if current kernel meets all mandatory requirements */
-	if (requirements & (~EROFS_ALL_REQUIREMENTS)) {
-		errln("unidentified requirements %x, please upgrade kernel version",
-		      requirements & ~EROFS_ALL_REQUIREMENTS);
+	if (feature & (~EROFS_ALL_FEATURE_INCOMPAT)) {
+		erofs_err(sb,
+			  "unidentified incompatible feature %x, please upgrade kernel version",
+			   feature & ~EROFS_ALL_FEATURE_INCOMPAT);
 		return false;
 	}
 	return true;
 }
 
-static int superblock_read(struct super_block *sb)
+static int erofs_read_superblock(struct super_block *sb)
 {
 	struct erofs_sb_info *sbi;
-	struct buffer_head *bh;
-	struct erofs_super_block *layout;
-	unsigned blkszbits;
+	struct page *page;
+	struct erofs_super_block *dsb;
+	unsigned int blkszbits;
+	void *data;
 	int ret;
 
-	bh = sb_bread(sb, 0);
-
-	if (bh == NULL) {
-		errln("cannot read erofs superblock");
-		return -EIO;
+	page = read_mapping_page(sb->s_bdev->bd_inode->i_mapping, 0, NULL);
+	if (IS_ERR(page)) {
+		erofs_err(sb, "cannot read erofs superblock");
+		return PTR_ERR(page);
 	}
 
 	sbi = EROFS_SB(sb);
-	layout = (struct erofs_super_block *)((u8 *)bh->b_data
-		 + EROFS_SUPER_OFFSET);
+
+	data = kmap(page);
+	dsb = (struct erofs_super_block *)(data + EROFS_SUPER_OFFSET);
 
 	ret = -EINVAL;
-	if (le32_to_cpu(layout->magic) != EROFS_SUPER_MAGIC_V1) {
-		errln("cannot find valid erofs superblock");
+	if (le32_to_cpu(dsb->magic) != EROFS_SUPER_MAGIC_V1) {
+		erofs_err(sb, "cannot find valid erofs superblock");
 		goto out;
 	}
 
-	blkszbits = layout->blkszbits;
+	sbi->feature_compat = le32_to_cpu(dsb->feature_compat);
+	if (sbi->feature_compat & EROFS_FEATURE_COMPAT_SB_CHKSUM) {
+		ret = erofs_superblock_csum_verify(sb, data);
+		if (ret)
+			goto out;
+	}
+
+	ret = -EINVAL;
+	blkszbits = dsb->blkszbits;
 	/* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */
-	if (unlikely(blkszbits != LOG_BLOCK_SIZE)) {
-		errln("blksize %u isn't supported on this platform",
-			1 << blkszbits);
+	if (blkszbits != LOG_BLOCK_SIZE) {
+		erofs_err(sb, "blkszbits %u isn't supported on this platform",
+			  blkszbits);
 		goto out;
 	}
 
-	if (!check_layout_compatibility(sb, layout))
+	if (!check_layout_compatibility(sb, dsb))
 		goto out;
 
-	sbi->blocks = le32_to_cpu(layout->blocks);
-	sbi->meta_blkaddr = le32_to_cpu(layout->meta_blkaddr);
+	sbi->blocks = le32_to_cpu(dsb->blocks);
+	sbi->meta_blkaddr = le32_to_cpu(dsb->meta_blkaddr);
 #ifdef CONFIG_EROFS_FS_XATTR
-	sbi->xattr_blkaddr = le32_to_cpu(layout->xattr_blkaddr);
+	sbi->xattr_blkaddr = le32_to_cpu(dsb->xattr_blkaddr);
 #endif
-	sbi->islotbits = ffs(sizeof(struct erofs_inode_v1)) - 1;
-#ifdef CONFIG_EROFS_FS_ZIP
-	sbi->clusterbits = 12;
-
-	if (1 << (sbi->clusterbits - 12) > Z_EROFS_CLUSTER_MAX_PAGES)
-		errln("clusterbits %u is not supported on this kernel",
-			sbi->clusterbits);
-#endif
-
-	sbi->root_nid = le16_to_cpu(layout->root_nid);
-	sbi->inos = le64_to_cpu(layout->inos);
+	sbi->islotbits = ilog2(sizeof(struct erofs_inode_compact));
+	sbi->root_nid = le16_to_cpu(dsb->root_nid);
+	sbi->inos = le64_to_cpu(dsb->inos);
 
-	sbi->build_time = le64_to_cpu(layout->build_time);
-	sbi->build_time_nsec = le32_to_cpu(layout->build_time_nsec);
+	sbi->build_time = le64_to_cpu(dsb->build_time);
+	sbi->build_time_nsec = le32_to_cpu(dsb->build_time_nsec);
 
-	memcpy(&sb->s_uuid, layout->uuid, sizeof(layout->uuid));
-	memcpy(sbi->volume_name, layout->volume_name,
-		sizeof(layout->volume_name));
+	memcpy(&sb->s_uuid, dsb->uuid, sizeof(dsb->uuid));
 
+	ret = strscpy(sbi->volume_name, dsb->volume_name,
+		      sizeof(dsb->volume_name));
+	if (ret < 0) {	/* -E2BIG */
+		erofs_err(sb, "bad volume name without NIL terminator");
+		ret = -EFSCORRUPTED;
+		goto out;
+	}
 	ret = 0;
 out:
-	brelse(bh);
+	kunmap(page);
+	put_page(page);
 	return ret;
 }
 
-#ifdef CONFIG_EROFS_FAULT_INJECTION
-char *erofs_fault_name[FAULT_MAX] = {
-	[FAULT_KMALLOC]		= "kmalloc",
-};
-
-static void erofs_build_fault_attr(struct erofs_sb_info *sbi,
-						unsigned int rate)
+#ifdef CONFIG_EROFS_FS_ZIP
+static int erofs_build_cache_strategy(struct super_block *sb,
+				      substring_t *args)
 {
-	struct erofs_fault_info *ffi = &sbi->fault_info;
+	struct erofs_sb_info *sbi = EROFS_SB(sb);
+	const char *cs = match_strdup(args);
+	int err = 0;
 
-	if (rate) {
-		atomic_set(&ffi->inject_ops, 0);
-		ffi->inject_rate = rate;
-		ffi->inject_type = (1 << FAULT_MAX) - 1;
+	if (!cs) {
+		erofs_err(sb, "Not enough memory to store cache strategy");
+		return -ENOMEM;
+	}
+
+	if (!strcmp(cs, "disabled")) {
+		sbi->cache_strategy = EROFS_ZIP_CACHE_DISABLED;
+	} else if (!strcmp(cs, "readahead")) {
+		sbi->cache_strategy = EROFS_ZIP_CACHE_READAHEAD;
+	} else if (!strcmp(cs, "readaround")) {
+		sbi->cache_strategy = EROFS_ZIP_CACHE_READAROUND;
 	} else {
-		memset(ffi, 0, sizeof(struct erofs_fault_info));
+		erofs_err(sb, "Unrecognized cache strategy \"%s\"", cs);
+		err = -EINVAL;
 	}
+	kfree(cs);
+	return err;
+}
+#else
+static int erofs_build_cache_strategy(struct super_block *sb,
+				      substring_t *args)
+{
+	erofs_info(sb, "EROFS compression is disabled, so cache strategy is ignored");
+	return 0;
 }
 #endif
 
-static void default_options(struct erofs_sb_info *sbi)
+/* set up default EROFS parameters */
+static void erofs_default_options(struct erofs_sb_info *sbi)
 {
+#ifdef CONFIG_EROFS_FS_ZIP
+	sbi->cache_strategy = EROFS_ZIP_CACHE_READAROUND;
+	sbi->max_sync_decompress_pages = 3;
+#endif
 #ifdef CONFIG_EROFS_FS_XATTR
 	set_opt(sbi, XATTR_USER);
 #endif
-
 #ifdef CONFIG_EROFS_FS_POSIX_ACL
 	set_opt(sbi, POSIX_ACL);
 #endif
@@ -193,7 +253,7 @@ enum {
 	Opt_nouser_xattr,
 	Opt_acl,
 	Opt_noacl,
-	Opt_fault_injection,
+	Opt_cache_strategy,
 	Opt_err
 };
 
@@ -202,20 +262,20 @@ static match_table_t erofs_tokens = {
 	{Opt_nouser_xattr, "nouser_xattr"},
 	{Opt_acl, "acl"},
 	{Opt_noacl, "noacl"},
-	{Opt_fault_injection, "fault_injection=%u"},
+	{Opt_cache_strategy, "cache_strategy=%s"},
 	{Opt_err, NULL}
 };
 
-static int parse_options(struct super_block *sb, char *options)
+static int erofs_parse_options(struct super_block *sb, char *options)
 {
 	substring_t args[MAX_OPT_ARGS];
 	char *p;
-	int arg = 0;
+	int err;
 
 	if (!options)
 		return 0;
 
-	while ((p = strsep(&options, ",")) != NULL) {
+	while ((p = strsep(&options, ","))) {
 		int token;
 
 		if (!*p)
@@ -234,10 +294,10 @@ static int parse_options(struct super_block *sb, char *options)
 			break;
 #else
 		case Opt_user_xattr:
-			infoln("user_xattr options not supported");
+			erofs_info(sb, "user_xattr options not supported");
 			break;
 		case Opt_nouser_xattr:
-			infoln("nouser_xattr options not supported");
+			erofs_info(sb, "nouser_xattr options not supported");
 			break;
 #endif
 #ifdef CONFIG_EROFS_FS_POSIX_ACL
@@ -249,36 +309,29 @@ static int parse_options(struct super_block *sb, char *options)
 			break;
 #else
 		case Opt_acl:
-			infoln("acl options not supported");
+			erofs_info(sb, "acl options not supported");
 			break;
 		case Opt_noacl:
-			infoln("noacl options not supported");
+			erofs_info(sb, "noacl options not supported");
 			break;
 #endif
-		case Opt_fault_injection:
-			if (args->from && match_int(args, &arg))
-				return -EINVAL;
-#ifdef CONFIG_EROFS_FAULT_INJECTION
-			erofs_build_fault_attr(EROFS_SB(sb), arg);
-			set_opt(EROFS_SB(sb), FAULT_INJECTION);
-#else
-			infoln("FAULT_INJECTION was not selected");
-#endif
+		case Opt_cache_strategy:
+			err = erofs_build_cache_strategy(sb, args);
+			if (err)
+				return err;
 			break;
 		default:
-			errln("Unrecognized mount option \"%s\" "
-					"or missing value", p);
+			erofs_err(sb, "Unrecognized mount option \"%s\" or missing value", p);
 			return -EINVAL;
 		}
 	}
 	return 0;
 }
 
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-
+#ifdef CONFIG_EROFS_FS_ZIP
 static const struct address_space_operations managed_cache_aops;
 
-static int managed_cache_releasepage(struct page *page, gfp_t gfp_mask)
+static int erofs_managed_cache_releasepage(struct page *page, gfp_t gfp_mask)
 {
 	int ret = 1;	/* 0 - busy */
 	struct address_space *const mapping = page->mapping;
@@ -292,8 +345,9 @@ static int managed_cache_releasepage(struct page *page, gfp_t gfp_mask)
 	return ret;
 }
 
-static void managed_cache_invalidatepage(struct page *page,
-	unsigned int offset, unsigned int length)
+static void erofs_managed_cache_invalidatepage(struct page *page,
+					       unsigned int offset,
+					       unsigned int length)
 {
 	const unsigned int stop = length + offset;
 
@@ -303,227 +357,147 @@ static void managed_cache_invalidatepage(struct page *page,
 	DBG_BUGON(stop > PAGE_SIZE || stop < length);
 
 	if (offset == 0 && stop == PAGE_SIZE)
-		while (!managed_cache_releasepage(page, GFP_NOFS))
+		while (!erofs_managed_cache_releasepage(page, GFP_NOFS))
 			cond_resched();
 }
 
 static const struct address_space_operations managed_cache_aops = {
-	.releasepage = managed_cache_releasepage,
-	.invalidatepage = managed_cache_invalidatepage,
+	.releasepage = erofs_managed_cache_releasepage,
+	.invalidatepage = erofs_managed_cache_invalidatepage,
 };
 
-static struct inode *erofs_init_managed_cache(struct super_block *sb)
+static int erofs_init_managed_cache(struct super_block *sb)
 {
-	struct inode *inode = new_inode(sb);
+	struct erofs_sb_info *const sbi = EROFS_SB(sb);
+	struct inode *const inode = new_inode(sb);
 
-	if (unlikely(inode == NULL))
-		return ERR_PTR(-ENOMEM);
+	if (!inode)
+		return -ENOMEM;
 
 	set_nlink(inode, 1);
 	inode->i_size = OFFSET_MAX;
 
 	inode->i_mapping->a_ops = &managed_cache_aops;
 	mapping_set_gfp_mask(inode->i_mapping,
-			     GFP_NOFS | __GFP_HIGHMEM |
-			     __GFP_MOVABLE |  __GFP_NOFAIL);
-	return inode;
+			     GFP_NOFS | __GFP_HIGHMEM | __GFP_MOVABLE);
+	sbi->managed_cache = inode;
+	return 0;
 }
-
+#else
+static int erofs_init_managed_cache(struct super_block *sb) { return 0; }
 #endif
 
-static int erofs_read_super(struct super_block *sb,
-	const char *dev_name, void *data, int silent)
+static int erofs_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct inode *inode;
 	struct erofs_sb_info *sbi;
-	int err = -EINVAL;
+	int err;
 
-	infoln("read_super, device -> %s", dev_name);
-	infoln("options -> %s", (char *)data);
+	sb->s_magic = EROFS_SUPER_MAGIC;
 
-	if (unlikely(!sb_set_blocksize(sb, EROFS_BLKSIZ))) {
-		errln("failed to set erofs blksize");
-		goto err;
+	if (!sb_set_blocksize(sb, EROFS_BLKSIZ)) {
+		erofs_err(sb, "failed to set erofs blksize");
+		return -EINVAL;
 	}
 
-	sbi = kzalloc(sizeof(struct erofs_sb_info), GFP_KERNEL);
-	if (unlikely(sbi == NULL)) {
-		err = -ENOMEM;
-		goto err;
-	}
-	sb->s_fs_info = sbi;
+	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
+	if (!sbi)
+		return -ENOMEM;
 
-	err = superblock_read(sb);
+	sb->s_fs_info = sbi;
+	err = erofs_read_superblock(sb);
 	if (err)
-		goto err_sbread;
+		return err;
 
-	sb->s_magic = EROFS_SUPER_MAGIC;
 	sb->s_flags |= SB_RDONLY | SB_NOATIME;
 	sb->s_maxbytes = MAX_LFS_FILESIZE;
 	sb->s_time_gran = 1;
 
 	sb->s_op = &erofs_sops;
-
-#ifdef CONFIG_EROFS_FS_XATTR
 	sb->s_xattr = erofs_xattr_handlers;
-#endif
 
 	/* set erofs default mount options */
-	default_options(sbi);
+	erofs_default_options(sbi);
 
-	err = parse_options(sb, data);
+	err = erofs_parse_options(sb, data);
 	if (err)
-		goto err_parseopt;
+		return err;
 
-	if (!silent)
-		infoln("root inode @ nid %llu", ROOT_NID(sbi));
+	if (test_opt(sbi, POSIX_ACL))
+		sb->s_flags |= SB_POSIXACL;
+	else
+		sb->s_flags &= ~SB_POSIXACL;
 
 #ifdef CONFIG_EROFS_FS_ZIP
 	INIT_RADIX_TREE(&sbi->workstn_tree, GFP_ATOMIC);
 #endif
 
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-	sbi->managed_cache = erofs_init_managed_cache(sb);
-	if (IS_ERR(sbi->managed_cache)) {
-		err = PTR_ERR(sbi->managed_cache);
-		goto err_init_managed_cache;
-	}
-#endif
-
 	/* get the root inode */
 	inode = erofs_iget(sb, ROOT_NID(sbi), true);
-	if (IS_ERR(inode)) {
-		err = PTR_ERR(inode);
-		goto err_iget;
-	}
+	if (IS_ERR(inode))
+		return PTR_ERR(inode);
 
 	if (!S_ISDIR(inode->i_mode)) {
-		errln("rootino(nid %llu) is not a directory(i_mode %o)",
-			ROOT_NID(sbi), inode->i_mode);
-		err = -EINVAL;
-		goto err_isdir;
+		erofs_err(sb, "rootino(nid %llu) is not a directory(i_mode %o)",
+			  ROOT_NID(sbi), inode->i_mode);
+		iput(inode);
+		return -EINVAL;
 	}
 
 	sb->s_root = d_make_root(inode);
-	if (sb->s_root == NULL) {
-		err = -ENOMEM;
-		goto err_makeroot;
-	}
-
-	/* save the device name to sbi */
-	sbi->dev_name = __getname();
-	if (sbi->dev_name == NULL) {
-		err = -ENOMEM;
-		goto err_devname;
-	}
-
-	snprintf(sbi->dev_name, PATH_MAX, "%s", dev_name);
-	sbi->dev_name[PATH_MAX - 1] = '\0';
+	if (!sb->s_root)
+		return -ENOMEM;
 
-	erofs_register_super(sb);
+	erofs_shrinker_register(sb);
+	/* sb->s_umount is already locked, SB_ACTIVE and SB_BORN are not set */
+	err = erofs_init_managed_cache(sb);
+	if (err)
+		return err;
 
-	if (!silent)
-		infoln("mounted on %s with opts: %s.", dev_name,
-			(char *)data);
+	erofs_info(sb, "mounted with opts: %s, root inode @ nid %llu.",
+		   (char *)data, ROOT_NID(sbi));
 	return 0;
-	/*
-	 * please add a label for each exit point and use
-	 * the following name convention, thus new features
-	 * can be integrated easily without renaming labels.
-	 */
-err_devname:
-	dput(sb->s_root);
-err_makeroot:
-err_isdir:
-	if (sb->s_root == NULL)
-		iput(inode);
-err_iget:
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-	iput(sbi->managed_cache);
-err_init_managed_cache:
-#endif
-err_parseopt:
-err_sbread:
-	sb->s_fs_info = NULL;
-	kfree(sbi);
-err:
-	return err;
+}
+
+static struct dentry *erofs_mount(struct file_system_type *fs_type, int flags,
+				  const char *dev_name, void *data)
+{
+	return mount_bdev(fs_type, flags, dev_name, data, erofs_fill_super);
 }
 
 /*
  * could be triggered after deactivate_locked_super()
  * is called, thus including umount and failed to initialize.
  */
-static void erofs_put_super(struct super_block *sb)
+static void erofs_kill_sb(struct super_block *sb)
 {
-	struct erofs_sb_info *sbi = EROFS_SB(sb);
-
-	/* for cases which are failed in "read_super" */
-	if (sbi == NULL)
-		return;
+	struct erofs_sb_info *sbi;
 
 	WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC);
 
-	infoln("unmounted for %s", sbi->dev_name);
-	__putname(sbi->dev_name);
-
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-	iput(sbi->managed_cache);
-#endif
-
-	mutex_lock(&sbi->umount_mutex);
-
-#ifdef CONFIG_EROFS_FS_ZIP
-	erofs_workstation_cleanup_all(sb);
-#endif
-
-	erofs_unregister_super(sb);
-	mutex_unlock(&sbi->umount_mutex);
+	kill_block_super(sb);
 
+	sbi = EROFS_SB(sb);
+	if (!sbi)
+		return;
 	kfree(sbi);
 	sb->s_fs_info = NULL;
 }
 
-
-struct erofs_mount_private {
-	const char *dev_name;
-	char *options;
-};
-
-/* support mount_bdev() with options */
-static int erofs_fill_super(struct super_block *sb,
-	void *_priv, int silent)
-{
-	struct erofs_mount_private *priv = _priv;
-
-	return erofs_read_super(sb, priv->dev_name,
-		priv->options, silent);
-}
-
-static struct dentry *erofs_mount(
-	struct file_system_type *fs_type, int flags,
-	const char *dev_name, void *data)
+/* called when ->s_root is non-NULL */
+static void erofs_put_super(struct super_block *sb)
 {
-	struct erofs_mount_private priv = {
-		.dev_name = dev_name,
-		.options = data
-	};
+	struct erofs_sb_info *const sbi = EROFS_SB(sb);
 
-	return mount_bdev(fs_type, flags, dev_name,
-		&priv, erofs_fill_super);
-}
+	DBG_BUGON(!sbi);
 
-static void erofs_kill_sb(struct super_block *sb)
-{
-	kill_block_super(sb);
+	erofs_shrinker_unregister(sb);
+#ifdef CONFIG_EROFS_FS_ZIP
+	iput(sbi->managed_cache);
+	sbi->managed_cache = NULL;
+#endif
 }
 
-static struct shrinker erofs_shrinker_info = {
-	.scan_objects = erofs_shrink_scan,
-	.count_objects = erofs_shrink_count,
-	.seeks = DEFAULT_SEEKS,
-};
-
 static struct file_system_type erofs_fs_type = {
 	.owner          = THIS_MODULE,
 	.name           = "erofs",
@@ -533,47 +507,41 @@ static struct file_system_type erofs_fs_type = {
 };
 MODULE_ALIAS_FS("erofs");
 
-#ifdef CONFIG_EROFS_FS_ZIP
-extern int z_erofs_init_zip_subsystem(void);
-extern void z_erofs_exit_zip_subsystem(void);
-#endif
-
 static int __init erofs_module_init(void)
 {
 	int err;
 
 	erofs_check_ondisk_layout_definitions();
-	infoln("initializing erofs " EROFS_VERSION);
 
-	err = erofs_init_inode_cache();
-	if (err)
+	erofs_inode_cachep = kmem_cache_create("erofs_inode",
+					       sizeof(struct erofs_inode), 0,
+					       SLAB_RECLAIM_ACCOUNT,
+					       erofs_inode_init_once);
+	if (!erofs_inode_cachep) {
+		err = -ENOMEM;
 		goto icache_err;
+	}
 
-	err = register_shrinker(&erofs_shrinker_info);
+	err = erofs_init_shrinker();
 	if (err)
 		goto shrinker_err;
 
-#ifdef CONFIG_EROFS_FS_ZIP
 	err = z_erofs_init_zip_subsystem();
 	if (err)
 		goto zip_err;
-#endif
 
 	err = register_filesystem(&erofs_fs_type);
 	if (err)
 		goto fs_err;
 
-	infoln("successfully to initialize erofs");
 	return 0;
 
 fs_err:
-#ifdef CONFIG_EROFS_FS_ZIP
 	z_erofs_exit_zip_subsystem();
 zip_err:
-#endif
-	unregister_shrinker(&erofs_shrinker_info);
+	erofs_exit_shrinker();
 shrinker_err:
-	erofs_exit_inode_cache();
+	kmem_cache_destroy(erofs_inode_cachep);
 icache_err:
 	return err;
 }
@@ -581,12 +549,12 @@ icache_err:
 static void __exit erofs_module_exit(void)
 {
 	unregister_filesystem(&erofs_fs_type);
-#ifdef CONFIG_EROFS_FS_ZIP
 	z_erofs_exit_zip_subsystem();
-#endif
-	unregister_shrinker(&erofs_shrinker_info);
-	erofs_exit_inode_cache();
-	infoln("successfully finalize erofs");
+	erofs_exit_shrinker();
+
+	/* Ensure all RCU free inodes are safe before cache is destroyed. */
+	rcu_barrier();
+	kmem_cache_destroy(erofs_inode_cachep);
 }
 
 /* get filesystem statistics */
@@ -627,26 +595,45 @@ static int erofs_show_options(struct seq_file *seq, struct dentry *root)
 	else
 		seq_puts(seq, ",noacl");
 #endif
-#ifdef CONFIG_EROFS_FAULT_INJECTION
-	if (test_opt(sbi, FAULT_INJECTION))
-		seq_printf(seq, ",fault_injection=%u",
-				sbi->fault_info.inject_rate);
+#ifdef CONFIG_EROFS_FS_ZIP
+	if (sbi->cache_strategy == EROFS_ZIP_CACHE_DISABLED) {
+		seq_puts(seq, ",cache_strategy=disabled");
+	} else if (sbi->cache_strategy == EROFS_ZIP_CACHE_READAHEAD) {
+		seq_puts(seq, ",cache_strategy=readahead");
+	} else if (sbi->cache_strategy == EROFS_ZIP_CACHE_READAROUND) {
+		seq_puts(seq, ",cache_strategy=readaround");
+	}
 #endif
 	return 0;
 }
 
 static int erofs_remount(struct super_block *sb, int *flags, char *data)
 {
+	struct erofs_sb_info *sbi = EROFS_SB(sb);
+	unsigned int org_mnt_opt = sbi->mount_opt;
+	int err;
+
 	DBG_BUGON(!sb_rdonly(sb));
+	err = erofs_parse_options(sb, data);
+	if (err)
+		goto out;
+
+	if (test_opt(sbi, POSIX_ACL))
+		sb->s_flags |= SB_POSIXACL;
+	else
+		sb->s_flags &= ~SB_POSIXACL;
 
 	*flags |= SB_RDONLY;
 	return 0;
+out:
+	sbi->mount_opt = org_mnt_opt;
+	return err;
 }
 
 const struct super_operations erofs_sops = {
 	.put_super = erofs_put_super,
-	.alloc_inode = alloc_inode,
-	.destroy_inode = destroy_inode,
+	.alloc_inode = erofs_alloc_inode,
+	.destroy_inode = erofs_destroy_inode,
 	.statfs = erofs_statfs,
 	.show_options = erofs_show_options,
 	.remount_fs = erofs_remount,
@@ -656,6 +643,5 @@ module_init(erofs_module_init);
 module_exit(erofs_module_exit);
 
 MODULE_DESCRIPTION("Enhanced ROM File System");
-MODULE_AUTHOR("Gao Xiang, Yu Chao, Miao Xie, CONSUMER BG, HUAWEI Inc.");
+MODULE_AUTHOR("Gao Xiang, Chao Yu, Miao Xie, CONSUMER BG, HUAWEI Inc.");
 MODULE_LICENSE("GPL");
-
diff --git a/drivers/staging/erofs/include/linux/tagptr.h b/drivers/staging/erofs/tagptr.h
similarity index 93%
rename from drivers/staging/erofs/include/linux/tagptr.h
rename to drivers/staging/erofs/tagptr.h
index ccd106dbd48e..64ceb7270b5c 100644
--- a/drivers/staging/erofs/include/linux/tagptr.h
+++ b/drivers/staging/erofs/tagptr.h
@@ -1,11 +1,9 @@
-/* SPDX-License-Identifier: GPL-2.0
- *
- * Tagged pointer implementation
- *
- * Copyright (C) 2018 Gao Xiang <gaoxiang25@huawei.com>
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * A tagged pointer implementation
  */
-#ifndef _LINUX_TAGPTR_H
-#define _LINUX_TAGPTR_H
+#ifndef __EROFS_FS_TAGPTR_H
+#define __EROFS_FS_TAGPTR_H
 
 #include <linux/types.h>
 #include <linux/build_bug.h>
@@ -106,5 +104,4 @@ tagptr_init(o, cmpxchg(&ptptr->v, o.v, n.v)); })
 	ptptr->v &= ~tags; \
 *ptptr; })
 
-#endif
-
+#endif	/* __EROFS_FS_TAGPTR_H */
diff --git a/drivers/staging/erofs/unzip_lz4.c b/drivers/staging/erofs/unzip_lz4.c
deleted file mode 100644
index b1ea23f66c4e..000000000000
--- a/drivers/staging/erofs/unzip_lz4.c
+++ /dev/null
@@ -1,251 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
-/*
- * linux/drivers/staging/erofs/unzip_lz4.c
- *
- * Copyright (C) 2018 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * Original code taken from 'linux/lib/lz4/lz4_decompress.c'
- */
-
-/*
- * LZ4 - Fast LZ compression algorithm
- * Copyright (C) 2011 - 2016, Yann Collet.
- * BSD 2 - Clause License (http://www.opensource.org/licenses/bsd - license.php)
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *	* Redistributions of source code must retain the above copyright
- *	  notice, this list of conditions and the following disclaimer.
- *	* Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- * You can contact the author at :
- *	- LZ4 homepage : http://www.lz4.org
- *	- LZ4 source repository : https://github.com/lz4/lz4
- *
- *	Changed for kernel usage by:
- *	Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
- */
-#include "internal.h"
-#include <asm/unaligned.h>
-#include "lz4defs.h"
-
-/*
- * no public solution to solve our requirement yet.
- * see: <required buffer size for LZ4_decompress_safe_partial>
- *      https://groups.google.com/forum/#!topic/lz4c/_3kkz5N6n00
- */
-static FORCE_INLINE int customized_lz4_decompress_safe_partial(
-	const void * const source,
-	void * const dest,
-	int inputSize,
-	int outputSize)
-{
-	/* Local Variables */
-	const BYTE *ip = (const BYTE *) source;
-	const BYTE * const iend = ip + inputSize;
-
-	BYTE *op = (BYTE *) dest;
-	BYTE * const oend = op + outputSize;
-	BYTE *cpy;
-
-	static const unsigned int dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 };
-	static const int dec64table[] = { 0, 0, 0, -1, 0, 1, 2, 3 };
-
-	/* Empty output buffer */
-	if (unlikely(outputSize == 0))
-		return ((inputSize == 1) && (*ip == 0)) ? 0 : -1;
-
-	/* Main Loop : decode sequences */
-	while (1) {
-		size_t length;
-		const BYTE *match;
-		size_t offset;
-
-		/* get literal length */
-		unsigned int const token = *ip++;
-
-		length = token>>ML_BITS;
-
-		if (length == RUN_MASK) {
-			unsigned int s;
-
-			do {
-				s = *ip++;
-				length += s;
-			} while ((ip < iend - RUN_MASK) & (s == 255));
-
-			if (unlikely((size_t)(op + length) < (size_t)(op))) {
-				/* overflow detection */
-				goto _output_error;
-			}
-			if (unlikely((size_t)(ip + length) < (size_t)(ip))) {
-				/* overflow detection */
-				goto _output_error;
-			}
-		}
-
-		/* copy literals */
-		cpy = op + length;
-		if ((cpy > oend - WILDCOPYLENGTH) ||
-			(ip + length > iend - (2 + 1 + LASTLITERALS))) {
-			if (cpy > oend) {
-				memcpy(op, ip, length = oend - op);
-				op += length;
-				break;
-			}
-
-			if (unlikely(ip + length > iend)) {
-				/*
-				 * Error :
-				 * read attempt beyond
-				 * end of input buffer
-				 */
-				goto _output_error;
-			}
-
-			memcpy(op, ip, length);
-			ip += length;
-			op += length;
-
-			if (ip > iend - 2)
-				break;
-			/* Necessarily EOF, due to parsing restrictions */
-			/* break; */
-		} else {
-			LZ4_wildCopy(op, ip, cpy);
-			ip += length;
-			op = cpy;
-		}
-
-		/* get offset */
-		offset = LZ4_readLE16(ip);
-		ip += 2;
-		match = op - offset;
-
-		if (unlikely(match < (const BYTE *)dest)) {
-			/* Error : offset outside buffers */
-			goto _output_error;
-		}
-
-		/* get matchlength */
-		length = token & ML_MASK;
-		if (length == ML_MASK) {
-			unsigned int s;
-
-			do {
-				s = *ip++;
-
-				if (ip > iend - LASTLITERALS)
-					goto _output_error;
-
-				length += s;
-			} while (s == 255);
-
-			if (unlikely((size_t)(op + length) < (size_t)op)) {
-				/* overflow detection */
-				goto _output_error;
-			}
-		}
-
-		length += MINMATCH;
-
-		/* copy match within block */
-		cpy = op + length;
-
-		if (unlikely(cpy >= oend - WILDCOPYLENGTH)) {
-			if (cpy >= oend) {
-				while (op < oend)
-					*op++ = *match++;
-				break;
-			}
-			goto __match;
-		}
-
-		/* costs ~1%; silence an msan warning when offset == 0 */
-		LZ4_write32(op, (U32)offset);
-
-		if (unlikely(offset < 8)) {
-			const int dec64 = dec64table[offset];
-
-			op[0] = match[0];
-			op[1] = match[1];
-			op[2] = match[2];
-			op[3] = match[3];
-			match += dec32table[offset];
-			memcpy(op + 4, match, 4);
-			match -= dec64;
-		} else {
-			LZ4_copy8(op, match);
-			match += 8;
-		}
-
-		op += 8;
-
-		if (unlikely(cpy > oend - 12)) {
-			BYTE * const oCopyLimit = oend - (WILDCOPYLENGTH - 1);
-
-			if (op < oCopyLimit) {
-				LZ4_wildCopy(op, match, oCopyLimit);
-				match += oCopyLimit - op;
-				op = oCopyLimit;
-			}
-__match:
-			while (op < cpy)
-				*op++ = *match++;
-		} else {
-			LZ4_copy8(op, match);
-
-			if (length > 16)
-				LZ4_wildCopy(op + 8, match + 8, cpy);
-		}
-
-		op = cpy; /* correction */
-	}
-	DBG_BUGON((void *)ip - source > inputSize);
-	DBG_BUGON((void *)op - dest > outputSize);
-
-	/* Nb of output bytes decoded */
-	return (int) ((void *)op - dest);
-
-	/* Overflow error detected */
-_output_error:
-	return -ERANGE;
-}
-
-int z_erofs_unzip_lz4(void *in, void *out, size_t inlen, size_t outlen)
-{
-	int ret = customized_lz4_decompress_safe_partial(in,
-		out, inlen, outlen);
-
-	if (ret >= 0)
-		return ret;
-
-	/*
-	 * LZ4_decompress_safe will return an error code
-	 * (< 0) if decompression failed
-	 */
-	errln("%s, failed to decompress, in[%p, %zu] outlen[%p, %zu]",
-	      __func__, in, inlen, out, outlen);
-	WARN_ON(1);
-	print_hex_dump(KERN_DEBUG, "raw data [in]: ", DUMP_PREFIX_OFFSET,
-		16, 1, in, inlen, true);
-	print_hex_dump(KERN_DEBUG, "raw data [out]: ", DUMP_PREFIX_OFFSET,
-		16, 1, out, outlen, true);
-	return -EIO;
-}
-
diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
deleted file mode 100644
index 0f1558c6747e..000000000000
--- a/drivers/staging/erofs/unzip_vle.c
+++ /dev/null
@@ -1,1695 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * linux/drivers/staging/erofs/unzip_vle.c
- *
- * Copyright (C) 2018 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
- */
-#include "unzip_vle.h"
-#include <linux/prefetch.h>
-
-static struct workqueue_struct *z_erofs_workqueue __read_mostly;
-static struct kmem_cache *z_erofs_workgroup_cachep __read_mostly;
-
-void z_erofs_exit_zip_subsystem(void)
-{
-	destroy_workqueue(z_erofs_workqueue);
-	kmem_cache_destroy(z_erofs_workgroup_cachep);
-}
-
-static inline int init_unzip_workqueue(void)
-{
-	const unsigned onlinecpus = num_possible_cpus();
-
-	/*
-	 * we don't need too many threads, limiting threads
-	 * could improve scheduling performance.
-	 */
-	z_erofs_workqueue = alloc_workqueue("erofs_unzipd",
-		WQ_UNBOUND | WQ_HIGHPRI | WQ_CPU_INTENSIVE,
-		onlinecpus + onlinecpus / 4);
-
-	return z_erofs_workqueue != NULL ? 0 : -ENOMEM;
-}
-
-int z_erofs_init_zip_subsystem(void)
-{
-	z_erofs_workgroup_cachep =
-		kmem_cache_create("erofs_compress",
-		Z_EROFS_WORKGROUP_SIZE, 0,
-		SLAB_RECLAIM_ACCOUNT, NULL);
-
-	if (z_erofs_workgroup_cachep != NULL) {
-		if (!init_unzip_workqueue())
-			return 0;
-
-		kmem_cache_destroy(z_erofs_workgroup_cachep);
-	}
-	return -ENOMEM;
-}
-
-enum z_erofs_vle_work_role {
-	Z_EROFS_VLE_WORK_SECONDARY,
-	Z_EROFS_VLE_WORK_PRIMARY,
-	/*
-	 * The current work was the tail of an exist chain, and the previous
-	 * processed chained works are all decided to be hooked up to it.
-	 * A new chain should be created for the remaining unprocessed works,
-	 * therefore different from Z_EROFS_VLE_WORK_PRIMARY_FOLLOWED,
-	 * the next work cannot reuse the whole page in the following scenario:
-	 *  ________________________________________________________________
-	 * |      tail (partial) page     |       head (partial) page       |
-	 * |  (belongs to the next work)  |  (belongs to the current work)  |
-	 * |_______PRIMARY_FOLLOWED_______|________PRIMARY_HOOKED___________|
-	 */
-	Z_EROFS_VLE_WORK_PRIMARY_HOOKED,
-	/*
-	 * The current work has been linked with the processed chained works,
-	 * and could be also linked with the potential remaining works, which
-	 * means if the processing page is the tail partial page of the work,
-	 * the current work can safely use the whole page (since the next work
-	 * is under control) for in-place decompression, as illustrated below:
-	 *  ________________________________________________________________
-	 * |  tail (partial) page  |          head (partial) page           |
-	 * | (of the current work) |         (of the previous work)         |
-	 * |  PRIMARY_FOLLOWED or  |                                        |
-	 * |_____PRIMARY_HOOKED____|____________PRIMARY_FOLLOWED____________|
-	 *
-	 * [  (*) the above page can be used for the current work itself.  ]
-	 */
-	Z_EROFS_VLE_WORK_PRIMARY_FOLLOWED,
-	Z_EROFS_VLE_WORK_MAX
-};
-
-struct z_erofs_vle_work_builder {
-	enum z_erofs_vle_work_role role;
-	/*
-	 * 'hosted = false' means that the current workgroup doesn't belong to
-	 * the owned chained workgroups. In the other words, it is none of our
-	 * business to submit this workgroup.
-	 */
-	bool hosted;
-
-	struct z_erofs_vle_workgroup *grp;
-	struct z_erofs_vle_work *work;
-	struct z_erofs_pagevec_ctor vector;
-
-	/* pages used for reading the compressed data */
-	struct page **compressed_pages;
-	unsigned compressed_deficit;
-};
-
-#define VLE_WORK_BUILDER_INIT()	\
-	{ .work = NULL, .role = Z_EROFS_VLE_WORK_PRIMARY_FOLLOWED }
-
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-
-static bool grab_managed_cache_pages(struct address_space *mapping,
-				     erofs_blk_t start,
-				     struct page **compressed_pages,
-				     int clusterblks,
-				     bool reserve_allocation)
-{
-	bool noio = true;
-	unsigned int i;
-
-	/* TODO: optimize by introducing find_get_pages_range */
-	for (i = 0; i < clusterblks; ++i) {
-		struct page *page, *found;
-
-		if (READ_ONCE(compressed_pages[i]) != NULL)
-			continue;
-
-		page = found = find_get_page(mapping, start + i);
-		if (found == NULL) {
-			noio = false;
-			if (!reserve_allocation)
-				continue;
-			page = EROFS_UNALLOCATED_CACHED_PAGE;
-		}
-
-		if (NULL == cmpxchg(compressed_pages + i, NULL, page))
-			continue;
-
-		if (found != NULL)
-			put_page(found);
-	}
-	return noio;
-}
-
-/* called by erofs_shrinker to get rid of all compressed_pages */
-int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
-				       struct erofs_workgroup *egrp)
-{
-	struct z_erofs_vle_workgroup *const grp =
-		container_of(egrp, struct z_erofs_vle_workgroup, obj);
-	struct address_space *const mapping = sbi->managed_cache->i_mapping;
-	const int clusterpages = erofs_clusterpages(sbi);
-	int i;
-
-	/*
-	 * refcount of workgroup is now freezed as 1,
-	 * therefore no need to worry about available decompression users.
-	 */
-	for (i = 0; i < clusterpages; ++i) {
-		struct page *page = grp->compressed_pages[i];
-
-		if (page == NULL || page->mapping != mapping)
-			continue;
-
-		/* block other users from reclaiming or migrating the page */
-		if (!trylock_page(page))
-			return -EBUSY;
-
-		/* barrier is implied in the following 'unlock_page' */
-		WRITE_ONCE(grp->compressed_pages[i], NULL);
-
-		set_page_private(page, 0);
-		ClearPagePrivate(page);
-
-		unlock_page(page);
-		put_page(page);
-	}
-	return 0;
-}
-
-int erofs_try_to_free_cached_page(struct address_space *mapping,
-				  struct page *page)
-{
-	struct erofs_sb_info *const sbi = EROFS_SB(mapping->host->i_sb);
-	const unsigned int clusterpages = erofs_clusterpages(sbi);
-
-	struct z_erofs_vle_workgroup *grp;
-	int ret = 0;	/* 0 - busy */
-
-	/* prevent the workgroup from being freed */
-	rcu_read_lock();
-	grp = (void *)page_private(page);
-
-	if (erofs_workgroup_try_to_freeze(&grp->obj, 1)) {
-		unsigned int i;
-
-		for (i = 0; i < clusterpages; ++i) {
-			if (grp->compressed_pages[i] == page) {
-				WRITE_ONCE(grp->compressed_pages[i], NULL);
-				ret = 1;
-				break;
-			}
-		}
-		erofs_workgroup_unfreeze(&grp->obj, 1);
-	}
-	rcu_read_unlock();
-
-	if (ret) {
-		ClearPagePrivate(page);
-		put_page(page);
-	}
-	return ret;
-}
-#endif
-
-/* page_type must be Z_EROFS_PAGE_TYPE_EXCLUSIVE */
-static inline bool try_to_reuse_as_compressed_page(
-	struct z_erofs_vle_work_builder *b,
-	struct page *page)
-{
-	while (b->compressed_deficit) {
-		--b->compressed_deficit;
-		if (NULL == cmpxchg(b->compressed_pages++, NULL, page))
-			return true;
-	}
-
-	return false;
-}
-
-/* callers must be with work->lock held */
-static int z_erofs_vle_work_add_page(
-	struct z_erofs_vle_work_builder *builder,
-	struct page *page,
-	enum z_erofs_page_type type)
-{
-	int ret;
-	bool occupied;
-
-	/* give priority for the compressed data storage */
-	if (builder->role >= Z_EROFS_VLE_WORK_PRIMARY &&
-		type == Z_EROFS_PAGE_TYPE_EXCLUSIVE &&
-		try_to_reuse_as_compressed_page(builder, page))
-		return 0;
-
-	ret = z_erofs_pagevec_ctor_enqueue(&builder->vector,
-		page, type, &occupied);
-	builder->work->vcnt += (unsigned)ret;
-
-	return ret ? 0 : -EAGAIN;
-}
-
-static enum z_erofs_vle_work_role
-try_to_claim_workgroup(struct z_erofs_vle_workgroup *grp,
-		       z_erofs_vle_owned_workgrp_t *owned_head,
-		       bool *hosted)
-{
-	DBG_BUGON(*hosted == true);
-
-	/* let's claim these following types of workgroup */
-retry:
-	if (grp->next == Z_EROFS_VLE_WORKGRP_NIL) {
-		/* type 1, nil workgroup */
-		if (Z_EROFS_VLE_WORKGRP_NIL != cmpxchg(&grp->next,
-			Z_EROFS_VLE_WORKGRP_NIL, *owned_head))
-			goto retry;
-
-		*owned_head = grp;
-		*hosted = true;
-		/* lucky, I am the followee :) */
-		return Z_EROFS_VLE_WORK_PRIMARY_FOLLOWED;
-
-	} else if (grp->next == Z_EROFS_VLE_WORKGRP_TAIL) {
-		/*
-		 * type 2, link to the end of a existing open chain,
-		 * be careful that its submission itself is governed
-		 * by the original owned chain.
-		 */
-		if (Z_EROFS_VLE_WORKGRP_TAIL != cmpxchg(&grp->next,
-			Z_EROFS_VLE_WORKGRP_TAIL, *owned_head))
-			goto retry;
-		*owned_head = Z_EROFS_VLE_WORKGRP_TAIL;
-		return Z_EROFS_VLE_WORK_PRIMARY_HOOKED;
-	}
-
-	return Z_EROFS_VLE_WORK_PRIMARY; /* :( better luck next time */
-}
-
-static struct z_erofs_vle_work *
-z_erofs_vle_work_lookup(struct super_block *sb,
-			pgoff_t idx, unsigned pageofs,
-			struct z_erofs_vle_workgroup **grp_ret,
-			enum z_erofs_vle_work_role *role,
-			z_erofs_vle_owned_workgrp_t *owned_head,
-			bool *hosted)
-{
-	bool tag, primary;
-	struct erofs_workgroup *egrp;
-	struct z_erofs_vle_workgroup *grp;
-	struct z_erofs_vle_work *work;
-
-	egrp = erofs_find_workgroup(sb, idx, &tag);
-	if (egrp == NULL) {
-		*grp_ret = NULL;
-		return NULL;
-	}
-
-	*grp_ret = grp = container_of(egrp,
-		struct z_erofs_vle_workgroup, obj);
-
-	work = z_erofs_vle_grab_work(grp, pageofs);
-	/* if multiref is disabled, `primary' is always true */
-	primary = true;
-
-	if (work->pageofs != pageofs) {
-		DBG_BUGON(1);
-		erofs_workgroup_put(egrp);
-		return ERR_PTR(-EIO);
-	}
-
-	/*
-	 * lock must be taken first to avoid grp->next == NIL between
-	 * claiming workgroup and adding pages:
-	 *                        grp->next != NIL
-	 *   grp->next = NIL
-	 *   mutex_unlock_all
-	 *                        mutex_lock(&work->lock)
-	 *                        add all pages to pagevec
-	 *
-	 * [correct locking case 1]:
-	 *   mutex_lock(grp->work[a])
-	 *   ...
-	 *   mutex_lock(grp->work[b])     mutex_lock(grp->work[c])
-	 *   ...                          *role = SECONDARY
-	 *                                add all pages to pagevec
-	 *                                ...
-	 *                                mutex_unlock(grp->work[c])
-	 *   mutex_lock(grp->work[c])
-	 *   ...
-	 *   grp->next = NIL
-	 *   mutex_unlock_all
-	 *
-	 * [correct locking case 2]:
-	 *   mutex_lock(grp->work[b])
-	 *   ...
-	 *   mutex_lock(grp->work[a])
-	 *   ...
-	 *   mutex_lock(grp->work[c])
-	 *   ...
-	 *   grp->next = NIL
-	 *   mutex_unlock_all
-	 *                                mutex_lock(grp->work[a])
-	 *                                *role = PRIMARY_OWNER
-	 *                                add all pages to pagevec
-	 *                                ...
-	 */
-	mutex_lock(&work->lock);
-
-	*hosted = false;
-	if (!primary)
-		*role = Z_EROFS_VLE_WORK_SECONDARY;
-	else	/* claim the workgroup if possible */
-		*role = try_to_claim_workgroup(grp, owned_head, hosted);
-	return work;
-}
-
-static struct z_erofs_vle_work *
-z_erofs_vle_work_register(struct super_block *sb,
-			  struct z_erofs_vle_workgroup **grp_ret,
-			  struct erofs_map_blocks *map,
-			  pgoff_t index, unsigned pageofs,
-			  enum z_erofs_vle_work_role *role,
-			  z_erofs_vle_owned_workgrp_t *owned_head,
-			  bool *hosted)
-{
-	bool newgrp = false;
-	struct z_erofs_vle_workgroup *grp = *grp_ret;
-	struct z_erofs_vle_work *work;
-
-	/* if multiref is disabled, grp should never be nullptr */
-	if (unlikely(grp)) {
-		DBG_BUGON(1);
-		return ERR_PTR(-EINVAL);
-	}
-
-	/* no available workgroup, let's allocate one */
-	grp = kmem_cache_zalloc(z_erofs_workgroup_cachep, GFP_NOFS);
-	if (unlikely(grp == NULL))
-		return ERR_PTR(-ENOMEM);
-
-	grp->obj.index = index;
-	grp->llen = map->m_llen;
-
-	z_erofs_vle_set_workgrp_fmt(grp,
-		(map->m_flags & EROFS_MAP_ZIPPED) ?
-			Z_EROFS_VLE_WORKGRP_FMT_LZ4 :
-			Z_EROFS_VLE_WORKGRP_FMT_PLAIN);
-	atomic_set(&grp->obj.refcount, 1);
-
-	/* new workgrps have been claimed as type 1 */
-	WRITE_ONCE(grp->next, *owned_head);
-	/* primary and followed work for all new workgrps */
-	*role = Z_EROFS_VLE_WORK_PRIMARY_FOLLOWED;
-	/* it should be submitted by ourselves */
-	*hosted = true;
-
-	newgrp = true;
-	work = z_erofs_vle_grab_primary_work(grp);
-	work->pageofs = pageofs;
-
-	mutex_init(&work->lock);
-
-	if (newgrp) {
-		int err = erofs_register_workgroup(sb, &grp->obj, 0);
-
-		if (err) {
-			kmem_cache_free(z_erofs_workgroup_cachep, grp);
-			return ERR_PTR(-EAGAIN);
-		}
-	}
-
-	*owned_head = *grp_ret = grp;
-
-	mutex_lock(&work->lock);
-	return work;
-}
-
-static inline void __update_workgrp_llen(struct z_erofs_vle_workgroup *grp,
-					 unsigned int llen)
-{
-	while (1) {
-		unsigned int orig_llen = grp->llen;
-
-		if (orig_llen >= llen || orig_llen ==
-			cmpxchg(&grp->llen, orig_llen, llen))
-			break;
-	}
-}
-
-#define builder_is_hooked(builder) \
-	((builder)->role >= Z_EROFS_VLE_WORK_PRIMARY_HOOKED)
-
-#define builder_is_followed(builder) \
-	((builder)->role >= Z_EROFS_VLE_WORK_PRIMARY_FOLLOWED)
-
-static int z_erofs_vle_work_iter_begin(struct z_erofs_vle_work_builder *builder,
-				       struct super_block *sb,
-				       struct erofs_map_blocks *map,
-				       z_erofs_vle_owned_workgrp_t *owned_head)
-{
-	const unsigned clusterpages = erofs_clusterpages(EROFS_SB(sb));
-	const erofs_blk_t index = erofs_blknr(map->m_pa);
-	const unsigned pageofs = map->m_la & ~PAGE_MASK;
-	struct z_erofs_vle_workgroup *grp;
-	struct z_erofs_vle_work *work;
-
-	DBG_BUGON(builder->work != NULL);
-
-	/* must be Z_EROFS_WORK_TAIL or the next chained work */
-	DBG_BUGON(*owned_head == Z_EROFS_VLE_WORKGRP_NIL);
-	DBG_BUGON(*owned_head == Z_EROFS_VLE_WORKGRP_TAIL_CLOSED);
-
-	DBG_BUGON(erofs_blkoff(map->m_pa));
-
-repeat:
-	work = z_erofs_vle_work_lookup(sb, index,
-		pageofs, &grp, &builder->role, owned_head, &builder->hosted);
-	if (work != NULL) {
-		__update_workgrp_llen(grp, map->m_llen);
-		goto got_it;
-	}
-
-	work = z_erofs_vle_work_register(sb, &grp, map, index, pageofs,
-		&builder->role, owned_head, &builder->hosted);
-
-	if (unlikely(work == ERR_PTR(-EAGAIN)))
-		goto repeat;
-
-	if (unlikely(IS_ERR(work)))
-		return PTR_ERR(work);
-got_it:
-	z_erofs_pagevec_ctor_init(&builder->vector,
-		Z_EROFS_VLE_INLINE_PAGEVECS, work->pagevec, work->vcnt);
-
-	if (builder->role >= Z_EROFS_VLE_WORK_PRIMARY) {
-		/* enable possibly in-place decompression */
-		builder->compressed_pages = grp->compressed_pages;
-		builder->compressed_deficit = clusterpages;
-	} else {
-		builder->compressed_pages = NULL;
-		builder->compressed_deficit = 0;
-	}
-
-	builder->grp = grp;
-	builder->work = work;
-	return 0;
-}
-
-/*
- * keep in mind that no referenced workgroups will be freed
- * only after a RCU grace period, so rcu_read_lock() could
- * prevent a workgroup from being freed.
- */
-static void z_erofs_rcu_callback(struct rcu_head *head)
-{
-	struct z_erofs_vle_work *work =	container_of(head,
-		struct z_erofs_vle_work, rcu);
-	struct z_erofs_vle_workgroup *grp =
-		z_erofs_vle_work_workgroup(work, true);
-
-	kmem_cache_free(z_erofs_workgroup_cachep, grp);
-}
-
-void erofs_workgroup_free_rcu(struct erofs_workgroup *grp)
-{
-	struct z_erofs_vle_workgroup *const vgrp = container_of(grp,
-		struct z_erofs_vle_workgroup, obj);
-	struct z_erofs_vle_work *const work = &vgrp->work;
-
-	call_rcu(&work->rcu, z_erofs_rcu_callback);
-}
-
-static void __z_erofs_vle_work_release(struct z_erofs_vle_workgroup *grp,
-	struct z_erofs_vle_work *work __maybe_unused)
-{
-	erofs_workgroup_put(&grp->obj);
-}
-
-void z_erofs_vle_work_release(struct z_erofs_vle_work *work)
-{
-	struct z_erofs_vle_workgroup *grp =
-		z_erofs_vle_work_workgroup(work, true);
-
-	__z_erofs_vle_work_release(grp, work);
-}
-
-static inline bool
-z_erofs_vle_work_iter_end(struct z_erofs_vle_work_builder *builder)
-{
-	struct z_erofs_vle_work *work = builder->work;
-
-	if (work == NULL)
-		return false;
-
-	z_erofs_pagevec_ctor_exit(&builder->vector, false);
-	mutex_unlock(&work->lock);
-
-	/*
-	 * if all pending pages are added, don't hold work reference
-	 * any longer if the current work isn't hosted by ourselves.
-	 */
-	if (!builder->hosted)
-		__z_erofs_vle_work_release(builder->grp, work);
-
-	builder->work = NULL;
-	builder->grp = NULL;
-	return true;
-}
-
-static inline struct page *__stagingpage_alloc(struct list_head *pagepool,
-					       gfp_t gfp)
-{
-	struct page *page = erofs_allocpage(pagepool, gfp);
-
-	if (unlikely(page == NULL))
-		return NULL;
-
-	page->mapping = Z_EROFS_MAPPING_STAGING;
-	return page;
-}
-
-struct z_erofs_vle_frontend {
-	struct inode *const inode;
-
-	struct z_erofs_vle_work_builder builder;
-	struct erofs_map_blocks_iter m_iter;
-
-	z_erofs_vle_owned_workgrp_t owned_head;
-
-	bool initial;
-#if (EROFS_FS_ZIP_CACHE_LVL >= 2)
-	erofs_off_t cachedzone_la;
-#endif
-};
-
-#define VLE_FRONTEND_INIT(__i) { \
-	.inode = __i, \
-	.m_iter = { \
-		{ .m_llen = 0, .m_plen = 0 }, \
-		.mpage = NULL \
-	}, \
-	.builder = VLE_WORK_BUILDER_INIT(), \
-	.owned_head = Z_EROFS_VLE_WORKGRP_TAIL, \
-	.initial = true, }
-
-static int z_erofs_do_read_page(struct z_erofs_vle_frontend *fe,
-				struct page *page,
-				struct list_head *page_pool)
-{
-	struct super_block *const sb = fe->inode->i_sb;
-	struct erofs_sb_info *const sbi __maybe_unused = EROFS_SB(sb);
-	struct erofs_map_blocks_iter *const m = &fe->m_iter;
-	struct erofs_map_blocks *const map = &m->map;
-	struct z_erofs_vle_work_builder *const builder = &fe->builder;
-	const loff_t offset = page_offset(page);
-
-	bool tight = builder_is_hooked(builder);
-	struct z_erofs_vle_work *work = builder->work;
-
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-	struct address_space *const mngda = sbi->managed_cache->i_mapping;
-	struct z_erofs_vle_workgroup *grp;
-	bool noio_outoforder;
-#endif
-
-	enum z_erofs_page_type page_type;
-	unsigned cur, end, spiltted, index;
-	int err = 0;
-
-	/* register locked file pages as online pages in pack */
-	z_erofs_onlinepage_init(page);
-
-	spiltted = 0;
-	end = PAGE_SIZE;
-repeat:
-	cur = end - 1;
-
-	/* lucky, within the range of the current map_blocks */
-	if (offset + cur >= map->m_la &&
-		offset + cur < map->m_la + map->m_llen) {
-		/* didn't get a valid unzip work previously (very rare) */
-		if (!builder->work)
-			goto restart_now;
-		goto hitted;
-	}
-
-	/* go ahead the next map_blocks */
-	debugln("%s: [out-of-range] pos %llu", __func__, offset + cur);
-
-	if (z_erofs_vle_work_iter_end(builder))
-		fe->initial = false;
-
-	map->m_la = offset + cur;
-	map->m_llen = 0;
-	err = erofs_map_blocks_iter(fe->inode, map, &m->mpage, 0);
-	if (unlikely(err))
-		goto err_out;
-
-restart_now:
-	if (unlikely(!(map->m_flags & EROFS_MAP_MAPPED)))
-		goto hitted;
-
-	DBG_BUGON(map->m_plen != 1 << sbi->clusterbits);
-	DBG_BUGON(erofs_blkoff(map->m_pa));
-
-	err = z_erofs_vle_work_iter_begin(builder, sb, map, &fe->owned_head);
-	if (unlikely(err))
-		goto err_out;
-
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-	grp = fe->builder.grp;
-
-	/* let's do out-of-order decompression for noio */
-	noio_outoforder = grab_managed_cache_pages(mngda,
-		erofs_blknr(map->m_pa),
-		grp->compressed_pages, erofs_blknr(map->m_plen),
-		/* compressed page caching selection strategy */
-		fe->initial | (EROFS_FS_ZIP_CACHE_LVL >= 2 ?
-			map->m_la < fe->cachedzone_la : 0));
-
-	if (noio_outoforder && builder_is_followed(builder))
-		builder->role = Z_EROFS_VLE_WORK_PRIMARY;
-#endif
-
-	tight &= builder_is_hooked(builder);
-	work = builder->work;
-hitted:
-	cur = end - min_t(unsigned, offset + end - map->m_la, end);
-	if (unlikely(!(map->m_flags & EROFS_MAP_MAPPED))) {
-		zero_user_segment(page, cur, end);
-		goto next_part;
-	}
-
-	/* let's derive page type */
-	page_type = cur ? Z_EROFS_VLE_PAGE_TYPE_HEAD :
-		(!spiltted ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
-			(tight ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
-				Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED));
-
-	if (cur)
-		tight &= builder_is_followed(builder);
-
-retry:
-	err = z_erofs_vle_work_add_page(builder, page, page_type);
-	/* should allocate an additional staging page for pagevec */
-	if (err == -EAGAIN) {
-		struct page *const newpage =
-			__stagingpage_alloc(page_pool, GFP_NOFS);
-
-		err = z_erofs_vle_work_add_page(builder,
-			newpage, Z_EROFS_PAGE_TYPE_EXCLUSIVE);
-		if (likely(!err))
-			goto retry;
-	}
-
-	if (unlikely(err))
-		goto err_out;
-
-	index = page->index - map->m_la / PAGE_SIZE;
-
-	/* FIXME! avoid the last relundant fixup & endio */
-	z_erofs_onlinepage_fixup(page, index, true);
-
-	/* bump up the number of spiltted parts of a page */
-	++spiltted;
-	/* also update nr_pages */
-	work->nr_pages = max_t(pgoff_t, work->nr_pages, index + 1);
-next_part:
-	/* can be used for verification */
-	map->m_llen = offset + cur - map->m_la;
-
-	end = cur;
-	if (end > 0)
-		goto repeat;
-
-out:
-	/* FIXME! avoid the last relundant fixup & endio */
-	z_erofs_onlinepage_endio(page);
-
-	debugln("%s, finish page: %pK spiltted: %u map->m_llen %llu",
-		__func__, page, spiltted, map->m_llen);
-	return err;
-
-	/* if some error occurred while processing this page */
-err_out:
-	SetPageError(page);
-	goto out;
-}
-
-static void z_erofs_vle_unzip_kickoff(void *ptr, int bios)
-{
-	tagptr1_t t = tagptr_init(tagptr1_t, ptr);
-	struct z_erofs_vle_unzip_io *io = tagptr_unfold_ptr(t);
-	bool background = tagptr_unfold_tags(t);
-
-	if (!background) {
-		unsigned long flags;
-
-		spin_lock_irqsave(&io->u.wait.lock, flags);
-		if (!atomic_add_return(bios, &io->pending_bios))
-			wake_up_locked(&io->u.wait);
-		spin_unlock_irqrestore(&io->u.wait.lock, flags);
-		return;
-	}
-
-	if (!atomic_add_return(bios, &io->pending_bios))
-		queue_work(z_erofs_workqueue, &io->u.work);
-}
-
-static inline void z_erofs_vle_read_endio(struct bio *bio)
-{
-	const blk_status_t err = bio->bi_status;
-	unsigned i;
-	struct bio_vec *bvec;
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-	struct address_space *mngda = NULL;
-#endif
-
-	bio_for_each_segment_all(bvec, bio, i) {
-		struct page *page = bvec->bv_page;
-		bool cachemngd = false;
-
-		DBG_BUGON(PageUptodate(page));
-		DBG_BUGON(!page->mapping);
-
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-		if (unlikely(mngda == NULL && !z_erofs_is_stagingpage(page))) {
-			struct inode *const inode = page->mapping->host;
-			struct super_block *const sb = inode->i_sb;
-
-			mngda = EROFS_SB(sb)->managed_cache->i_mapping;
-		}
-
-		/*
-		 * If mngda has not gotten, it equals NULL,
-		 * however, page->mapping never be NULL if working properly.
-		 */
-		cachemngd = (page->mapping == mngda);
-#endif
-
-		if (unlikely(err))
-			SetPageError(page);
-		else if (cachemngd)
-			SetPageUptodate(page);
-
-		if (cachemngd)
-			unlock_page(page);
-	}
-
-	z_erofs_vle_unzip_kickoff(bio->bi_private, -1);
-	bio_put(bio);
-}
-
-static struct page *z_pagemap_global[Z_EROFS_VLE_VMAP_GLOBAL_PAGES];
-static DEFINE_MUTEX(z_pagemap_global_lock);
-
-static int z_erofs_vle_unzip(struct super_block *sb,
-	struct z_erofs_vle_workgroup *grp,
-	struct list_head *page_pool)
-{
-	struct erofs_sb_info *const sbi = EROFS_SB(sb);
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-	struct address_space *const mngda = sbi->managed_cache->i_mapping;
-#endif
-	const unsigned clusterpages = erofs_clusterpages(sbi);
-
-	struct z_erofs_pagevec_ctor ctor;
-	unsigned int nr_pages;
-	unsigned int sparsemem_pages = 0;
-	struct page *pages_onstack[Z_EROFS_VLE_VMAP_ONSTACK_PAGES];
-	struct page **pages, **compressed_pages, *page;
-	unsigned i, llen;
-
-	enum z_erofs_page_type page_type;
-	bool overlapped;
-	struct z_erofs_vle_work *work;
-	void *vout;
-	int err;
-
-	might_sleep();
-	work = z_erofs_vle_grab_primary_work(grp);
-	DBG_BUGON(!READ_ONCE(work->nr_pages));
-
-	mutex_lock(&work->lock);
-	nr_pages = work->nr_pages;
-
-	if (likely(nr_pages <= Z_EROFS_VLE_VMAP_ONSTACK_PAGES))
-		pages = pages_onstack;
-	else if (nr_pages <= Z_EROFS_VLE_VMAP_GLOBAL_PAGES &&
-		mutex_trylock(&z_pagemap_global_lock))
-		pages = z_pagemap_global;
-	else {
-repeat:
-		pages = kvmalloc_array(nr_pages,
-			sizeof(struct page *), GFP_KERNEL);
-
-		/* fallback to global pagemap for the lowmem scenario */
-		if (unlikely(pages == NULL)) {
-			if (nr_pages > Z_EROFS_VLE_VMAP_GLOBAL_PAGES)
-				goto repeat;
-			else {
-				mutex_lock(&z_pagemap_global_lock);
-				pages = z_pagemap_global;
-			}
-		}
-	}
-
-	for (i = 0; i < nr_pages; ++i)
-		pages[i] = NULL;
-
-	err = 0;
-	z_erofs_pagevec_ctor_init(&ctor,
-		Z_EROFS_VLE_INLINE_PAGEVECS, work->pagevec, 0);
-
-	for (i = 0; i < work->vcnt; ++i) {
-		unsigned pagenr;
-
-		page = z_erofs_pagevec_ctor_dequeue(&ctor, &page_type);
-
-		/* all pages in pagevec ought to be valid */
-		DBG_BUGON(page == NULL);
-		DBG_BUGON(page->mapping == NULL);
-
-		if (z_erofs_gather_if_stagingpage(page_pool, page))
-			continue;
-
-		if (page_type == Z_EROFS_VLE_PAGE_TYPE_HEAD)
-			pagenr = 0;
-		else
-			pagenr = z_erofs_onlinepage_index(page);
-
-		DBG_BUGON(pagenr >= nr_pages);
-
-		/*
-		 * currently EROFS doesn't support multiref(dedup),
-		 * so here erroring out one multiref page.
-		 */
-		if (pages[pagenr]) {
-			DBG_BUGON(1);
-			SetPageError(pages[pagenr]);
-			z_erofs_onlinepage_endio(pages[pagenr]);
-			err = -EIO;
-		}
-		pages[pagenr] = page;
-	}
-	sparsemem_pages = i;
-
-	z_erofs_pagevec_ctor_exit(&ctor, true);
-
-	overlapped = false;
-	compressed_pages = grp->compressed_pages;
-
-	for (i = 0; i < clusterpages; ++i) {
-		unsigned pagenr;
-
-		page = compressed_pages[i];
-
-		/* all compressed pages ought to be valid */
-		DBG_BUGON(page == NULL);
-		DBG_BUGON(page->mapping == NULL);
-
-		if (!z_erofs_is_stagingpage(page)) {
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-			if (page->mapping == mngda) {
-				if (unlikely(!PageUptodate(page)))
-					err = -EIO;
-				continue;
-			}
-#endif
-
-			/*
-			 * only if non-head page can be selected
-			 * for inplace decompression
-			 */
-			pagenr = z_erofs_onlinepage_index(page);
-
-			DBG_BUGON(pagenr >= nr_pages);
-			if (pages[pagenr]) {
-				DBG_BUGON(1);
-				SetPageError(pages[pagenr]);
-				z_erofs_onlinepage_endio(pages[pagenr]);
-				err = -EIO;
-			}
-			++sparsemem_pages;
-			pages[pagenr] = page;
-
-			overlapped = true;
-		}
-
-		/* PG_error needs checking for inplaced and staging pages */
-		if (unlikely(PageError(page))) {
-			DBG_BUGON(PageUptodate(page));
-			err = -EIO;
-		}
-	}
-
-	if (unlikely(err))
-		goto out;
-
-	llen = (nr_pages << PAGE_SHIFT) - work->pageofs;
-
-	if (z_erofs_vle_workgrp_fmt(grp) == Z_EROFS_VLE_WORKGRP_FMT_PLAIN) {
-		err = z_erofs_vle_plain_copy(compressed_pages, clusterpages,
-			pages, nr_pages, work->pageofs);
-		goto out;
-	}
-
-	if (llen > grp->llen)
-		llen = grp->llen;
-
-	err = z_erofs_vle_unzip_fast_percpu(compressed_pages, clusterpages,
-					    pages, llen, work->pageofs);
-	if (err != -ENOTSUPP)
-		goto out;
-
-	if (sparsemem_pages >= nr_pages)
-		goto skip_allocpage;
-
-	for (i = 0; i < nr_pages; ++i) {
-		if (pages[i] != NULL)
-			continue;
-
-		pages[i] = __stagingpage_alloc(page_pool, GFP_NOFS);
-	}
-
-skip_allocpage:
-	vout = erofs_vmap(pages, nr_pages);
-	if (!vout) {
-		err = -ENOMEM;
-		goto out;
-	}
-
-	err = z_erofs_vle_unzip_vmap(compressed_pages,
-		clusterpages, vout, llen, work->pageofs, overlapped);
-
-	erofs_vunmap(vout, nr_pages);
-
-out:
-	/* must handle all compressed pages before endding pages */
-	for (i = 0; i < clusterpages; ++i) {
-		page = compressed_pages[i];
-
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-		if (page->mapping == mngda)
-			continue;
-#endif
-		/* recycle all individual staging pages */
-		(void)z_erofs_gather_if_stagingpage(page_pool, page);
-
-		WRITE_ONCE(compressed_pages[i], NULL);
-	}
-
-	for (i = 0; i < nr_pages; ++i) {
-		page = pages[i];
-		if (!page)
-			continue;
-
-		DBG_BUGON(page->mapping == NULL);
-
-		/* recycle all individual staging pages */
-		if (z_erofs_gather_if_stagingpage(page_pool, page))
-			continue;
-
-		if (unlikely(err < 0))
-			SetPageError(page);
-
-		z_erofs_onlinepage_endio(page);
-	}
-
-	if (pages == z_pagemap_global)
-		mutex_unlock(&z_pagemap_global_lock);
-	else if (unlikely(pages != pages_onstack))
-		kvfree(pages);
-
-	work->nr_pages = 0;
-	work->vcnt = 0;
-
-	/* all work locks MUST be taken before the following line */
-
-	WRITE_ONCE(grp->next, Z_EROFS_VLE_WORKGRP_NIL);
-
-	/* all work locks SHOULD be released right now */
-	mutex_unlock(&work->lock);
-
-	z_erofs_vle_work_release(work);
-	return err;
-}
-
-static void z_erofs_vle_unzip_all(struct super_block *sb,
-				  struct z_erofs_vle_unzip_io *io,
-				  struct list_head *page_pool)
-{
-	z_erofs_vle_owned_workgrp_t owned = io->head;
-
-	while (owned != Z_EROFS_VLE_WORKGRP_TAIL_CLOSED) {
-		struct z_erofs_vle_workgroup *grp;
-
-		/* no possible that 'owned' equals Z_EROFS_WORK_TPTR_TAIL */
-		DBG_BUGON(owned == Z_EROFS_VLE_WORKGRP_TAIL);
-
-		/* no possible that 'owned' equals NULL */
-		DBG_BUGON(owned == Z_EROFS_VLE_WORKGRP_NIL);
-
-		grp = owned;
-		owned = READ_ONCE(grp->next);
-
-		z_erofs_vle_unzip(sb, grp, page_pool);
-	}
-}
-
-static void z_erofs_vle_unzip_wq(struct work_struct *work)
-{
-	struct z_erofs_vle_unzip_io_sb *iosb = container_of(work,
-		struct z_erofs_vle_unzip_io_sb, io.u.work);
-	LIST_HEAD(page_pool);
-
-	DBG_BUGON(iosb->io.head == Z_EROFS_VLE_WORKGRP_TAIL_CLOSED);
-	z_erofs_vle_unzip_all(iosb->sb, &iosb->io, &page_pool);
-
-	put_pages_list(&page_pool);
-	kvfree(iosb);
-}
-
-static inline struct z_erofs_vle_unzip_io *
-prepare_io_handler(struct super_block *sb,
-		   struct z_erofs_vle_unzip_io *io,
-		   bool background)
-{
-	struct z_erofs_vle_unzip_io_sb *iosb;
-
-	if (!background) {
-		/* waitqueue available for foreground io */
-		BUG_ON(io == NULL);
-
-		init_waitqueue_head(&io->u.wait);
-		atomic_set(&io->pending_bios, 0);
-		goto out;
-	}
-
-	if (io != NULL)
-		BUG();
-	else {
-		/* allocate extra io descriptor for background io */
-		iosb = kvzalloc(sizeof(struct z_erofs_vle_unzip_io_sb),
-			GFP_KERNEL | __GFP_NOFAIL);
-		BUG_ON(iosb == NULL);
-
-		io = &iosb->io;
-	}
-
-	iosb->sb = sb;
-	INIT_WORK(&io->u.work, z_erofs_vle_unzip_wq);
-out:
-	io->head = Z_EROFS_VLE_WORKGRP_TAIL_CLOSED;
-	return io;
-}
-
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-/* true - unlocked (noio), false - locked (need submit io) */
-static inline bool recover_managed_page(struct z_erofs_vle_workgroup *grp,
-					struct page *page)
-{
-	wait_on_page_locked(page);
-	if (PagePrivate(page) && PageUptodate(page))
-		return true;
-
-	lock_page(page);
-	ClearPageError(page);
-
-	if (unlikely(!PagePrivate(page))) {
-		set_page_private(page, (unsigned long)grp);
-		SetPagePrivate(page);
-	}
-	if (unlikely(PageUptodate(page))) {
-		unlock_page(page);
-		return true;
-	}
-	return false;
-}
-
-#define __FSIO_1 1
-#else
-#define __FSIO_1 0
-#endif
-
-static bool z_erofs_vle_submit_all(struct super_block *sb,
-				   z_erofs_vle_owned_workgrp_t owned_head,
-				   struct list_head *pagepool,
-				   struct z_erofs_vle_unzip_io *fg_io,
-				   bool force_fg)
-{
-	struct erofs_sb_info *const sbi = EROFS_SB(sb);
-	const unsigned clusterpages = erofs_clusterpages(sbi);
-	const gfp_t gfp = GFP_NOFS;
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-	struct address_space *const mngda = sbi->managed_cache->i_mapping;
-	struct z_erofs_vle_workgroup *lstgrp_noio = NULL, *lstgrp_io = NULL;
-#endif
-	struct z_erofs_vle_unzip_io *ios[1 + __FSIO_1];
-	struct bio *bio;
-	tagptr1_t bi_private;
-	/* since bio will be NULL, no need to initialize last_index */
-	pgoff_t uninitialized_var(last_index);
-	bool force_submit = false;
-	unsigned nr_bios;
-
-	if (unlikely(owned_head == Z_EROFS_VLE_WORKGRP_TAIL))
-		return false;
-
-	/*
-	 * force_fg == 1, (io, fg_io[0]) no io, (io, fg_io[1]) need submit io
-	 * force_fg == 0, (io, fg_io[0]) no io; (io[1], bg_io) need submit io
-	 */
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-	ios[0] = prepare_io_handler(sb, fg_io + 0, false);
-#endif
-
-	if (force_fg) {
-		ios[__FSIO_1] = prepare_io_handler(sb, fg_io + __FSIO_1, false);
-		bi_private = tagptr_fold(tagptr1_t, ios[__FSIO_1], 0);
-	} else {
-		ios[__FSIO_1] = prepare_io_handler(sb, NULL, true);
-		bi_private = tagptr_fold(tagptr1_t, ios[__FSIO_1], 1);
-	}
-
-	nr_bios = 0;
-	force_submit = false;
-	bio = NULL;
-
-	/* by default, all need io submission */
-	ios[__FSIO_1]->head = owned_head;
-
-	do {
-		struct z_erofs_vle_workgroup *grp;
-		struct page **compressed_pages, *oldpage, *page;
-		pgoff_t first_index;
-		unsigned i = 0;
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-		unsigned int noio = 0;
-		bool cachemngd;
-#endif
-		int err;
-
-		/* no possible 'owned_head' equals the following */
-		DBG_BUGON(owned_head == Z_EROFS_VLE_WORKGRP_TAIL_CLOSED);
-		DBG_BUGON(owned_head == Z_EROFS_VLE_WORKGRP_NIL);
-
-		grp = owned_head;
-
-		/* close the main owned chain at first */
-		owned_head = cmpxchg(&grp->next, Z_EROFS_VLE_WORKGRP_TAIL,
-			Z_EROFS_VLE_WORKGRP_TAIL_CLOSED);
-
-		first_index = grp->obj.index;
-		compressed_pages = grp->compressed_pages;
-
-		force_submit |= (first_index != last_index + 1);
-repeat:
-		/* fulfill all compressed pages */
-		oldpage = page = READ_ONCE(compressed_pages[i]);
-
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-		cachemngd = false;
-
-		if (page == EROFS_UNALLOCATED_CACHED_PAGE) {
-			cachemngd = true;
-			goto do_allocpage;
-		} else if (page != NULL) {
-			if (page->mapping != mngda)
-				BUG_ON(PageUptodate(page));
-			else if (recover_managed_page(grp, page)) {
-				/* page is uptodate, skip io submission */
-				force_submit = true;
-				++noio;
-				goto skippage;
-			}
-		} else {
-do_allocpage:
-#else
-		if (page != NULL)
-			BUG_ON(PageUptodate(page));
-		else {
-#endif
-			page = __stagingpage_alloc(pagepool, gfp);
-
-			if (oldpage != cmpxchg(compressed_pages + i,
-				oldpage, page)) {
-				list_add(&page->lru, pagepool);
-				goto repeat;
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-			} else if (cachemngd && !add_to_page_cache_lru(page,
-				mngda, first_index + i, gfp)) {
-				set_page_private(page, (unsigned long)grp);
-				SetPagePrivate(page);
-#endif
-			}
-		}
-
-		if (bio != NULL && force_submit) {
-submit_bio_retry:
-			__submit_bio(bio, REQ_OP_READ, 0);
-			bio = NULL;
-		}
-
-		if (bio == NULL) {
-			bio = prepare_bio(sb, first_index + i,
-				BIO_MAX_PAGES, z_erofs_vle_read_endio);
-			bio->bi_private = tagptr_cast_ptr(bi_private);
-
-			++nr_bios;
-		}
-
-		err = bio_add_page(bio, page, PAGE_SIZE, 0);
-		if (err < PAGE_SIZE)
-			goto submit_bio_retry;
-
-		force_submit = false;
-		last_index = first_index + i;
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-skippage:
-#endif
-		if (++i < clusterpages)
-			goto repeat;
-
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-		if (noio < clusterpages) {
-			lstgrp_io = grp;
-		} else {
-			z_erofs_vle_owned_workgrp_t iogrp_next =
-				owned_head == Z_EROFS_VLE_WORKGRP_TAIL ?
-				Z_EROFS_VLE_WORKGRP_TAIL_CLOSED :
-				owned_head;
-
-			if (lstgrp_io == NULL)
-				ios[1]->head = iogrp_next;
-			else
-				WRITE_ONCE(lstgrp_io->next, iogrp_next);
-
-			if (lstgrp_noio == NULL)
-				ios[0]->head = grp;
-			else
-				WRITE_ONCE(lstgrp_noio->next, grp);
-
-			lstgrp_noio = grp;
-		}
-#endif
-	} while (owned_head != Z_EROFS_VLE_WORKGRP_TAIL);
-
-	if (bio != NULL)
-		__submit_bio(bio, REQ_OP_READ, 0);
-
-#ifndef EROFS_FS_HAS_MANAGED_CACHE
-	BUG_ON(!nr_bios);
-#else
-	if (lstgrp_noio != NULL)
-		WRITE_ONCE(lstgrp_noio->next, Z_EROFS_VLE_WORKGRP_TAIL_CLOSED);
-
-	if (!force_fg && !nr_bios) {
-		kvfree(container_of(ios[1],
-			struct z_erofs_vle_unzip_io_sb, io));
-		return true;
-	}
-#endif
-
-	z_erofs_vle_unzip_kickoff(tagptr_cast_ptr(bi_private), nr_bios);
-	return true;
-}
-
-static void z_erofs_submit_and_unzip(struct z_erofs_vle_frontend *f,
-				     struct list_head *pagepool,
-				     bool force_fg)
-{
-	struct super_block *sb = f->inode->i_sb;
-	struct z_erofs_vle_unzip_io io[1 + __FSIO_1];
-
-	if (!z_erofs_vle_submit_all(sb, f->owned_head, pagepool, io, force_fg))
-		return;
-
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-	z_erofs_vle_unzip_all(sb, &io[0], pagepool);
-#endif
-	if (!force_fg)
-		return;
-
-	/* wait until all bios are completed */
-	wait_event(io[__FSIO_1].u.wait,
-		!atomic_read(&io[__FSIO_1].pending_bios));
-
-	/* let's synchronous decompression */
-	z_erofs_vle_unzip_all(sb, &io[__FSIO_1], pagepool);
-}
-
-static int z_erofs_vle_normalaccess_readpage(struct file *file,
-					     struct page *page)
-{
-	struct inode *const inode = page->mapping->host;
-	struct z_erofs_vle_frontend f = VLE_FRONTEND_INIT(inode);
-	int err;
-	LIST_HEAD(pagepool);
-
-#if (EROFS_FS_ZIP_CACHE_LVL >= 2)
-	f.cachedzone_la = page->index << PAGE_SHIFT;
-#endif
-	err = z_erofs_do_read_page(&f, page, &pagepool);
-	(void)z_erofs_vle_work_iter_end(&f.builder);
-
-	/* if some compressed cluster ready, need submit them anyway */
-	z_erofs_submit_and_unzip(&f, &pagepool, true);
-
-	if (err)
-		errln("%s, failed to read, err [%d]", __func__, err);
-
-	if (f.m_iter.mpage != NULL)
-		put_page(f.m_iter.mpage);
-
-	/* clean up the remaining free pages */
-	put_pages_list(&pagepool);
-	return err;
-}
-
-static inline int __z_erofs_vle_normalaccess_readpages(
-	struct file *filp,
-	struct address_space *mapping,
-	struct list_head *pages, unsigned nr_pages, bool sync)
-{
-	struct inode *const inode = mapping->host;
-
-	struct z_erofs_vle_frontend f = VLE_FRONTEND_INIT(inode);
-	gfp_t gfp = mapping_gfp_constraint(mapping, GFP_KERNEL);
-	struct page *head = NULL;
-	LIST_HEAD(pagepool);
-
-#if (EROFS_FS_ZIP_CACHE_LVL >= 2)
-	f.cachedzone_la = lru_to_page(pages)->index << PAGE_SHIFT;
-#endif
-	for (; nr_pages; --nr_pages) {
-		struct page *page = lru_to_page(pages);
-
-		prefetchw(&page->flags);
-		list_del(&page->lru);
-
-		if (add_to_page_cache_lru(page, mapping, page->index, gfp)) {
-			list_add(&page->lru, &pagepool);
-			continue;
-		}
-
-		set_page_private(page, (unsigned long)head);
-		head = page;
-	}
-
-	while (head != NULL) {
-		struct page *page = head;
-		int err;
-
-		/* traversal in reverse order */
-		head = (void *)page_private(page);
-
-		err = z_erofs_do_read_page(&f, page, &pagepool);
-		if (err) {
-			struct erofs_vnode *vi = EROFS_V(inode);
-
-			errln("%s, readahead error at page %lu of nid %llu",
-				__func__, page->index, vi->nid);
-		}
-
-		put_page(page);
-	}
-
-	(void)z_erofs_vle_work_iter_end(&f.builder);
-
-	z_erofs_submit_and_unzip(&f, &pagepool, sync);
-
-	if (f.m_iter.mpage != NULL)
-		put_page(f.m_iter.mpage);
-
-	/* clean up the remaining free pages */
-	put_pages_list(&pagepool);
-	return 0;
-}
-
-static int z_erofs_vle_normalaccess_readpages(
-	struct file *filp,
-	struct address_space *mapping,
-	struct list_head *pages, unsigned nr_pages)
-{
-	return __z_erofs_vle_normalaccess_readpages(filp,
-		mapping, pages, nr_pages,
-		nr_pages < 4 /* sync */);
-}
-
-const struct address_space_operations z_erofs_vle_normalaccess_aops = {
-	.readpage = z_erofs_vle_normalaccess_readpage,
-	.readpages = z_erofs_vle_normalaccess_readpages,
-};
-
-#define __vle_cluster_advise(x, bit, bits) \
-	((le16_to_cpu(x) >> (bit)) & ((1 << (bits)) - 1))
-
-#define __vle_cluster_type(advise) __vle_cluster_advise(advise, \
-	Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT, Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS)
-
-enum {
-	Z_EROFS_VLE_CLUSTER_TYPE_PLAIN,
-	Z_EROFS_VLE_CLUSTER_TYPE_HEAD,
-	Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD,
-	Z_EROFS_VLE_CLUSTER_TYPE_RESERVED,
-	Z_EROFS_VLE_CLUSTER_TYPE_MAX
-};
-
-#define vle_cluster_type(di)	\
-	__vle_cluster_type((di)->di_advise)
-
-static inline unsigned
-vle_compressed_index_clusterofs(unsigned clustersize,
-	struct z_erofs_vle_decompressed_index *di)
-{
-	debugln("%s, vle=%pK, advise=%x (type %u), clusterofs=%x blkaddr=%x",
-		__func__, di, di->di_advise, vle_cluster_type(di),
-		di->di_clusterofs, di->di_u.blkaddr);
-
-	switch (vle_cluster_type(di)) {
-	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
-		break;
-	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
-	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
-		return di->di_clusterofs;
-	default:
-		BUG_ON(1);
-	}
-	return clustersize;
-}
-
-static inline erofs_blk_t
-vle_extent_blkaddr(struct inode *inode, pgoff_t index)
-{
-	struct erofs_sb_info *sbi = EROFS_I_SB(inode);
-	struct erofs_vnode *vi = EROFS_V(inode);
-
-	unsigned ofs = Z_EROFS_VLE_EXTENT_ALIGN(vi->inode_isize +
-		vi->xattr_isize) + sizeof(struct erofs_extent_header) +
-		index * sizeof(struct z_erofs_vle_decompressed_index);
-
-	return erofs_blknr(iloc(sbi, vi->nid) + ofs);
-}
-
-static inline unsigned int
-vle_extent_blkoff(struct inode *inode, pgoff_t index)
-{
-	struct erofs_sb_info *sbi = EROFS_I_SB(inode);
-	struct erofs_vnode *vi = EROFS_V(inode);
-
-	unsigned ofs = Z_EROFS_VLE_EXTENT_ALIGN(vi->inode_isize +
-		vi->xattr_isize) + sizeof(struct erofs_extent_header) +
-		index * sizeof(struct z_erofs_vle_decompressed_index);
-
-	return erofs_blkoff(iloc(sbi, vi->nid) + ofs);
-}
-
-/*
- * Variable-sized Logical Extent (Fixed Physical Cluster) Compression Mode
- * ---
- * VLE compression mode attempts to compress a number of logical data into
- * a physical cluster with a fixed size.
- * VLE compression mode uses "struct z_erofs_vle_decompressed_index".
- */
-static erofs_off_t vle_get_logical_extent_head(
-	struct inode *inode,
-	struct page **page_iter,
-	void **kaddr_iter,
-	unsigned lcn,	/* logical cluster number */
-	erofs_blk_t *pcn,
-	unsigned *flags)
-{
-	/* for extent meta */
-	struct page *page = *page_iter;
-	erofs_blk_t blkaddr = vle_extent_blkaddr(inode, lcn);
-	struct z_erofs_vle_decompressed_index *di;
-	unsigned long long ofs;
-	const unsigned int clusterbits = EROFS_SB(inode->i_sb)->clusterbits;
-	const unsigned int clustersize = 1 << clusterbits;
-	unsigned int delta0;
-
-	if (page->index != blkaddr) {
-		kunmap_atomic(*kaddr_iter);
-		unlock_page(page);
-		put_page(page);
-
-		*page_iter = page = erofs_get_meta_page(inode->i_sb,
-			blkaddr, false);
-		*kaddr_iter = kmap_atomic(page);
-	}
-
-	di = *kaddr_iter + vle_extent_blkoff(inode, lcn);
-	switch (vle_cluster_type(di)) {
-	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
-		delta0 = le16_to_cpu(di->di_u.delta[0]);
-		DBG_BUGON(!delta0);
-		DBG_BUGON(lcn < delta0);
-
-		ofs = vle_get_logical_extent_head(inode,
-			page_iter, kaddr_iter,
-			lcn - delta0, pcn, flags);
-		break;
-	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
-		*flags ^= EROFS_MAP_ZIPPED;
-	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
-		/* clustersize should be a power of two */
-		ofs = ((unsigned long long)lcn << clusterbits) +
-			(le16_to_cpu(di->di_clusterofs) & (clustersize - 1));
-		*pcn = le32_to_cpu(di->di_u.blkaddr);
-		break;
-	default:
-		BUG_ON(1);
-	}
-	return ofs;
-}
-
-int z_erofs_map_blocks_iter(struct inode *inode,
-	struct erofs_map_blocks *map,
-	struct page **mpage_ret, int flags)
-{
-	/* logicial extent (start, end) offset */
-	unsigned long long ofs, end;
-	struct z_erofs_vle_decompressed_index *di;
-	erofs_blk_t e_blkaddr, pcn;
-	unsigned lcn, logical_cluster_ofs, cluster_type;
-	u32 ofs_rem;
-	struct page *mpage = *mpage_ret;
-	void *kaddr;
-	bool initial;
-	const unsigned int clusterbits = EROFS_SB(inode->i_sb)->clusterbits;
-	const unsigned int clustersize = 1 << clusterbits;
-	int err = 0;
-
-	/* if both m_(l,p)len are 0, regularize l_lblk, l_lofs, etc... */
-	initial = !map->m_llen;
-
-	/* when trying to read beyond EOF, leave it unmapped */
-	if (unlikely(map->m_la >= inode->i_size)) {
-		BUG_ON(!initial);
-		map->m_llen = map->m_la + 1 - inode->i_size;
-		map->m_la = inode->i_size - 1;
-		map->m_flags = 0;
-		goto out;
-	}
-
-	debugln("%s, m_la %llu m_llen %llu --- start", __func__,
-		map->m_la, map->m_llen);
-
-	ofs = map->m_la + map->m_llen;
-
-	/* clustersize should be power of two */
-	lcn = ofs >> clusterbits;
-	ofs_rem = ofs & (clustersize - 1);
-
-	e_blkaddr = vle_extent_blkaddr(inode, lcn);
-
-	if (mpage == NULL || mpage->index != e_blkaddr) {
-		if (mpage != NULL)
-			put_page(mpage);
-
-		mpage = erofs_get_meta_page(inode->i_sb, e_blkaddr, false);
-		*mpage_ret = mpage;
-	} else {
-		lock_page(mpage);
-		DBG_BUGON(!PageUptodate(mpage));
-	}
-
-	kaddr = kmap_atomic(mpage);
-	di = kaddr + vle_extent_blkoff(inode, lcn);
-
-	debugln("%s, lcn %u e_blkaddr %u e_blkoff %u", __func__, lcn,
-		e_blkaddr, vle_extent_blkoff(inode, lcn));
-
-	logical_cluster_ofs = vle_compressed_index_clusterofs(clustersize, di);
-	if (!initial) {
-		/* [walking mode] 'map' has been already initialized */
-		map->m_llen += logical_cluster_ofs;
-		goto unmap_out;
-	}
-
-	/* by default, compressed */
-	map->m_flags |= EROFS_MAP_ZIPPED;
-
-	end = (u64)(lcn + 1) * clustersize;
-
-	cluster_type = vle_cluster_type(di);
-
-	switch (cluster_type) {
-	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
-		if (ofs_rem >= logical_cluster_ofs)
-			map->m_flags ^= EROFS_MAP_ZIPPED;
-		/* fallthrough */
-	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
-		if (ofs_rem == logical_cluster_ofs) {
-			pcn = le32_to_cpu(di->di_u.blkaddr);
-			goto exact_hitted;
-		}
-
-		if (ofs_rem > logical_cluster_ofs) {
-			ofs = lcn * clustersize | logical_cluster_ofs;
-			pcn = le32_to_cpu(di->di_u.blkaddr);
-			break;
-		}
-
-		/* logical cluster number should be >= 1 */
-		if (unlikely(!lcn)) {
-			errln("invalid logical cluster 0 at nid %llu",
-				EROFS_V(inode)->nid);
-			err = -EIO;
-			goto unmap_out;
-		}
-		end = (lcn-- * clustersize) | logical_cluster_ofs;
-		/* fallthrough */
-	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
-		/* get the correspoinding first chunk */
-		ofs = vle_get_logical_extent_head(inode, mpage_ret,
-			&kaddr, lcn, &pcn, &map->m_flags);
-		mpage = *mpage_ret;
-		break;
-	default:
-		errln("unknown cluster type %u at offset %llu of nid %llu",
-			cluster_type, ofs, EROFS_V(inode)->nid);
-		err = -EIO;
-		goto unmap_out;
-	}
-
-	map->m_la = ofs;
-exact_hitted:
-	map->m_llen = end - ofs;
-	map->m_plen = clustersize;
-	map->m_pa = blknr_to_addr(pcn);
-	map->m_flags |= EROFS_MAP_MAPPED;
-unmap_out:
-	kunmap_atomic(kaddr);
-	unlock_page(mpage);
-out:
-	debugln("%s, m_la %llu m_pa %llu m_llen %llu m_plen %llu m_flags 0%o",
-		__func__, map->m_la, map->m_pa,
-		map->m_llen, map->m_plen, map->m_flags);
-
-	/* aggressively BUG_ON iff CONFIG_EROFS_FS_DEBUG is on */
-	DBG_BUGON(err < 0);
-	return err;
-}
-
diff --git a/drivers/staging/erofs/unzip_vle_lz4.c b/drivers/staging/erofs/unzip_vle_lz4.c
deleted file mode 100644
index 3a7428317f0a..000000000000
--- a/drivers/staging/erofs/unzip_vle_lz4.c
+++ /dev/null
@@ -1,210 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * linux/drivers/staging/erofs/unzip_vle_lz4.c
- *
- * Copyright (C) 2018 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
- */
-#include "unzip_vle.h"
-
-#if Z_EROFS_CLUSTER_MAX_PAGES > Z_EROFS_VLE_INLINE_PAGEVECS
-#define EROFS_PERCPU_NR_PAGES   Z_EROFS_CLUSTER_MAX_PAGES
-#else
-#define EROFS_PERCPU_NR_PAGES   Z_EROFS_VLE_INLINE_PAGEVECS
-#endif
-
-static struct {
-	char data[PAGE_SIZE * EROFS_PERCPU_NR_PAGES];
-} erofs_pcpubuf[NR_CPUS];
-
-int z_erofs_vle_plain_copy(struct page **compressed_pages,
-			   unsigned clusterpages,
-			   struct page **pages,
-			   unsigned nr_pages,
-			   unsigned short pageofs)
-{
-	unsigned i, j;
-	void *src = NULL;
-	const unsigned righthalf = PAGE_SIZE - pageofs;
-	char *percpu_data;
-	bool mirrored[Z_EROFS_CLUSTER_MAX_PAGES] = { 0 };
-
-	preempt_disable();
-	percpu_data = erofs_pcpubuf[smp_processor_id()].data;
-
-	j = 0;
-	for (i = 0; i < nr_pages; j = i++) {
-		struct page *page = pages[i];
-		void *dst;
-
-		if (page == NULL) {
-			if (src != NULL) {
-				if (!mirrored[j])
-					kunmap_atomic(src);
-				src = NULL;
-			}
-			continue;
-		}
-
-		dst = kmap_atomic(page);
-
-		for (; j < clusterpages; ++j) {
-			if (compressed_pages[j] != page)
-				continue;
-
-			DBG_BUGON(mirrored[j]);
-			memcpy(percpu_data + j * PAGE_SIZE, dst, PAGE_SIZE);
-			mirrored[j] = true;
-			break;
-		}
-
-		if (i) {
-			if (src == NULL)
-				src = mirrored[i-1] ?
-					percpu_data + (i-1) * PAGE_SIZE :
-					kmap_atomic(compressed_pages[i-1]);
-
-			memcpy(dst, src + righthalf, pageofs);
-
-			if (!mirrored[i-1])
-				kunmap_atomic(src);
-
-			if (unlikely(i >= clusterpages)) {
-				kunmap_atomic(dst);
-				break;
-			}
-		}
-
-		if (!righthalf)
-			src = NULL;
-		else {
-			src = mirrored[i] ? percpu_data + i * PAGE_SIZE :
-				kmap_atomic(compressed_pages[i]);
-
-			memcpy(dst + pageofs, src, righthalf);
-		}
-
-		kunmap_atomic(dst);
-	}
-
-	if (src != NULL && !mirrored[j])
-		kunmap_atomic(src);
-
-	preempt_enable();
-	return 0;
-}
-
-extern int z_erofs_unzip_lz4(void *in, void *out, size_t inlen, size_t outlen);
-
-int z_erofs_vle_unzip_fast_percpu(struct page **compressed_pages,
-				  unsigned clusterpages,
-				  struct page **pages,
-				  unsigned outlen,
-				  unsigned short pageofs)
-{
-	void *vin, *vout;
-	unsigned nr_pages, i, j;
-	int ret;
-
-	if (outlen + pageofs > EROFS_PERCPU_NR_PAGES * PAGE_SIZE)
-		return -ENOTSUPP;
-
-	nr_pages = DIV_ROUND_UP(outlen + pageofs, PAGE_SIZE);
-
-	if (clusterpages == 1) {
-		vin = kmap_atomic(compressed_pages[0]);
-	} else {
-		vin = erofs_vmap(compressed_pages, clusterpages);
-		if (!vin)
-			return -ENOMEM;
-	}
-
-	preempt_disable();
-	vout = erofs_pcpubuf[smp_processor_id()].data;
-
-	ret = z_erofs_unzip_lz4(vin, vout + pageofs,
-		clusterpages * PAGE_SIZE, outlen);
-
-	if (ret < 0)
-		goto out;
-	ret = 0;
-
-	for (i = 0; i < nr_pages; ++i) {
-		j = min((unsigned)PAGE_SIZE - pageofs, outlen);
-
-		if (pages[i] != NULL) {
-			if (clusterpages == 1 &&
-			    pages[i] == compressed_pages[0]) {
-				memcpy(vin + pageofs, vout + pageofs, j);
-			} else {
-				void *dst = kmap_atomic(pages[i]);
-
-				memcpy(dst + pageofs, vout + pageofs, j);
-				kunmap_atomic(dst);
-			}
-		}
-		vout += PAGE_SIZE;
-		outlen -= j;
-		pageofs = 0;
-	}
-
-out:
-	preempt_enable();
-
-	if (clusterpages == 1)
-		kunmap_atomic(vin);
-	else
-		erofs_vunmap(vin, clusterpages);
-
-	return ret;
-}
-
-int z_erofs_vle_unzip_vmap(struct page **compressed_pages,
-			   unsigned clusterpages,
-			   void *vout,
-			   unsigned llen,
-			   unsigned short pageofs,
-			   bool overlapped)
-{
-	void *vin;
-	unsigned i;
-	int ret;
-
-	if (overlapped) {
-		preempt_disable();
-		vin = erofs_pcpubuf[smp_processor_id()].data;
-
-		for (i = 0; i < clusterpages; ++i) {
-			void *t = kmap_atomic(compressed_pages[i]);
-
-			memcpy(vin + PAGE_SIZE *i, t, PAGE_SIZE);
-			kunmap_atomic(t);
-		}
-	} else if (clusterpages == 1)
-		vin = kmap_atomic(compressed_pages[0]);
-	else {
-		vin = erofs_vmap(compressed_pages, clusterpages);
-	}
-
-	ret = z_erofs_unzip_lz4(vin, vout + pageofs,
-		clusterpages * PAGE_SIZE, llen);
-	if (ret > 0)
-		ret = 0;
-
-	if (!overlapped) {
-		if (clusterpages == 1)
-			kunmap_atomic(vin);
-		else {
-			erofs_vunmap(vin, clusterpages);
-		}
-	} else
-		preempt_enable();
-
-	return ret;
-}
-
diff --git a/drivers/staging/erofs/utils.c b/drivers/staging/erofs/utils.c
index 4de9c39535eb..aab4a607f028 100644
--- a/drivers/staging/erofs/utils.c
+++ b/drivers/staging/erofs/utils.c
@@ -1,16 +1,8 @@
-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
- * linux/drivers/staging/erofs/utils.c
- *
  * Copyright (C) 2018 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
+ *             https://www.huawei.com/
  */
-
 #include "internal.h"
 #include <linux/pagevec.h>
 
@@ -20,43 +12,67 @@ struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp)
 
 	if (!list_empty(pool)) {
 		page = lru_to_page(pool);
+		DBG_BUGON(page_ref_count(page) != 1);
 		list_del(&page->lru);
 	} else {
-		page = alloc_pages(gfp | __GFP_NOFAIL, 0);
+		page = alloc_page(gfp);
 	}
 	return page;
 }
 
+#if (EROFS_PCPUBUF_NR_PAGES > 0)
+static struct {
+	u8 data[PAGE_SIZE * EROFS_PCPUBUF_NR_PAGES];
+} ____cacheline_aligned_in_smp erofs_pcpubuf[NR_CPUS];
+
+void *erofs_get_pcpubuf(unsigned int pagenr)
+{
+	preempt_disable();
+	return &erofs_pcpubuf[smp_processor_id()].data[pagenr * PAGE_SIZE];
+}
+#endif
+
+#ifdef CONFIG_EROFS_FS_ZIP
 /* global shrink count (for all mounted EROFS instances) */
 static atomic_long_t erofs_global_shrink_cnt;
 
-#ifdef CONFIG_EROFS_FS_ZIP
+#define __erofs_workgroup_get(grp)	atomic_inc(&(grp)->refcount)
+#define __erofs_workgroup_put(grp)	atomic_dec(&(grp)->refcount)
 
-/* radix_tree and the future XArray both don't use tagptr_t yet */
-struct erofs_workgroup *erofs_find_workgroup(
-	struct super_block *sb, pgoff_t index, bool *tag)
+static int erofs_workgroup_get(struct erofs_workgroup *grp)
+{
+	int o;
+
+repeat:
+	o = erofs_wait_on_workgroup_freezed(grp);
+	if (o <= 0)
+		return -1;
+
+	if (atomic_cmpxchg(&grp->refcount, o, o + 1) != o)
+		goto repeat;
+
+	/* decrease refcount paired by erofs_workgroup_put */
+	if (o == 1)
+		atomic_long_dec(&erofs_global_shrink_cnt);
+	return 0;
+}
+
+struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
+					     pgoff_t index)
 {
 	struct erofs_sb_info *sbi = EROFS_SB(sb);
 	struct erofs_workgroup *grp;
-	int oldcount;
 
 repeat:
 	rcu_read_lock();
 	grp = radix_tree_lookup(&sbi->workstn_tree, index);
-	if (grp != NULL) {
-		*tag = radix_tree_exceptional_entry(grp);
-		grp = (void *)((unsigned long)grp &
-			~RADIX_TREE_EXCEPTIONAL_ENTRY);
-
-		if (erofs_workgroup_get(grp, &oldcount)) {
+	if (grp) {
+		if (erofs_workgroup_get(grp)) {
 			/* prefer to relax rcu read side */
 			rcu_read_unlock();
 			goto repeat;
 		}
 
-		/* decrease refcount added by erofs_workgroup_put */
-		if (unlikely(oldcount == 1))
-			atomic_long_dec(&erofs_global_shrink_cnt);
 		DBG_BUGON(index != grp->index);
 	}
 	rcu_read_unlock();
@@ -64,14 +80,13 @@ repeat:
 }
 
 int erofs_register_workgroup(struct super_block *sb,
-			     struct erofs_workgroup *grp,
-			     bool tag)
+			     struct erofs_workgroup *grp)
 {
 	struct erofs_sb_info *sbi;
 	int err;
 
 	/* grp shouldn't be broken or used before */
-	if (unlikely(atomic_read(&grp->refcount) != 1)) {
+	if (atomic_read(&grp->refcount) != 1) {
 		DBG_BUGON(1);
 		return -EINVAL;
 	}
@@ -81,35 +96,28 @@ int erofs_register_workgroup(struct super_block *sb,
 		return err;
 
 	sbi = EROFS_SB(sb);
-	erofs_workstn_lock(sbi);
-
-	if (tag)
-		grp = (void *)((unsigned long)grp |
-			1UL << RADIX_TREE_EXCEPTIONAL_SHIFT);
+	xa_lock(&sbi->workstn_tree);
 
 	/*
 	 * Bump up reference count before making this workgroup
 	 * visible to other users in order to avoid potential UAF
-	 * without serialized by erofs_workstn_lock.
+	 * without serialized by workstn_lock.
 	 */
 	__erofs_workgroup_get(grp);
 
-	err = radix_tree_insert(&sbi->workstn_tree,
-				grp->index, grp);
-	if (unlikely(err))
+	err = radix_tree_insert(&sbi->workstn_tree, grp->index, grp);
+	if (err)
 		/*
 		 * it's safe to decrease since the workgroup isn't visible
 		 * and refcount >= 2 (cannot be freezed).
 		 */
 		__erofs_workgroup_put(grp);
 
-	erofs_workstn_unlock(sbi);
+	xa_unlock(&sbi->workstn_tree);
 	radix_tree_preload_end();
 	return err;
 }
 
-extern void erofs_workgroup_free_rcu(struct erofs_workgroup *grp);
-
 static void  __erofs_workgroup_free(struct erofs_workgroup *grp)
 {
 	atomic_long_dec(&erofs_global_shrink_cnt);
@@ -127,33 +135,22 @@ int erofs_workgroup_put(struct erofs_workgroup *grp)
 	return count;
 }
 
-#ifdef EROFS_FS_HAS_MANAGED_CACHE
-/* for cache-managed case, customized reclaim paths exist */
-static void erofs_workgroup_unfreeze_final(struct erofs_workgroup *grp)
+static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
+					   struct erofs_workgroup *grp)
 {
-	erofs_workgroup_unfreeze(grp, 0);
-	__erofs_workgroup_free(grp);
-}
-
-bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
-				    struct erofs_workgroup *grp,
-				    bool cleanup)
-{
-	void *entry;
-
 	/*
-	 * for managed cache enabled, the refcount of workgroups
-	 * themselves could be < 0 (freezed). So there is no guarantee
-	 * that all refcount > 0 if managed cache is enabled.
+	 * If managed cache is on, refcount of workgroups
+	 * themselves could be < 0 (freezed). In other words,
+	 * there is no guarantee that all refcounts > 0.
 	 */
 	if (!erofs_workgroup_try_to_freeze(grp, 1))
 		return false;
 
 	/*
-	 * note that all cached pages should be unlinked
-	 * before delete it from the radix tree.
-	 * Otherwise some cached pages of an orphan old workgroup
-	 * could be still linked after the new one is available.
+	 * Note that all cached pages should be unattached
+	 * before deleted from the radix tree. Otherwise some
+	 * cached pages could be still attached to the orphan
+	 * old workgroup when the new one is available in the tree.
 	 */
 	if (erofs_try_to_free_all_cached_pages(sbi, grp)) {
 		erofs_workgroup_unfreeze(grp, 1);
@@ -161,87 +158,52 @@ bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
 	}
 
 	/*
-	 * it is impossible to fail after the workgroup is freezed,
+	 * It's impossible to fail after the workgroup is freezed,
 	 * however in order to avoid some race conditions, add a
 	 * DBG_BUGON to observe this in advance.
 	 */
-	entry = radix_tree_delete(&sbi->workstn_tree, grp->index);
-	DBG_BUGON((void *)((unsigned long)entry &
-			   ~RADIX_TREE_EXCEPTIONAL_ENTRY) != grp);
+	DBG_BUGON(radix_tree_delete(&sbi->workstn_tree, grp->index) != grp);
 
-	/*
-	 * if managed cache is enable, the last refcount
-	 * should indicate the related workstation.
-	 */
-	erofs_workgroup_unfreeze_final(grp);
-	return true;
-}
-
-#else
-/* for nocache case, no customized reclaim path at all */
-bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
-				    struct erofs_workgroup *grp,
-				    bool cleanup)
-{
-	int cnt = atomic_read(&grp->refcount);
-	void *entry;
-
-	DBG_BUGON(cnt <= 0);
-	DBG_BUGON(cleanup && cnt != 1);
-
-	if (cnt > 1)
-		return false;
-
-	entry = radix_tree_delete(&sbi->workstn_tree, grp->index);
-	DBG_BUGON((void *)((unsigned long)entry &
-			   ~RADIX_TREE_EXCEPTIONAL_ENTRY) != grp);
-
-	/* (rarely) could be grabbed again when freeing */
-	erofs_workgroup_put(grp);
+	/* last refcount should be connected with its managed pslot.  */
+	erofs_workgroup_unfreeze(grp, 0);
+	__erofs_workgroup_free(grp);
 	return true;
 }
 
-#endif
-
-unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi,
-				       unsigned long nr_shrink,
-				       bool cleanup)
+static unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi,
+					      unsigned long nr_shrink)
 {
 	pgoff_t first_index = 0;
 	void *batch[PAGEVEC_SIZE];
-	unsigned freed = 0;
+	unsigned int freed = 0;
 
 	int i, found;
 repeat:
-	erofs_workstn_lock(sbi);
+	xa_lock(&sbi->workstn_tree);
 
 	found = radix_tree_gang_lookup(&sbi->workstn_tree,
-		batch, first_index, PAGEVEC_SIZE);
+				       batch, first_index, PAGEVEC_SIZE);
 
 	for (i = 0; i < found; ++i) {
-		struct erofs_workgroup *grp = (void *)
-			((unsigned long)batch[i] &
-				~RADIX_TREE_EXCEPTIONAL_ENTRY);
+		struct erofs_workgroup *grp = batch[i];
 
 		first_index = grp->index + 1;
 
 		/* try to shrink each valid workgroup */
-		if (!erofs_try_to_release_workgroup(sbi, grp, cleanup))
+		if (!erofs_try_to_release_workgroup(sbi, grp))
 			continue;
 
 		++freed;
-		if (unlikely(!--nr_shrink))
+		if (!--nr_shrink)
 			break;
 	}
-	erofs_workstn_unlock(sbi);
+	xa_unlock(&sbi->workstn_tree);
 
 	if (i && nr_shrink)
 		goto repeat;
 	return freed;
 }
 
-#endif
-
 /* protected by 'erofs_sb_list_lock' */
 static unsigned int shrinker_run_no;
 
@@ -249,7 +211,7 @@ static unsigned int shrinker_run_no;
 static DEFINE_SPINLOCK(erofs_sb_list_lock);
 static LIST_HEAD(erofs_sb_list);
 
-void erofs_register_super(struct super_block *sb)
+void erofs_shrinker_register(struct super_block *sb)
 {
 	struct erofs_sb_info *sbi = EROFS_SB(sb);
 
@@ -260,21 +222,28 @@ void erofs_register_super(struct super_block *sb)
 	spin_unlock(&erofs_sb_list_lock);
 }
 
-void erofs_unregister_super(struct super_block *sb)
+void erofs_shrinker_unregister(struct super_block *sb)
 {
+	struct erofs_sb_info *const sbi = EROFS_SB(sb);
+
+	mutex_lock(&sbi->umount_mutex);
+	/* clean up all remaining workgroups in memory */
+	erofs_shrink_workstation(sbi, ~0UL);
+
 	spin_lock(&erofs_sb_list_lock);
-	list_del(&EROFS_SB(sb)->list);
+	list_del(&sbi->list);
 	spin_unlock(&erofs_sb_list_lock);
+	mutex_unlock(&sbi->umount_mutex);
 }
 
-unsigned long erofs_shrink_count(struct shrinker *shrink,
-				 struct shrink_control *sc)
+static unsigned long erofs_shrink_count(struct shrinker *shrink,
+					struct shrink_control *sc)
 {
 	return atomic_long_read(&erofs_global_shrink_cnt);
 }
 
-unsigned long erofs_shrink_scan(struct shrinker *shrink,
-				struct shrink_control *sc)
+static unsigned long erofs_shrink_scan(struct shrinker *shrink,
+				       struct shrink_control *sc)
 {
 	struct erofs_sb_info *sbi;
 	struct list_head *p;
@@ -284,9 +253,9 @@ unsigned long erofs_shrink_scan(struct shrinker *shrink,
 	unsigned long freed = 0;
 
 	spin_lock(&erofs_sb_list_lock);
-	do
+	do {
 		run_no = ++shrinker_run_no;
-	while (run_no == 0);
+	} while (run_no == 0);
 
 	/* Iterate over all mounted superblocks and try to shrink them */
 	p = erofs_sb_list.next;
@@ -308,9 +277,7 @@ unsigned long erofs_shrink_scan(struct shrinker *shrink,
 		spin_unlock(&erofs_sb_list_lock);
 		sbi->shrinker_run_no = run_no;
 
-#ifdef CONFIG_EROFS_FS_ZIP
-		freed += erofs_shrink_workstation(sbi, nr - freed, false);
-#endif
+		freed += erofs_shrink_workstation(sbi, nr - freed);
 
 		spin_lock(&erofs_sb_list_lock);
 		/* Get the next list element before we move this one */
@@ -330,3 +297,19 @@ unsigned long erofs_shrink_scan(struct shrinker *shrink,
 	return freed;
 }
 
+static struct shrinker erofs_shrinker_info = {
+	.scan_objects = erofs_shrink_scan,
+	.count_objects = erofs_shrink_count,
+	.seeks = DEFAULT_SEEKS,
+};
+
+int __init erofs_init_shrinker(void)
+{
+	return register_shrinker(&erofs_shrinker_info);
+}
+
+void erofs_exit_shrinker(void)
+{
+	unregister_shrinker(&erofs_shrinker_info);
+}
+#endif	/* !CONFIG_EROFS_FS_ZIP */
diff --git a/drivers/staging/erofs/xattr.c b/drivers/staging/erofs/xattr.c
index d48687ca2199..2b9bb3a7a5f2 100644
--- a/drivers/staging/erofs/xattr.c
+++ b/drivers/staging/erofs/xattr.c
@@ -1,14 +1,7 @@
-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
- * linux/drivers/staging/erofs/xattr.c
- *
  * Copyright (C) 2017-2018 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
+ *             https://www.huawei.com/
  */
 #include <linux/security.h>
 #include "xattr.h"
@@ -19,13 +12,13 @@ struct xattr_iter {
 	void *kaddr;
 
 	erofs_blk_t blkaddr;
-	unsigned ofs;
+	unsigned int ofs;
 };
 
 static inline void xattr_iter_end(struct xattr_iter *it, bool atomic)
 {
 	/* the only user of kunmap() is 'init_inode_xattrs' */
-	if (unlikely(!atomic))
+	if (!atomic)
 		kunmap(it->page);
 	else
 		kunmap_atomic(it->kaddr);
@@ -44,23 +37,30 @@ static inline void xattr_iter_end_final(struct xattr_iter *it)
 
 static int init_inode_xattrs(struct inode *inode)
 {
-	struct erofs_vnode *const vi = EROFS_V(inode);
+	struct erofs_inode *const vi = EROFS_I(inode);
 	struct xattr_iter it;
-	unsigned i;
+	unsigned int i;
 	struct erofs_xattr_ibody_header *ih;
+	struct super_block *sb;
 	struct erofs_sb_info *sbi;
 	bool atomic_map;
 	int ret = 0;
 
 	/* the most case is that xattrs of this inode are initialized. */
-	if (test_bit(EROFS_V_EA_INITED_BIT, &vi->flags))
+	if (test_bit(EROFS_I_EA_INITED_BIT, &vi->flags)) {
+		/*
+		 * paired with smp_mb() at the end of the function to ensure
+		 * fields will only be observed after the bit is set.
+		 */
+		smp_mb();
 		return 0;
+	}
 
-	if (wait_on_bit_lock(&vi->flags, EROFS_V_BL_XATTR_BIT, TASK_KILLABLE))
+	if (wait_on_bit_lock(&vi->flags, EROFS_I_BL_XATTR_BIT, TASK_KILLABLE))
 		return -ERESTARTSYS;
 
 	/* someone has initialized xattrs for us? */
-	if (test_bit(EROFS_V_EA_INITED_BIT, &vi->flags))
+	if (test_bit(EROFS_I_EA_INITED_BIT, &vi->flags))
 		goto out_unlock;
 
 	/*
@@ -72,25 +72,29 @@ static int init_inode_xattrs(struct inode *inode)
 	 *    undefined right now (maybe use later with some new sb feature).
 	 */
 	if (vi->xattr_isize == sizeof(struct erofs_xattr_ibody_header)) {
-		errln("xattr_isize %d of nid %llu is not supported yet",
-		      vi->xattr_isize, vi->nid);
-		ret = -ENOTSUPP;
+		erofs_err(inode->i_sb,
+			  "xattr_isize %d of nid %llu is not supported yet",
+			  vi->xattr_isize, vi->nid);
+		ret = -EOPNOTSUPP;
 		goto out_unlock;
 	} else if (vi->xattr_isize < sizeof(struct erofs_xattr_ibody_header)) {
-		if (unlikely(vi->xattr_isize)) {
+		if (vi->xattr_isize) {
+			erofs_err(inode->i_sb,
+				  "bogus xattr ibody @ nid %llu", vi->nid);
 			DBG_BUGON(1);
-			ret = -EIO;
+			ret = -EFSCORRUPTED;
 			goto out_unlock;	/* xattr ondisk layout error */
 		}
 		ret = -ENOATTR;
 		goto out_unlock;
 	}
 
-	sbi = EROFS_I_SB(inode);
+	sb = inode->i_sb;
+	sbi = EROFS_SB(sb);
 	it.blkaddr = erofs_blknr(iloc(sbi, vi->nid) + vi->inode_isize);
 	it.ofs = erofs_blkoff(iloc(sbi, vi->nid) + vi->inode_isize);
 
-	it.page = erofs_get_inline_page(inode, it.blkaddr);
+	it.page = erofs_get_meta_page(sb, it.blkaddr);
 	if (IS_ERR(it.page)) {
 		ret = PTR_ERR(it.page);
 		goto out_unlock;
@@ -115,13 +119,12 @@ static int init_inode_xattrs(struct inode *inode)
 	it.ofs += sizeof(struct erofs_xattr_ibody_header);
 
 	for (i = 0; i < vi->xattr_shared_count; ++i) {
-		if (unlikely(it.ofs >= EROFS_BLKSIZ)) {
+		if (it.ofs >= EROFS_BLKSIZ) {
 			/* cannot be unaligned */
-			BUG_ON(it.ofs != EROFS_BLKSIZ);
+			DBG_BUGON(it.ofs != EROFS_BLKSIZ);
 			xattr_iter_end(&it, atomic_map);
 
-			it.page = erofs_get_meta_page(inode->i_sb,
-				++it.blkaddr, S_ISDIR(inode->i_mode));
+			it.page = erofs_get_meta_page(sb, ++it.blkaddr);
 			if (IS_ERR(it.page)) {
 				kfree(vi->xattr_shared_xattrs);
 				vi->xattr_shared_xattrs = NULL;
@@ -139,18 +142,29 @@ static int init_inode_xattrs(struct inode *inode)
 	}
 	xattr_iter_end(&it, atomic_map);
 
-	set_bit(EROFS_V_EA_INITED_BIT, &vi->flags);
+	/* paired with smp_mb() at the beginning of the function. */
+	smp_mb();
+	set_bit(EROFS_I_EA_INITED_BIT, &vi->flags);
 
 out_unlock:
-	clear_and_wake_up_bit(EROFS_V_BL_XATTR_BIT, &vi->flags);
+	clear_and_wake_up_bit(EROFS_I_BL_XATTR_BIT, &vi->flags);
 	return ret;
 }
 
+/*
+ * the general idea for these return values is
+ * if    0 is returned, go on processing the current xattr;
+ *       1 (> 0) is returned, skip this round to process the next xattr;
+ *    -err (< 0) is returned, an error (maybe ENOXATTR) occurred
+ *                            and need to be handled
+ */
 struct xattr_iter_handlers {
-	int (*entry)(struct xattr_iter *, struct erofs_xattr_entry *);
-	int (*name)(struct xattr_iter *, unsigned, char *, unsigned);
-	int (*alloc_buffer)(struct xattr_iter *, unsigned);
-	void (*value)(struct xattr_iter *, unsigned, char *, unsigned);
+	int (*entry)(struct xattr_iter *_it, struct erofs_xattr_entry *entry);
+	int (*name)(struct xattr_iter *_it, unsigned int processed, char *buf,
+		    unsigned int len);
+	int (*alloc_buffer)(struct xattr_iter *_it, unsigned int value_sz);
+	void (*value)(struct xattr_iter *_it, unsigned int processed, char *buf,
+		      unsigned int len);
 };
 
 static inline int xattr_iter_fixup(struct xattr_iter *it)
@@ -161,7 +175,8 @@ static inline int xattr_iter_fixup(struct xattr_iter *it)
 	xattr_iter_end(it, true);
 
 	it->blkaddr += erofs_blknr(it->ofs);
-	it->page = erofs_get_meta_page(it->sb, it->blkaddr, false);
+
+	it->page = erofs_get_meta_page(it->sb, it->blkaddr);
 	if (IS_ERR(it->page)) {
 		int err = PTR_ERR(it->page);
 
@@ -175,15 +190,15 @@ static inline int xattr_iter_fixup(struct xattr_iter *it)
 }
 
 static int inline_xattr_iter_begin(struct xattr_iter *it,
-	struct inode *inode)
+				   struct inode *inode)
 {
-	struct erofs_vnode *const vi = EROFS_V(inode);
+	struct erofs_inode *const vi = EROFS_I(inode);
 	struct erofs_sb_info *const sbi = EROFS_SB(inode->i_sb);
-	unsigned xattr_header_sz, inline_xattr_ofs;
+	unsigned int xattr_header_sz, inline_xattr_ofs;
 
 	xattr_header_sz = inlinexattr_header_size(inode);
-	if (unlikely(xattr_header_sz >= vi->xattr_isize)) {
-		BUG_ON(xattr_header_sz > vi->xattr_isize);
+	if (xattr_header_sz >= vi->xattr_isize) {
+		DBG_BUGON(xattr_header_sz > vi->xattr_isize);
 		return -ENOATTR;
 	}
 
@@ -192,7 +207,7 @@ static int inline_xattr_iter_begin(struct xattr_iter *it,
 	it->blkaddr = erofs_blknr(iloc(sbi, vi->nid) + inline_xattr_ofs);
 	it->ofs = erofs_blkoff(iloc(sbi, vi->nid) + inline_xattr_ofs);
 
-	it->page = erofs_get_inline_page(inode, it->blkaddr);
+	it->page = erofs_get_meta_page(inode->i_sb, it->blkaddr);
 	if (IS_ERR(it->page))
 		return PTR_ERR(it->page);
 
@@ -200,11 +215,16 @@ static int inline_xattr_iter_begin(struct xattr_iter *it,
 	return vi->xattr_isize - xattr_header_sz;
 }
 
+/*
+ * Regardless of success or failure, `xattr_foreach' will end up with
+ * `ofs' pointing to the next xattr item rather than an arbitrary position.
+ */
 static int xattr_foreach(struct xattr_iter *it,
-	const struct xattr_iter_handlers *op, unsigned int *tlimit)
+			 const struct xattr_iter_handlers *op,
+			 unsigned int *tlimit)
 {
 	struct erofs_xattr_entry entry;
-	unsigned value_sz, processed, slice;
+	unsigned int value_sz, processed, slice;
 	int err;
 
 	/* 0. fixup blkaddr, ofs, ipage */
@@ -218,10 +238,14 @@ static int xattr_foreach(struct xattr_iter *it,
 	 *    therefore entry should be in the page
 	 */
 	entry = *(struct erofs_xattr_entry *)(it->kaddr + it->ofs);
-	if (tlimit != NULL) {
-		unsigned entry_sz = EROFS_XATTR_ENTRY_SIZE(&entry);
+	if (tlimit) {
+		unsigned int entry_sz = erofs_xattr_entry_size(&entry);
 
-		BUG_ON(*tlimit < entry_sz);
+		/* xattr on-disk corruption: xattr entry beyond xattr_isize */
+		if (*tlimit < entry_sz) {
+			DBG_BUGON(1);
+			return -EFSCORRUPTED;
+		}
 		*tlimit -= entry_sz;
 	}
 
@@ -240,7 +264,7 @@ static int xattr_foreach(struct xattr_iter *it,
 
 	while (processed < entry.e_name_len) {
 		if (it->ofs >= EROFS_BLKSIZ) {
-			BUG_ON(it->ofs > EROFS_BLKSIZ);
+			DBG_BUGON(it->ofs > EROFS_BLKSIZ);
 
 			err = xattr_iter_fixup(it);
 			if (err)
@@ -248,8 +272,8 @@ static int xattr_foreach(struct xattr_iter *it,
 			it->ofs = 0;
 		}
 
-		slice = min_t(unsigned, PAGE_SIZE - it->ofs,
-			entry.e_name_len - processed);
+		slice = min_t(unsigned int, PAGE_SIZE - it->ofs,
+			      entry.e_name_len - processed);
 
 		/* handle name */
 		err = op->name(it, processed, it->kaddr + it->ofs, slice);
@@ -265,7 +289,7 @@ static int xattr_foreach(struct xattr_iter *it,
 	/* 3. handle xattr value */
 	processed = 0;
 
-	if (op->alloc_buffer != NULL) {
+	if (op->alloc_buffer) {
 		err = op->alloc_buffer(it, value_sz);
 		if (err) {
 			it->ofs += value_sz;
@@ -275,7 +299,7 @@ static int xattr_foreach(struct xattr_iter *it,
 
 	while (processed < value_sz) {
 		if (it->ofs >= EROFS_BLKSIZ) {
-			BUG_ON(it->ofs > EROFS_BLKSIZ);
+			DBG_BUGON(it->ofs > EROFS_BLKSIZ);
 
 			err = xattr_iter_fixup(it);
 			if (err)
@@ -283,17 +307,17 @@ static int xattr_foreach(struct xattr_iter *it,
 			it->ofs = 0;
 		}
 
-		slice = min_t(unsigned, PAGE_SIZE - it->ofs,
-			value_sz - processed);
+		slice = min_t(unsigned int, PAGE_SIZE - it->ofs,
+			      value_sz - processed);
 		op->value(it, processed, it->kaddr + it->ofs, slice);
 		it->ofs += slice;
 		processed += slice;
 	}
 
 out:
-	/* we assume that ofs is aligned with 4 bytes */
+	/* xattrs should be 4-byte aligned (on-disk constraint) */
 	it->ofs = EROFS_XATTR_ALIGN(it->ofs);
-	return err;
+	return err < 0 ? err : 0;
 }
 
 struct getxattr_iter {
@@ -305,7 +329,7 @@ struct getxattr_iter {
 };
 
 static int xattr_entrymatch(struct xattr_iter *_it,
-	struct erofs_xattr_entry *entry)
+			    struct erofs_xattr_entry *entry)
 {
 	struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
 
@@ -314,7 +338,7 @@ static int xattr_entrymatch(struct xattr_iter *_it,
 }
 
 static int xattr_namematch(struct xattr_iter *_it,
-	unsigned processed, char *buf, unsigned len)
+			   unsigned int processed, char *buf, unsigned int len)
 {
 	struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
 
@@ -322,17 +346,18 @@ static int xattr_namematch(struct xattr_iter *_it,
 }
 
 static int xattr_checkbuffer(struct xattr_iter *_it,
-	unsigned value_sz)
+			     unsigned int value_sz)
 {
 	struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
 	int err = it->buffer_size < value_sz ? -ERANGE : 0;
 
 	it->buffer_size = value_sz;
-	return it->buffer == NULL ? 1 : err;
+	return !it->buffer ? 1 : err;
 }
 
 static void xattr_copyvalue(struct xattr_iter *_it,
-	unsigned processed, char *buf, unsigned len)
+			    unsigned int processed,
+			    char *buf, unsigned int len)
 {
 	struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
 
@@ -349,7 +374,7 @@ static const struct xattr_iter_handlers find_xattr_handlers = {
 static int inline_getxattr(struct inode *inode, struct getxattr_iter *it)
 {
 	int ret;
-	unsigned remaining;
+	unsigned int remaining;
 
 	ret = inline_xattr_iter_begin(&it->it, inode);
 	if (ret < 0)
@@ -358,22 +383,20 @@ static int inline_getxattr(struct inode *inode, struct getxattr_iter *it)
 	remaining = ret;
 	while (remaining) {
 		ret = xattr_foreach(&it->it, &find_xattr_handlers, &remaining);
-		if (ret >= 0)
-			break;
-
-		if (ret != -ENOATTR)	/* -ENOMEM, -EIO, etc. */
+		if (ret != -ENOATTR)
 			break;
 	}
 	xattr_iter_end_final(&it->it);
 
-	return ret < 0 ? ret : it->buffer_size;
+	return ret ? ret : it->buffer_size;
 }
 
 static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
 {
-	struct erofs_vnode *const vi = EROFS_V(inode);
-	struct erofs_sb_info *const sbi = EROFS_SB(inode->i_sb);
-	unsigned i;
+	struct erofs_inode *const vi = EROFS_I(inode);
+	struct super_block *const sb = inode->i_sb;
+	struct erofs_sb_info *const sbi = EROFS_SB(sb);
+	unsigned int i;
 	int ret = -ENOATTR;
 
 	for (i = 0; i < vi->xattr_shared_count; ++i) {
@@ -386,8 +409,7 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
 			if (i)
 				xattr_iter_end(&it->it, true);
 
-			it->it.page = erofs_get_meta_page(inode->i_sb,
-							  blkaddr, false);
+			it->it.page = erofs_get_meta_page(sb, blkaddr);
 			if (IS_ERR(it->it.page))
 				return PTR_ERR(it->it.page);
 
@@ -396,16 +418,13 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
 		}
 
 		ret = xattr_foreach(&it->it, &find_xattr_handlers, NULL);
-		if (ret >= 0)
-			break;
-
-		if (ret != -ENOATTR)	/* -ENOMEM, -EIO, etc. */
+		if (ret != -ENOATTR)
 			break;
 	}
 	if (vi->xattr_shared_count)
 		xattr_iter_end_final(&it->it);
 
-	return ret < 0 ? ret : it->buffer_size;
+	return ret ? ret : it->buffer_size;
 }
 
 static bool erofs_xattr_user_list(struct dentry *dentry)
@@ -419,13 +438,13 @@ static bool erofs_xattr_trusted_list(struct dentry *dentry)
 }
 
 int erofs_getxattr(struct inode *inode, int index,
-	const char *name,
-	void *buffer, size_t buffer_size)
+		   const char *name,
+		   void *buffer, size_t buffer_size)
 {
 	int ret;
 	struct getxattr_iter it;
 
-	if (unlikely(name == NULL))
+	if (!name)
 		return -EINVAL;
 
 	ret = init_inode_xattrs(inode);
@@ -450,8 +469,8 @@ int erofs_getxattr(struct inode *inode, int index,
 }
 
 static int erofs_xattr_generic_get(const struct xattr_handler *handler,
-		struct dentry *unused, struct inode *inode,
-		const char *name, void *buffer, size_t size)
+				   struct dentry *unused, struct inode *inode,
+				   const char *name, void *buffer, size_t size)
 {
 	struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
 
@@ -461,8 +480,6 @@ static int erofs_xattr_generic_get(const struct xattr_handler *handler,
 			return -EOPNOTSUPP;
 		break;
 	case EROFS_XATTR_INDEX_TRUSTED:
-		if (!capable(CAP_SYS_ADMIN))
-			return -EPERM;
 		break;
 	case EROFS_XATTR_INDEX_SECURITY:
 		break;
@@ -517,24 +534,23 @@ struct listxattr_iter {
 };
 
 static int xattr_entrylist(struct xattr_iter *_it,
-	struct erofs_xattr_entry *entry)
+			   struct erofs_xattr_entry *entry)
 {
 	struct listxattr_iter *it =
 		container_of(_it, struct listxattr_iter, it);
-	unsigned prefix_len;
+	unsigned int prefix_len;
 	const char *prefix;
 
 	const struct xattr_handler *h =
 		erofs_xattr_handler(entry->e_name_index);
 
-	if (h == NULL || (h->list != NULL && !h->list(it->dentry)))
+	if (!h || (h->list && !h->list(it->dentry)))
 		return 1;
 
-	/* Note that at least one of 'prefix' and 'name' should be non-NULL */
-	prefix = h->prefix != NULL ? h->prefix : h->name;
+	prefix = xattr_prefix(h);
 	prefix_len = strlen(prefix);
 
-	if (it->buffer == NULL) {
+	if (!it->buffer) {
 		it->buffer_ofs += prefix_len + entry->e_name_len + 1;
 		return 1;
 	}
@@ -549,7 +565,7 @@ static int xattr_entrylist(struct xattr_iter *_it,
 }
 
 static int xattr_namelist(struct xattr_iter *_it,
-	unsigned processed, char *buf, unsigned len)
+			  unsigned int processed, char *buf, unsigned int len)
 {
 	struct listxattr_iter *it =
 		container_of(_it, struct listxattr_iter, it);
@@ -560,7 +576,7 @@ static int xattr_namelist(struct xattr_iter *_it,
 }
 
 static int xattr_skipvalue(struct xattr_iter *_it,
-	unsigned value_sz)
+			   unsigned int value_sz)
 {
 	struct listxattr_iter *it =
 		container_of(_it, struct listxattr_iter, it);
@@ -579,7 +595,7 @@ static const struct xattr_iter_handlers list_xattr_handlers = {
 static int inline_listxattr(struct listxattr_iter *it)
 {
 	int ret;
-	unsigned remaining;
+	unsigned int remaining;
 
 	ret = inline_xattr_iter_begin(&it->it, d_inode(it->dentry));
 	if (ret < 0)
@@ -588,19 +604,20 @@ static int inline_listxattr(struct listxattr_iter *it)
 	remaining = ret;
 	while (remaining) {
 		ret = xattr_foreach(&it->it, &list_xattr_handlers, &remaining);
-		if (ret < 0)
+		if (ret)
 			break;
 	}
 	xattr_iter_end_final(&it->it);
-	return ret < 0 ? ret : it->buffer_ofs;
+	return ret ? ret : it->buffer_ofs;
 }
 
 static int shared_listxattr(struct listxattr_iter *it)
 {
 	struct inode *const inode = d_inode(it->dentry);
-	struct erofs_vnode *const vi = EROFS_V(inode);
-	struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
-	unsigned i;
+	struct erofs_inode *const vi = EROFS_I(inode);
+	struct super_block *const sb = inode->i_sb;
+	struct erofs_sb_info *const sbi = EROFS_SB(sb);
+	unsigned int i;
 	int ret = 0;
 
 	for (i = 0; i < vi->xattr_shared_count; ++i) {
@@ -612,8 +629,7 @@ static int shared_listxattr(struct listxattr_iter *it)
 			if (i)
 				xattr_iter_end(&it->it, true);
 
-			it->it.page = erofs_get_meta_page(inode->i_sb,
-							  blkaddr, false);
+			it->it.page = erofs_get_meta_page(sb, blkaddr);
 			if (IS_ERR(it->it.page))
 				return PTR_ERR(it->it.page);
 
@@ -622,17 +638,17 @@ static int shared_listxattr(struct listxattr_iter *it)
 		}
 
 		ret = xattr_foreach(&it->it, &list_xattr_handlers, NULL);
-		if (ret < 0)
+		if (ret)
 			break;
 	}
 	if (vi->xattr_shared_count)
 		xattr_iter_end_final(&it->it);
 
-	return ret < 0 ? ret : it->buffer_ofs;
+	return ret ? ret : it->buffer_ofs;
 }
 
 ssize_t erofs_listxattr(struct dentry *dentry,
-	char *buffer, size_t buffer_size)
+			char *buffer, size_t buffer_size)
 {
 	int ret;
 	struct listxattr_iter it;
@@ -656,3 +672,39 @@ ssize_t erofs_listxattr(struct dentry *dentry,
 	return shared_listxattr(&it);
 }
 
+#ifdef CONFIG_EROFS_FS_POSIX_ACL
+struct posix_acl *erofs_get_acl(struct inode *inode, int type)
+{
+	struct posix_acl *acl;
+	int prefix, rc;
+	char *value = NULL;
+
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		prefix = EROFS_XATTR_INDEX_POSIX_ACL_ACCESS;
+		break;
+	case ACL_TYPE_DEFAULT:
+		prefix = EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT;
+		break;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+
+	rc = erofs_getxattr(inode, prefix, "", NULL, 0);
+	if (rc > 0) {
+		value = kmalloc(rc, GFP_KERNEL);
+		if (!value)
+			return ERR_PTR(-ENOMEM);
+		rc = erofs_getxattr(inode, prefix, "", value, rc);
+	}
+
+	if (rc == -ENOATTR)
+		acl = NULL;
+	else if (rc < 0)
+		acl = ERR_PTR(rc);
+	else
+		acl = posix_acl_from_xattr(&init_user_ns, value, rc);
+	kfree(value);
+	return acl;
+}
+#endif
diff --git a/drivers/staging/erofs/xattr.h b/drivers/staging/erofs/xattr.h
index 0c7379282fc5..366dcb400525 100644
--- a/drivers/staging/erofs/xattr.h
+++ b/drivers/staging/erofs/xattr.h
@@ -1,14 +1,7 @@
-/* SPDX-License-Identifier: GPL-2.0
- *
- * linux/drivers/staging/erofs/xattr.h
- *
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
  * Copyright (C) 2017-2018 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
+ *             https://www.huawei.com/
  */
 #ifndef __EROFS_XATTR_H
 #define __EROFS_XATTR_H
@@ -20,14 +13,14 @@
 /* Attribute not found */
 #define ENOATTR         ENODATA
 
-static inline unsigned inlinexattr_header_size(struct inode *inode)
+static inline unsigned int inlinexattr_header_size(struct inode *inode)
 {
-	return sizeof(struct erofs_xattr_ibody_header)
-		+ sizeof(u32) * EROFS_V(inode)->xattr_shared_count;
+	return sizeof(struct erofs_xattr_ibody_header) +
+		sizeof(u32) * EROFS_I(inode)->xattr_shared_count;
 }
 
-static inline erofs_blk_t
-xattrblock_addr(struct erofs_sb_info *sbi, unsigned xattr_id)
+static inline erofs_blk_t xattrblock_addr(struct erofs_sb_info *sbi,
+					  unsigned int xattr_id)
 {
 #ifdef CONFIG_EROFS_FS_XATTR
 	return sbi->xattr_blkaddr +
@@ -37,56 +30,59 @@ xattrblock_addr(struct erofs_sb_info *sbi, unsigned xattr_id)
 #endif
 }
 
-static inline unsigned
-xattrblock_offset(struct erofs_sb_info *sbi, unsigned xattr_id)
+static inline unsigned int xattrblock_offset(struct erofs_sb_info *sbi,
+					     unsigned int xattr_id)
 {
 	return (xattr_id * sizeof(__u32)) % EROFS_BLKSIZ;
 }
 
+#ifdef CONFIG_EROFS_FS_XATTR
 extern const struct xattr_handler erofs_xattr_user_handler;
 extern const struct xattr_handler erofs_xattr_trusted_handler;
 #ifdef CONFIG_EROFS_FS_SECURITY
 extern const struct xattr_handler erofs_xattr_security_handler;
 #endif
 
-static inline const struct xattr_handler *erofs_xattr_handler(unsigned index)
+static inline const struct xattr_handler *erofs_xattr_handler(unsigned int idx)
 {
-static const struct xattr_handler *xattr_handler_map[] = {
-	[EROFS_XATTR_INDEX_USER] = &erofs_xattr_user_handler,
+	static const struct xattr_handler *xattr_handler_map[] = {
+		[EROFS_XATTR_INDEX_USER] = &erofs_xattr_user_handler,
 #ifdef CONFIG_EROFS_FS_POSIX_ACL
-	[EROFS_XATTR_INDEX_POSIX_ACL_ACCESS] = &posix_acl_access_xattr_handler,
-	[EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT] =
-		&posix_acl_default_xattr_handler,
+		[EROFS_XATTR_INDEX_POSIX_ACL_ACCESS] =
+			&posix_acl_access_xattr_handler,
+		[EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT] =
+			&posix_acl_default_xattr_handler,
 #endif
-	[EROFS_XATTR_INDEX_TRUSTED] = &erofs_xattr_trusted_handler,
+		[EROFS_XATTR_INDEX_TRUSTED] = &erofs_xattr_trusted_handler,
 #ifdef CONFIG_EROFS_FS_SECURITY
-	[EROFS_XATTR_INDEX_SECURITY] = &erofs_xattr_security_handler,
+		[EROFS_XATTR_INDEX_SECURITY] = &erofs_xattr_security_handler,
 #endif
-};
-	return index && index < ARRAY_SIZE(xattr_handler_map) ?
-		xattr_handler_map[index] : NULL;
-}
+	};
 
-#ifdef CONFIG_EROFS_FS_XATTR
+	return idx && idx < ARRAY_SIZE(xattr_handler_map) ?
+		xattr_handler_map[idx] : NULL;
+}
 
-extern const struct inode_operations erofs_generic_xattr_iops;
-extern const struct inode_operations erofs_dir_xattr_iops;
+extern const struct xattr_handler *erofs_xattr_handlers[];
 
 int erofs_getxattr(struct inode *, int, const char *, void *, size_t);
 ssize_t erofs_listxattr(struct dentry *, char *, size_t);
 #else
-static int __maybe_unused erofs_getxattr(struct inode *inode, int index,
-	const char *name,
-	void *buffer, size_t buffer_size)
+static inline int erofs_getxattr(struct inode *inode, int index,
+				 const char *name, void *buffer,
+				 size_t buffer_size)
 {
-	return -ENOTSUPP;
+	return -EOPNOTSUPP;
 }
 
-static ssize_t __maybe_unused erofs_listxattr(struct dentry *dentry,
-	char *buffer, size_t buffer_size)
-{
-	return -ENOTSUPP;
-}
+#define erofs_listxattr (NULL)
+#define erofs_xattr_handlers (NULL)
+#endif	/* !CONFIG_EROFS_FS_XATTR */
+
+#ifdef CONFIG_EROFS_FS_POSIX_ACL
+struct posix_acl *erofs_get_acl(struct inode *inode, int type);
+#else
+#define erofs_get_acl	(NULL)
 #endif
 
 #endif
diff --git a/drivers/staging/erofs/zdata.c b/drivers/staging/erofs/zdata.c
new file mode 100644
index 000000000000..37c3e28b1e91
--- /dev/null
+++ b/drivers/staging/erofs/zdata.c
@@ -0,0 +1,1370 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2018 HUAWEI, Inc.
+ *             https://www.huawei.com/
+ */
+#include "zdata.h"
+#include "compress.h"
+#include <linux/prefetch.h>
+
+#include <trace/events/erofs.h>
+
+/*
+ * a compressed_pages[] placeholder in order to avoid
+ * being filled with file pages for in-place decompression.
+ */
+#define PAGE_UNALLOCATED     ((void *)0x5F0E4B1D)
+
+/* how to allocate cached pages for a pcluster */
+enum z_erofs_cache_alloctype {
+	DONTALLOC,	/* don't allocate any cached pages */
+	DELAYEDALLOC,	/* delayed allocation (at the time of submitting io) */
+};
+
+/*
+ * tagged pointer with 1-bit tag for all compressed pages
+ * tag 0 - the page is just found with an extra page reference
+ */
+typedef tagptr1_t compressed_page_t;
+
+#define tag_compressed_page_justfound(page) \
+	tagptr_fold(compressed_page_t, page, 1)
+
+static struct workqueue_struct *z_erofs_workqueue __read_mostly;
+static struct kmem_cache *pcluster_cachep __read_mostly;
+
+void z_erofs_exit_zip_subsystem(void)
+{
+	destroy_workqueue(z_erofs_workqueue);
+	kmem_cache_destroy(pcluster_cachep);
+}
+
+static inline int z_erofs_init_workqueue(void)
+{
+	const unsigned int onlinecpus = num_possible_cpus();
+
+	/*
+	 * no need to spawn too many threads, limiting threads could minimum
+	 * scheduling overhead, perhaps per-CPU threads should be better?
+	 */
+	z_erofs_workqueue = alloc_workqueue("erofs_unzipd",
+					    WQ_UNBOUND | WQ_HIGHPRI,
+					    onlinecpus + onlinecpus / 4);
+	return z_erofs_workqueue ? 0 : -ENOMEM;
+}
+
+static void z_erofs_pcluster_init_once(void *ptr)
+{
+	struct z_erofs_pcluster *pcl = ptr;
+	struct z_erofs_collection *cl = z_erofs_primarycollection(pcl);
+	unsigned int i;
+
+	mutex_init(&cl->lock);
+	cl->nr_pages = 0;
+	cl->vcnt = 0;
+	for (i = 0; i < Z_EROFS_CLUSTER_MAX_PAGES; ++i)
+		pcl->compressed_pages[i] = NULL;
+}
+
+static void z_erofs_pcluster_init_always(struct z_erofs_pcluster *pcl)
+{
+	struct z_erofs_collection *cl = z_erofs_primarycollection(pcl);
+
+	atomic_set(&pcl->obj.refcount, 1);
+
+	DBG_BUGON(cl->nr_pages);
+	DBG_BUGON(cl->vcnt);
+}
+
+int __init z_erofs_init_zip_subsystem(void)
+{
+	pcluster_cachep = kmem_cache_create("erofs_compress",
+					    Z_EROFS_WORKGROUP_SIZE, 0,
+					    SLAB_RECLAIM_ACCOUNT,
+					    z_erofs_pcluster_init_once);
+	if (pcluster_cachep) {
+		if (!z_erofs_init_workqueue())
+			return 0;
+
+		kmem_cache_destroy(pcluster_cachep);
+	}
+	return -ENOMEM;
+}
+
+enum z_erofs_collectmode {
+	COLLECT_SECONDARY,
+	COLLECT_PRIMARY,
+	/*
+	 * The current collection was the tail of an exist chain, in addition
+	 * that the previous processed chained collections are all decided to
+	 * be hooked up to it.
+	 * A new chain will be created for the remaining collections which are
+	 * not processed yet, therefore different from COLLECT_PRIMARY_FOLLOWED,
+	 * the next collection cannot reuse the whole page safely in
+	 * the following scenario:
+	 *  ________________________________________________________________
+	 * |      tail (partial) page     |       head (partial) page       |
+	 * |   (belongs to the next cl)   |   (belongs to the current cl)   |
+	 * |_______PRIMARY_FOLLOWED_______|________PRIMARY_HOOKED___________|
+	 */
+	COLLECT_PRIMARY_HOOKED,
+	COLLECT_PRIMARY_FOLLOWED_NOINPLACE,
+	/*
+	 * The current collection has been linked with the owned chain, and
+	 * could also be linked with the remaining collections, which means
+	 * if the processing page is the tail page of the collection, thus
+	 * the current collection can safely use the whole page (since
+	 * the previous collection is under control) for in-place I/O, as
+	 * illustrated below:
+	 *  ________________________________________________________________
+	 * |  tail (partial) page |          head (partial) page           |
+	 * |  (of the current cl) |      (of the previous collection)      |
+	 * |  PRIMARY_FOLLOWED or |                                        |
+	 * |_____PRIMARY_HOOKED___|____________PRIMARY_FOLLOWED____________|
+	 *
+	 * [  (*) the above page can be used as inplace I/O.               ]
+	 */
+	COLLECT_PRIMARY_FOLLOWED,
+};
+
+struct z_erofs_collector {
+	struct z_erofs_pagevec_ctor vector;
+
+	struct z_erofs_pcluster *pcl, *tailpcl;
+	struct z_erofs_collection *cl;
+	struct page **compressedpages;
+	z_erofs_next_pcluster_t owned_head;
+
+	enum z_erofs_collectmode mode;
+};
+
+struct z_erofs_decompress_frontend {
+	struct inode *const inode;
+
+	struct z_erofs_collector clt;
+	struct erofs_map_blocks map;
+
+	bool readahead;
+	/* used for applying cache strategy on the fly */
+	bool backmost;
+	erofs_off_t headoffset;
+};
+
+#define COLLECTOR_INIT() { \
+	.owned_head = Z_EROFS_PCLUSTER_TAIL, \
+	.mode = COLLECT_PRIMARY_FOLLOWED }
+
+#define DECOMPRESS_FRONTEND_INIT(__i) { \
+	.inode = __i, .clt = COLLECTOR_INIT(), \
+	.backmost = true, }
+
+static struct page *z_pagemap_global[Z_EROFS_VMAP_GLOBAL_PAGES];
+static DEFINE_MUTEX(z_pagemap_global_lock);
+
+static void preload_compressed_pages(struct z_erofs_collector *clt,
+				     struct address_space *mc,
+				     enum z_erofs_cache_alloctype type)
+{
+	const struct z_erofs_pcluster *pcl = clt->pcl;
+	const unsigned int clusterpages = BIT(pcl->clusterbits);
+	struct page **pages = clt->compressedpages;
+	pgoff_t index = pcl->obj.index + (pages - pcl->compressed_pages);
+	bool standalone = true;
+
+	if (clt->mode < COLLECT_PRIMARY_FOLLOWED)
+		return;
+
+	for (; pages < pcl->compressed_pages + clusterpages; ++pages) {
+		struct page *page;
+		compressed_page_t t;
+
+		/* the compressed page was loaded before */
+		if (READ_ONCE(*pages))
+			continue;
+
+		page = find_get_page(mc, index);
+
+		if (page) {
+			t = tag_compressed_page_justfound(page);
+		} else if (type == DELAYEDALLOC) {
+			t = tagptr_init(compressed_page_t, PAGE_UNALLOCATED);
+		} else {	/* DONTALLOC */
+			if (standalone)
+				clt->compressedpages = pages;
+			standalone = false;
+			continue;
+		}
+
+		if (!cmpxchg_relaxed(pages, NULL, tagptr_cast_ptr(t)))
+			continue;
+
+		if (page)
+			put_page(page);
+	}
+
+	if (standalone)		/* downgrade to PRIMARY_FOLLOWED_NOINPLACE */
+		clt->mode = COLLECT_PRIMARY_FOLLOWED_NOINPLACE;
+}
+
+/* called by erofs_shrinker to get rid of all compressed_pages */
+int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
+				       struct erofs_workgroup *grp)
+{
+	struct z_erofs_pcluster *const pcl =
+		container_of(grp, struct z_erofs_pcluster, obj);
+	struct address_space *const mapping = MNGD_MAPPING(sbi);
+	const unsigned int clusterpages = BIT(pcl->clusterbits);
+	int i;
+
+	/*
+	 * refcount of workgroup is now freezed as 1,
+	 * therefore no need to worry about available decompression users.
+	 */
+	for (i = 0; i < clusterpages; ++i) {
+		struct page *page = pcl->compressed_pages[i];
+
+		if (!page)
+			continue;
+
+		/* block other users from reclaiming or migrating the page */
+		if (!trylock_page(page))
+			return -EBUSY;
+
+		if (page->mapping != mapping)
+			continue;
+
+		/* barrier is implied in the following 'unlock_page' */
+		WRITE_ONCE(pcl->compressed_pages[i], NULL);
+		set_page_private(page, 0);
+		ClearPagePrivate(page);
+
+		unlock_page(page);
+		put_page(page);
+	}
+	return 0;
+}
+
+int erofs_try_to_free_cached_page(struct address_space *mapping,
+				  struct page *page)
+{
+	struct z_erofs_pcluster *const pcl = (void *)page_private(page);
+	const unsigned int clusterpages = BIT(pcl->clusterbits);
+	int ret = 0;	/* 0 - busy */
+
+	if (erofs_workgroup_try_to_freeze(&pcl->obj, 1)) {
+		unsigned int i;
+
+		for (i = 0; i < clusterpages; ++i) {
+			if (pcl->compressed_pages[i] == page) {
+				WRITE_ONCE(pcl->compressed_pages[i], NULL);
+				ret = 1;
+				break;
+			}
+		}
+		erofs_workgroup_unfreeze(&pcl->obj, 1);
+
+		if (ret) {
+			ClearPagePrivate(page);
+			put_page(page);
+		}
+	}
+	return ret;
+}
+
+/* page_type must be Z_EROFS_PAGE_TYPE_EXCLUSIVE */
+static inline bool z_erofs_try_inplace_io(struct z_erofs_collector *clt,
+					  struct page *page)
+{
+	struct z_erofs_pcluster *const pcl = clt->pcl;
+	const unsigned int clusterpages = BIT(pcl->clusterbits);
+
+	while (clt->compressedpages < pcl->compressed_pages + clusterpages) {
+		if (!cmpxchg(clt->compressedpages++, NULL, page))
+			return true;
+	}
+	return false;
+}
+
+/* callers must be with collection lock held */
+static int z_erofs_attach_page(struct z_erofs_collector *clt,
+			       struct page *page,
+			       enum z_erofs_page_type type)
+{
+	int ret;
+	bool occupied;
+
+	/* give priority for inplaceio */
+	if (clt->mode >= COLLECT_PRIMARY &&
+	    type == Z_EROFS_PAGE_TYPE_EXCLUSIVE &&
+	    z_erofs_try_inplace_io(clt, page))
+		return 0;
+
+	ret = z_erofs_pagevec_enqueue(&clt->vector,
+				      page, type, &occupied);
+	clt->cl->vcnt += (unsigned int)ret;
+
+	return ret ? 0 : -EAGAIN;
+}
+
+static enum z_erofs_collectmode
+try_to_claim_pcluster(struct z_erofs_pcluster *pcl,
+		      z_erofs_next_pcluster_t *owned_head)
+{
+	/* let's claim these following types of pclusters */
+retry:
+	if (pcl->next == Z_EROFS_PCLUSTER_NIL) {
+		/* type 1, nil pcluster */
+		if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_NIL,
+			    *owned_head) != Z_EROFS_PCLUSTER_NIL)
+			goto retry;
+
+		*owned_head = &pcl->next;
+		/* lucky, I am the followee :) */
+		return COLLECT_PRIMARY_FOLLOWED;
+	} else if (pcl->next == Z_EROFS_PCLUSTER_TAIL) {
+		/*
+		 * type 2, link to the end of a existing open chain,
+		 * be careful that its submission itself is governed
+		 * by the original owned chain.
+		 */
+		if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
+			    *owned_head) != Z_EROFS_PCLUSTER_TAIL)
+			goto retry;
+		*owned_head = Z_EROFS_PCLUSTER_TAIL;
+		return COLLECT_PRIMARY_HOOKED;
+	}
+	return COLLECT_PRIMARY;	/* :( better luck next time */
+}
+
+static int z_erofs_lookup_collection(struct z_erofs_collector *clt,
+				     struct inode *inode,
+				     struct erofs_map_blocks *map)
+{
+	struct erofs_workgroup *grp;
+	struct z_erofs_pcluster *pcl;
+	struct z_erofs_collection *cl;
+	unsigned int length;
+
+	grp = erofs_find_workgroup(inode->i_sb, map->m_pa >> PAGE_SHIFT);
+	if (!grp)
+		return -ENOENT;
+
+	pcl = container_of(grp, struct z_erofs_pcluster, obj);
+	if (clt->owned_head == &pcl->next || pcl == clt->tailpcl) {
+		DBG_BUGON(1);
+		erofs_workgroup_put(grp);
+		return -EFSCORRUPTED;
+	}
+
+	cl = z_erofs_primarycollection(pcl);
+	if (cl->pageofs != (map->m_la & ~PAGE_MASK)) {
+		DBG_BUGON(1);
+		erofs_workgroup_put(grp);
+		return -EFSCORRUPTED;
+	}
+
+	length = READ_ONCE(pcl->length);
+	if (length & Z_EROFS_PCLUSTER_FULL_LENGTH) {
+		if ((map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) > length) {
+			DBG_BUGON(1);
+			erofs_workgroup_put(grp);
+			return -EFSCORRUPTED;
+		}
+	} else {
+		unsigned int llen = map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT;
+
+		if (map->m_flags & EROFS_MAP_FULL_MAPPED)
+			llen |= Z_EROFS_PCLUSTER_FULL_LENGTH;
+
+		while (llen > length &&
+		       length != cmpxchg_relaxed(&pcl->length, length, llen)) {
+			cpu_relax();
+			length = READ_ONCE(pcl->length);
+		}
+	}
+	mutex_lock(&cl->lock);
+	/* used to check tail merging loop due to corrupted images */
+	if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
+		clt->tailpcl = pcl;
+	clt->mode = try_to_claim_pcluster(pcl, &clt->owned_head);
+	/* clean tailpcl if the current owned_head is Z_EROFS_PCLUSTER_TAIL */
+	if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
+		clt->tailpcl = NULL;
+	clt->pcl = pcl;
+	clt->cl = cl;
+	return 0;
+}
+
+static int z_erofs_register_collection(struct z_erofs_collector *clt,
+				       struct inode *inode,
+				       struct erofs_map_blocks *map)
+{
+	struct z_erofs_pcluster *pcl;
+	struct z_erofs_collection *cl;
+	int err;
+
+	/* no available workgroup, let's allocate one */
+	pcl = kmem_cache_alloc(pcluster_cachep, GFP_NOFS);
+	if (!pcl)
+		return -ENOMEM;
+
+	z_erofs_pcluster_init_always(pcl);
+	pcl->obj.index = map->m_pa >> PAGE_SHIFT;
+
+	pcl->length = (map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) |
+		(map->m_flags & EROFS_MAP_FULL_MAPPED ?
+			Z_EROFS_PCLUSTER_FULL_LENGTH : 0);
+
+	if (map->m_flags & EROFS_MAP_ZIPPED)
+		pcl->algorithmformat = Z_EROFS_COMPRESSION_LZ4;
+	else
+		pcl->algorithmformat = Z_EROFS_COMPRESSION_SHIFTED;
+
+	pcl->clusterbits = EROFS_I(inode)->z_physical_clusterbits[0];
+	pcl->clusterbits -= PAGE_SHIFT;
+
+	/* new pclusters should be claimed as type 1, primary and followed */
+	pcl->next = clt->owned_head;
+	clt->mode = COLLECT_PRIMARY_FOLLOWED;
+
+	cl = z_erofs_primarycollection(pcl);
+	cl->pageofs = map->m_la & ~PAGE_MASK;
+
+	/*
+	 * lock all primary followed works before visible to others
+	 * and mutex_trylock *never* fails for a new pcluster.
+	 */
+	mutex_trylock(&cl->lock);
+
+	err = erofs_register_workgroup(inode->i_sb, &pcl->obj);
+	if (err) {
+		mutex_unlock(&cl->lock);
+		kmem_cache_free(pcluster_cachep, pcl);
+		return -EAGAIN;
+	}
+	/* used to check tail merging loop due to corrupted images */
+	if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
+		clt->tailpcl = pcl;
+	clt->owned_head = &pcl->next;
+	clt->pcl = pcl;
+	clt->cl = cl;
+	return 0;
+}
+
+static int z_erofs_collector_begin(struct z_erofs_collector *clt,
+				   struct inode *inode,
+				   struct erofs_map_blocks *map)
+{
+	int ret;
+
+	DBG_BUGON(clt->cl);
+
+	/* must be Z_EROFS_PCLUSTER_TAIL or pointed to previous collection */
+	DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_NIL);
+	DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
+
+	if (!PAGE_ALIGNED(map->m_pa)) {
+		DBG_BUGON(1);
+		return -EINVAL;
+	}
+
+repeat:
+	ret = z_erofs_lookup_collection(clt, inode, map);
+	if (ret == -ENOENT) {
+		ret = z_erofs_register_collection(clt, inode, map);
+
+		/* someone registered at the same time, give another try */
+		if (ret == -EAGAIN) {
+			cond_resched();
+			goto repeat;
+		}
+	}
+
+	if (ret)
+		return ret;
+
+	z_erofs_pagevec_ctor_init(&clt->vector, Z_EROFS_NR_INLINE_PAGEVECS,
+				  clt->cl->pagevec, clt->cl->vcnt);
+
+	clt->compressedpages = clt->pcl->compressed_pages;
+	if (clt->mode <= COLLECT_PRIMARY) /* cannot do in-place I/O */
+		clt->compressedpages += Z_EROFS_CLUSTER_MAX_PAGES;
+	return 0;
+}
+
+/*
+ * keep in mind that no referenced pclusters will be freed
+ * only after a RCU grace period.
+ */
+static void z_erofs_rcu_callback(struct rcu_head *head)
+{
+	struct z_erofs_collection *const cl =
+		container_of(head, struct z_erofs_collection, rcu);
+
+	kmem_cache_free(pcluster_cachep,
+			container_of(cl, struct z_erofs_pcluster,
+				     primary_collection));
+}
+
+void erofs_workgroup_free_rcu(struct erofs_workgroup *grp)
+{
+	struct z_erofs_pcluster *const pcl =
+		container_of(grp, struct z_erofs_pcluster, obj);
+	struct z_erofs_collection *const cl = z_erofs_primarycollection(pcl);
+
+	call_rcu(&cl->rcu, z_erofs_rcu_callback);
+}
+
+static void z_erofs_collection_put(struct z_erofs_collection *cl)
+{
+	struct z_erofs_pcluster *const pcl =
+		container_of(cl, struct z_erofs_pcluster, primary_collection);
+
+	erofs_workgroup_put(&pcl->obj);
+}
+
+static bool z_erofs_collector_end(struct z_erofs_collector *clt)
+{
+	struct z_erofs_collection *cl = clt->cl;
+
+	if (!cl)
+		return false;
+
+	z_erofs_pagevec_ctor_exit(&clt->vector, false);
+	mutex_unlock(&cl->lock);
+
+	/*
+	 * if all pending pages are added, don't hold its reference
+	 * any longer if the pcluster isn't hosted by ourselves.
+	 */
+	if (clt->mode < COLLECT_PRIMARY_FOLLOWED_NOINPLACE)
+		z_erofs_collection_put(cl);
+
+	clt->cl = NULL;
+	return true;
+}
+
+static bool should_alloc_managed_pages(struct z_erofs_decompress_frontend *fe,
+				       unsigned int cachestrategy,
+				       erofs_off_t la)
+{
+	if (cachestrategy <= EROFS_ZIP_CACHE_DISABLED)
+		return false;
+
+	if (fe->backmost)
+		return true;
+
+	return cachestrategy >= EROFS_ZIP_CACHE_READAROUND &&
+		la < fe->headoffset;
+}
+
+static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
+				struct page *page)
+{
+	struct inode *const inode = fe->inode;
+	struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
+	struct erofs_map_blocks *const map = &fe->map;
+	struct z_erofs_collector *const clt = &fe->clt;
+	const loff_t offset = page_offset(page);
+	bool tight = true;
+
+	enum z_erofs_cache_alloctype cache_strategy;
+	enum z_erofs_page_type page_type;
+	unsigned int cur, end, spiltted, index;
+	int err = 0;
+
+	/* register locked file pages as online pages in pack */
+	z_erofs_onlinepage_init(page);
+
+	spiltted = 0;
+	end = PAGE_SIZE;
+repeat:
+	cur = end - 1;
+
+	/* lucky, within the range of the current map_blocks */
+	if (offset + cur >= map->m_la &&
+	    offset + cur < map->m_la + map->m_llen) {
+		/* didn't get a valid collection previously (very rare) */
+		if (!clt->cl)
+			goto restart_now;
+		goto hitted;
+	}
+
+	/* go ahead the next map_blocks */
+	erofs_dbg("%s: [out-of-range] pos %llu", __func__, offset + cur);
+
+	if (z_erofs_collector_end(clt))
+		fe->backmost = false;
+
+	map->m_la = offset + cur;
+	map->m_llen = 0;
+	err = z_erofs_map_blocks_iter(inode, map, 0);
+	if (err)
+		goto err_out;
+
+restart_now:
+	if (!(map->m_flags & EROFS_MAP_MAPPED))
+		goto hitted;
+
+	err = z_erofs_collector_begin(clt, inode, map);
+	if (err)
+		goto err_out;
+
+	/* preload all compressed pages (maybe downgrade role if necessary) */
+	if (should_alloc_managed_pages(fe, sbi->cache_strategy, map->m_la))
+		cache_strategy = DELAYEDALLOC;
+	else
+		cache_strategy = DONTALLOC;
+
+	preload_compressed_pages(clt, MNGD_MAPPING(sbi), cache_strategy);
+
+hitted:
+	/*
+	 * Ensure the current partial page belongs to this submit chain rather
+	 * than other concurrent submit chains or the noio(bypass) chain since
+	 * those chains are handled asynchronously thus the page cannot be used
+	 * for inplace I/O or pagevec (should be processed in strict order.)
+	 */
+	tight &= (clt->mode >= COLLECT_PRIMARY_HOOKED &&
+		  clt->mode != COLLECT_PRIMARY_FOLLOWED_NOINPLACE);
+
+	cur = end - min_t(unsigned int, offset + end - map->m_la, end);
+	if (!(map->m_flags & EROFS_MAP_MAPPED)) {
+		zero_user_segment(page, cur, end);
+		goto next_part;
+	}
+
+	/* let's derive page type */
+	page_type = cur ? Z_EROFS_VLE_PAGE_TYPE_HEAD :
+		(!spiltted ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
+			(tight ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
+				Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED));
+
+	if (cur)
+		tight &= (clt->mode >= COLLECT_PRIMARY_FOLLOWED);
+
+retry:
+	err = z_erofs_attach_page(clt, page, page_type);
+	/* should allocate an additional staging page for pagevec */
+	if (err == -EAGAIN) {
+		struct page *const newpage =
+				alloc_page(GFP_NOFS | __GFP_NOFAIL);
+
+		newpage->mapping = Z_EROFS_MAPPING_STAGING;
+		err = z_erofs_attach_page(clt, newpage,
+					  Z_EROFS_PAGE_TYPE_EXCLUSIVE);
+		if (!err)
+			goto retry;
+	}
+
+	if (err)
+		goto err_out;
+
+	index = page->index - (map->m_la >> PAGE_SHIFT);
+
+	z_erofs_onlinepage_fixup(page, index, true);
+
+	/* bump up the number of spiltted parts of a page */
+	++spiltted;
+	/* also update nr_pages */
+	clt->cl->nr_pages = max_t(pgoff_t, clt->cl->nr_pages, index + 1);
+next_part:
+	/* can be used for verification */
+	map->m_llen = offset + cur - map->m_la;
+
+	end = cur;
+	if (end > 0)
+		goto repeat;
+
+out:
+	z_erofs_onlinepage_endio(page);
+
+	erofs_dbg("%s, finish page: %pK spiltted: %u map->m_llen %llu",
+		  __func__, page, spiltted, map->m_llen);
+	return err;
+
+	/* if some error occurred while processing this page */
+err_out:
+	SetPageError(page);
+	goto out;
+}
+
+static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
+				       bool sync, int bios)
+{
+	/* wake up the caller thread for sync decompression */
+	if (sync) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&io->u.wait.lock, flags);
+		if (!atomic_add_return(bios, &io->pending_bios))
+			wake_up_locked(&io->u.wait);
+		spin_unlock_irqrestore(&io->u.wait.lock, flags);
+		return;
+	}
+
+	if (!atomic_add_return(bios, &io->pending_bios))
+		queue_work(z_erofs_workqueue, &io->u.work);
+}
+
+static void z_erofs_decompressqueue_endio(struct bio *bio)
+{
+	tagptr1_t t = tagptr_init(tagptr1_t, bio->bi_private);
+	struct z_erofs_decompressqueue *q = tagptr_unfold_ptr(t);
+	blk_status_t err = bio->bi_status;
+	struct bio_vec *bvec;
+	unsigned int i;
+
+	bio_for_each_segment_all(bvec, bio, i) {
+		struct page *page = bvec->bv_page;
+
+		DBG_BUGON(PageUptodate(page));
+		DBG_BUGON(!page->mapping);
+
+		if (err)
+			SetPageError(page);
+
+		if (erofs_page_is_managed(EROFS_SB(q->sb), page)) {
+			if (!err)
+				SetPageUptodate(page);
+			unlock_page(page);
+		}
+	}
+	z_erofs_decompress_kickoff(q, tagptr_unfold_tags(t), -1);
+	bio_put(bio);
+}
+
+static int z_erofs_decompress_pcluster(struct super_block *sb,
+				       struct z_erofs_pcluster *pcl,
+				       struct list_head *pagepool)
+{
+	struct erofs_sb_info *const sbi = EROFS_SB(sb);
+	const unsigned int clusterpages = BIT(pcl->clusterbits);
+	struct z_erofs_pagevec_ctor ctor;
+	unsigned int i, outputsize, llen, nr_pages;
+	struct page *pages_onstack[Z_EROFS_VMAP_ONSTACK_PAGES];
+	struct page **pages, **compressed_pages, *page;
+
+	enum z_erofs_page_type page_type;
+	bool overlapped, partial;
+	struct z_erofs_collection *cl;
+	int err;
+
+	might_sleep();
+	cl = z_erofs_primarycollection(pcl);
+	DBG_BUGON(!READ_ONCE(cl->nr_pages));
+
+	mutex_lock(&cl->lock);
+	nr_pages = cl->nr_pages;
+
+	if (nr_pages <= Z_EROFS_VMAP_ONSTACK_PAGES) {
+		pages = pages_onstack;
+	} else if (nr_pages <= Z_EROFS_VMAP_GLOBAL_PAGES &&
+		   mutex_trylock(&z_pagemap_global_lock)) {
+		pages = z_pagemap_global;
+	} else {
+		gfp_t gfp_flags = GFP_KERNEL;
+
+		if (nr_pages > Z_EROFS_VMAP_GLOBAL_PAGES)
+			gfp_flags |= __GFP_NOFAIL;
+
+		pages = kvmalloc_array(nr_pages, sizeof(struct page *),
+				       gfp_flags);
+
+		/* fallback to global pagemap for the lowmem scenario */
+		if (!pages) {
+			mutex_lock(&z_pagemap_global_lock);
+			pages = z_pagemap_global;
+		}
+	}
+
+	for (i = 0; i < nr_pages; ++i)
+		pages[i] = NULL;
+
+	err = 0;
+	z_erofs_pagevec_ctor_init(&ctor, Z_EROFS_NR_INLINE_PAGEVECS,
+				  cl->pagevec, 0);
+
+	for (i = 0; i < cl->vcnt; ++i) {
+		unsigned int pagenr;
+
+		page = z_erofs_pagevec_dequeue(&ctor, &page_type);
+
+		/* all pages in pagevec ought to be valid */
+		DBG_BUGON(!page);
+		DBG_BUGON(!page->mapping);
+
+		if (z_erofs_put_stagingpage(pagepool, page))
+			continue;
+
+		if (page_type == Z_EROFS_VLE_PAGE_TYPE_HEAD)
+			pagenr = 0;
+		else
+			pagenr = z_erofs_onlinepage_index(page);
+
+		DBG_BUGON(pagenr >= nr_pages);
+
+		/*
+		 * currently EROFS doesn't support multiref(dedup),
+		 * so here erroring out one multiref page.
+		 */
+		if (pages[pagenr]) {
+			DBG_BUGON(1);
+			SetPageError(pages[pagenr]);
+			z_erofs_onlinepage_endio(pages[pagenr]);
+			err = -EFSCORRUPTED;
+		}
+		pages[pagenr] = page;
+	}
+	z_erofs_pagevec_ctor_exit(&ctor, true);
+
+	overlapped = false;
+	compressed_pages = pcl->compressed_pages;
+
+	for (i = 0; i < clusterpages; ++i) {
+		unsigned int pagenr;
+
+		page = compressed_pages[i];
+
+		/* all compressed pages ought to be valid */
+		DBG_BUGON(!page);
+		DBG_BUGON(!page->mapping);
+
+		if (!z_erofs_page_is_staging(page)) {
+			if (erofs_page_is_managed(sbi, page)) {
+				if (!PageUptodate(page))
+					err = -EIO;
+				continue;
+			}
+
+			/*
+			 * only if non-head page can be selected
+			 * for inplace decompression
+			 */
+			pagenr = z_erofs_onlinepage_index(page);
+
+			DBG_BUGON(pagenr >= nr_pages);
+			if (pages[pagenr]) {
+				DBG_BUGON(1);
+				SetPageError(pages[pagenr]);
+				z_erofs_onlinepage_endio(pages[pagenr]);
+				err = -EFSCORRUPTED;
+			}
+			pages[pagenr] = page;
+
+			overlapped = true;
+		}
+
+		/* PG_error needs checking for inplaced and staging pages */
+		if (PageError(page)) {
+			DBG_BUGON(PageUptodate(page));
+			err = -EIO;
+		}
+	}
+
+	if (err)
+		goto out;
+
+	llen = pcl->length >> Z_EROFS_PCLUSTER_LENGTH_BIT;
+	if (nr_pages << PAGE_SHIFT >= cl->pageofs + llen) {
+		outputsize = llen;
+		partial = !(pcl->length & Z_EROFS_PCLUSTER_FULL_LENGTH);
+	} else {
+		outputsize = (nr_pages << PAGE_SHIFT) - cl->pageofs;
+		partial = true;
+	}
+
+	err = z_erofs_decompress(&(struct z_erofs_decompress_req) {
+					.sb = sb,
+					.in = compressed_pages,
+					.out = pages,
+					.pageofs_out = cl->pageofs,
+					.inputsize = PAGE_SIZE,
+					.outputsize = outputsize,
+					.alg = pcl->algorithmformat,
+					.inplace_io = overlapped,
+					.partial_decoding = partial
+				 }, pagepool);
+
+out:
+	/* must handle all compressed pages before endding pages */
+	for (i = 0; i < clusterpages; ++i) {
+		page = compressed_pages[i];
+
+		if (erofs_page_is_managed(sbi, page))
+			continue;
+
+		/* recycle all individual staging pages */
+		(void)z_erofs_put_stagingpage(pagepool, page);
+
+		WRITE_ONCE(compressed_pages[i], NULL);
+	}
+
+	for (i = 0; i < nr_pages; ++i) {
+		page = pages[i];
+		if (!page)
+			continue;
+
+		DBG_BUGON(!page->mapping);
+
+		/* recycle all individual staging pages */
+		if (z_erofs_put_stagingpage(pagepool, page))
+			continue;
+
+		if (err < 0)
+			SetPageError(page);
+
+		z_erofs_onlinepage_endio(page);
+	}
+
+	if (pages == z_pagemap_global)
+		mutex_unlock(&z_pagemap_global_lock);
+	else if (pages != pages_onstack)
+		kvfree(pages);
+
+	cl->nr_pages = 0;
+	cl->vcnt = 0;
+
+	/* all cl locks MUST be taken before the following line */
+	WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_NIL);
+
+	/* all cl locks SHOULD be released right now */
+	mutex_unlock(&cl->lock);
+
+	z_erofs_collection_put(cl);
+	return err;
+}
+
+static void z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,
+				     struct list_head *pagepool)
+{
+	z_erofs_next_pcluster_t owned = io->head;
+
+	while (owned != Z_EROFS_PCLUSTER_TAIL_CLOSED) {
+		struct z_erofs_pcluster *pcl;
+
+		/* no possible that 'owned' equals Z_EROFS_WORK_TPTR_TAIL */
+		DBG_BUGON(owned == Z_EROFS_PCLUSTER_TAIL);
+
+		/* no possible that 'owned' equals NULL */
+		DBG_BUGON(owned == Z_EROFS_PCLUSTER_NIL);
+
+		pcl = container_of(owned, struct z_erofs_pcluster, next);
+		owned = READ_ONCE(pcl->next);
+
+		z_erofs_decompress_pcluster(io->sb, pcl, pagepool);
+	}
+}
+
+static void z_erofs_decompressqueue_work(struct work_struct *work)
+{
+	struct z_erofs_decompressqueue *bgq =
+		container_of(work, struct z_erofs_decompressqueue, u.work);
+	LIST_HEAD(pagepool);
+
+	DBG_BUGON(bgq->head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
+	z_erofs_decompress_queue(bgq, &pagepool);
+
+	put_pages_list(&pagepool);
+	kvfree(bgq);
+}
+
+static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl,
+					       unsigned int nr,
+					       struct list_head *pagepool,
+					       struct address_space *mc,
+					       gfp_t gfp)
+{
+	const pgoff_t index = pcl->obj.index;
+	bool tocache = false;
+
+	struct address_space *mapping;
+	struct page *oldpage, *page;
+
+	compressed_page_t t;
+	int justfound;
+
+repeat:
+	page = READ_ONCE(pcl->compressed_pages[nr]);
+	oldpage = page;
+
+	if (!page)
+		goto out_allocpage;
+
+	/*
+	 * the cached page has not been allocated and
+	 * an placeholder is out there, prepare it now.
+	 */
+	if (page == PAGE_UNALLOCATED) {
+		tocache = true;
+		goto out_allocpage;
+	}
+
+	/* process the target tagged pointer */
+	t = tagptr_init(compressed_page_t, page);
+	justfound = tagptr_unfold_tags(t);
+	page = tagptr_unfold_ptr(t);
+
+	mapping = READ_ONCE(page->mapping);
+
+	/*
+	 * unmanaged (file) pages are all locked solidly,
+	 * therefore it is impossible for `mapping' to be NULL.
+	 */
+	if (mapping && mapping != mc)
+		/* ought to be unmanaged pages */
+		goto out;
+
+	lock_page(page);
+
+	/* only true if page reclaim goes wrong, should never happen */
+	DBG_BUGON(justfound && PagePrivate(page));
+
+	/* the page is still in manage cache */
+	if (page->mapping == mc) {
+		WRITE_ONCE(pcl->compressed_pages[nr], page);
+
+		ClearPageError(page);
+		if (!PagePrivate(page)) {
+			/*
+			 * impossible to be !PagePrivate(page) for
+			 * the current restriction as well if
+			 * the page is already in compressed_pages[].
+			 */
+			DBG_BUGON(!justfound);
+
+			justfound = 0;
+			set_page_private(page, (unsigned long)pcl);
+			SetPagePrivate(page);
+		}
+
+		/* no need to submit io if it is already up-to-date */
+		if (PageUptodate(page)) {
+			unlock_page(page);
+			page = NULL;
+		}
+		goto out;
+	}
+
+	/*
+	 * the managed page has been truncated, it's unsafe to
+	 * reuse this one, let's allocate a new cache-managed page.
+	 */
+	DBG_BUGON(page->mapping);
+	DBG_BUGON(!justfound);
+
+	tocache = true;
+	unlock_page(page);
+	put_page(page);
+out_allocpage:
+	page = erofs_allocpage(pagepool, gfp | __GFP_NOFAIL);
+	if (!tocache || add_to_page_cache_lru(page, mc, index + nr, gfp)) {
+		/* non-LRU / non-movable temporary page is needed */
+		page->mapping = Z_EROFS_MAPPING_STAGING;
+		tocache = false;
+	}
+
+	if (oldpage != cmpxchg(&pcl->compressed_pages[nr], oldpage, page)) {
+		if (tocache) {
+			/* since it added to managed cache successfully */
+			unlock_page(page);
+			put_page(page);
+		} else {
+			list_add(&page->lru, pagepool);
+		}
+		cond_resched();
+		goto repeat;
+	}
+
+	if (tocache) {
+		set_page_private(page, (unsigned long)pcl);
+		SetPagePrivate(page);
+	}
+out:	/* the only exit (for tracing and debugging) */
+	return page;
+}
+
+static struct z_erofs_decompressqueue *
+jobqueue_init(struct super_block *sb,
+	      struct z_erofs_decompressqueue *fgq, bool *fg)
+{
+	struct z_erofs_decompressqueue *q;
+
+	if (fg && !*fg) {
+		q = kvzalloc(sizeof(*q), GFP_KERNEL | __GFP_NOWARN);
+		if (!q) {
+			*fg = true;
+			goto fg_out;
+		}
+		INIT_WORK(&q->u.work, z_erofs_decompressqueue_work);
+	} else {
+fg_out:
+		q = fgq;
+		init_waitqueue_head(&fgq->u.wait);
+		atomic_set(&fgq->pending_bios, 0);
+	}
+	q->sb = sb;
+	q->head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
+	return q;
+}
+
+/* define decompression jobqueue types */
+enum {
+	JQ_BYPASS,
+	JQ_SUBMIT,
+	NR_JOBQUEUES,
+};
+
+static void *jobqueueset_init(struct super_block *sb,
+			      struct z_erofs_decompressqueue *q[],
+			      struct z_erofs_decompressqueue *fgq, bool *fg)
+{
+	/*
+	 * if managed cache is enabled, bypass jobqueue is needed,
+	 * no need to read from device for all pclusters in this queue.
+	 */
+	q[JQ_BYPASS] = jobqueue_init(sb, fgq + JQ_BYPASS, NULL);
+	q[JQ_SUBMIT] = jobqueue_init(sb, fgq + JQ_SUBMIT, fg);
+
+	return tagptr_cast_ptr(tagptr_fold(tagptr1_t, q[JQ_SUBMIT], *fg));
+}
+
+static void move_to_bypass_jobqueue(struct z_erofs_pcluster *pcl,
+				    z_erofs_next_pcluster_t qtail[],
+				    z_erofs_next_pcluster_t owned_head)
+{
+	z_erofs_next_pcluster_t *const submit_qtail = qtail[JQ_SUBMIT];
+	z_erofs_next_pcluster_t *const bypass_qtail = qtail[JQ_BYPASS];
+
+	DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
+	if (owned_head == Z_EROFS_PCLUSTER_TAIL)
+		owned_head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
+
+	WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_TAIL_CLOSED);
+
+	WRITE_ONCE(*submit_qtail, owned_head);
+	WRITE_ONCE(*bypass_qtail, &pcl->next);
+
+	qtail[JQ_BYPASS] = &pcl->next;
+}
+
+static void z_erofs_submit_queue(struct super_block *sb,
+				 struct z_erofs_decompress_frontend *f,
+				 struct list_head *pagepool,
+				 struct z_erofs_decompressqueue *fgq,
+				 bool *force_fg)
+{
+	struct erofs_sb_info *const sbi = EROFS_SB(sb);
+	z_erofs_next_pcluster_t qtail[NR_JOBQUEUES];
+	struct z_erofs_decompressqueue *q[NR_JOBQUEUES];
+	void *bi_private;
+	z_erofs_next_pcluster_t owned_head = f->clt.owned_head;
+	/* since bio will be NULL, no need to initialize last_index */
+	pgoff_t last_index;
+	unsigned int nr_bios = 0;
+	struct bio *bio = NULL;
+
+	bi_private = jobqueueset_init(sb, q, fgq, force_fg);
+	qtail[JQ_BYPASS] = &q[JQ_BYPASS]->head;
+	qtail[JQ_SUBMIT] = &q[JQ_SUBMIT]->head;
+
+	/* by default, all need io submission */
+	q[JQ_SUBMIT]->head = owned_head;
+
+	do {
+		struct z_erofs_pcluster *pcl;
+		pgoff_t cur, end;
+		unsigned int i = 0;
+		bool bypass = true;
+
+		/* no possible 'owned_head' equals the following */
+		DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
+		DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_NIL);
+
+		pcl = container_of(owned_head, struct z_erofs_pcluster, next);
+
+		cur = pcl->obj.index;
+		end = cur + BIT(pcl->clusterbits);
+
+		/* close the main owned chain at first */
+		owned_head = cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
+				     Z_EROFS_PCLUSTER_TAIL_CLOSED);
+
+		do {
+			struct page *page;
+
+			page = pickup_page_for_submission(pcl, i++, pagepool,
+							  MNGD_MAPPING(sbi),
+							  GFP_NOFS);
+			if (!page)
+				continue;
+
+			if (bio && cur != last_index + 1) {
+submit_bio_retry:
+				submit_bio(bio);
+				bio = NULL;
+			}
+
+			if (!bio) {
+				bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
+
+				bio->bi_end_io = z_erofs_decompressqueue_endio;
+				bio_set_dev(bio, sb->s_bdev);
+				bio->bi_iter.bi_sector = (sector_t)cur <<
+					LOG_SECTORS_PER_BLOCK;
+				bio->bi_private = bi_private;
+				bio->bi_opf = REQ_OP_READ;
+				if (f->readahead)
+					bio->bi_opf |= REQ_RAHEAD;
+				++nr_bios;
+			}
+
+			if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE)
+				goto submit_bio_retry;
+
+			last_index = cur;
+			bypass = false;
+		} while (++cur < end);
+
+		if (!bypass)
+			qtail[JQ_SUBMIT] = &pcl->next;
+		else
+			move_to_bypass_jobqueue(pcl, qtail, owned_head);
+	} while (owned_head != Z_EROFS_PCLUSTER_TAIL);
+
+	if (bio)
+		submit_bio(bio);
+
+	/*
+	 * although background is preferred, no one is pending for submission.
+	 * don't issue workqueue for decompression but drop it directly instead.
+	 */
+	if (!*force_fg && !nr_bios) {
+		kvfree(q[JQ_SUBMIT]);
+		return;
+	}
+	z_erofs_decompress_kickoff(q[JQ_SUBMIT], *force_fg, nr_bios);
+}
+
+static void z_erofs_runqueue(struct super_block *sb,
+			     struct z_erofs_decompress_frontend *f,
+			     struct list_head *pagepool, bool force_fg)
+{
+	struct z_erofs_decompressqueue io[NR_JOBQUEUES];
+
+	if (f->clt.owned_head == Z_EROFS_PCLUSTER_TAIL)
+		return;
+	z_erofs_submit_queue(sb, f, pagepool, io, &force_fg);
+
+	/* handle bypass queue (no i/o pclusters) immediately */
+	z_erofs_decompress_queue(&io[JQ_BYPASS], pagepool);
+
+	if (!force_fg)
+		return;
+
+	/* wait until all bios are completed */
+	io_wait_event(io[JQ_SUBMIT].u.wait,
+		      !atomic_read(&io[JQ_SUBMIT].pending_bios));
+
+	/* handle synchronous decompress queue in the caller context */
+	z_erofs_decompress_queue(&io[JQ_SUBMIT], pagepool);
+}
+
+static int z_erofs_readpage(struct file *file, struct page *page)
+{
+	struct inode *const inode = page->mapping->host;
+	struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
+	int err;
+	LIST_HEAD(pagepool);
+
+	trace_erofs_readpage(page, false);
+
+	f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
+
+	err = z_erofs_do_read_page(&f, page);
+	(void)z_erofs_collector_end(&f.clt);
+
+	/* if some compressed cluster ready, need submit them anyway */
+	z_erofs_runqueue(inode->i_sb, &f, &pagepool, true);
+
+	if (err)
+		erofs_err(inode->i_sb, "failed to read, err [%d]", err);
+
+	if (f.map.mpage)
+		put_page(f.map.mpage);
+
+	/* clean up the remaining free pages */
+	put_pages_list(&pagepool);
+	return err;
+}
+
+static int z_erofs_readpages(struct file *filp, struct address_space *mapping,
+			     struct list_head *pages, unsigned int nr_pages)
+{
+	struct inode *const inode = mapping->host;
+	struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
+
+	bool sync = (nr_pages <= sbi->max_sync_decompress_pages);
+	struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
+	gfp_t gfp = mapping_gfp_constraint(mapping, GFP_KERNEL);
+	struct page *head = NULL;
+	LIST_HEAD(pagepool);
+
+	trace_erofs_readpages(mapping->host, lru_to_page(pages),
+			      nr_pages, false);
+
+	f.headoffset = (erofs_off_t)lru_to_page(pages)->index << PAGE_SHIFT;
+
+	for (; nr_pages; --nr_pages) {
+		struct page *page = lru_to_page(pages);
+
+		prefetchw(&page->flags);
+		list_del(&page->lru);
+
+		/*
+		 * A pure asynchronous readahead is indicated if
+		 * a PG_readahead marked page is hitted at first.
+		 * Let's also do asynchronous decompression for this case.
+		 */
+		sync &= !(PageReadahead(page) && !head);
+
+		if (add_to_page_cache_lru(page, mapping, page->index, gfp)) {
+			list_add(&page->lru, &pagepool);
+			continue;
+		}
+
+		set_page_private(page, (unsigned long)head);
+		head = page;
+	}
+
+	while (head) {
+		struct page *page = head;
+		int err;
+
+		/* traversal in reverse order */
+		head = (void *)page_private(page);
+
+		err = z_erofs_do_read_page(&f, page);
+		if (err)
+			erofs_err(inode->i_sb,
+				  "readahead error at page %lu @ nid %llu",
+				  page->index, EROFS_I(inode)->nid);
+		put_page(page);
+	}
+
+	(void)z_erofs_collector_end(&f.clt);
+
+	z_erofs_runqueue(inode->i_sb, &f, &pagepool, sync);
+
+	if (f.map.mpage)
+		put_page(f.map.mpage);
+
+	/* clean up the remaining free pages */
+	put_pages_list(&pagepool);
+	return 0;
+}
+
+const struct address_space_operations z_erofs_aops = {
+	.readpage = z_erofs_readpage,
+	.readpages = z_erofs_readpages,
+};
diff --git a/drivers/staging/erofs/zdata.h b/drivers/staging/erofs/zdata.h
new file mode 100644
index 000000000000..68da309d5ad7
--- /dev/null
+++ b/drivers/staging/erofs/zdata.h
@@ -0,0 +1,188 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2018 HUAWEI, Inc.
+ *             https://www.huawei.com/
+ */
+#ifndef __EROFS_FS_ZDATA_H
+#define __EROFS_FS_ZDATA_H
+
+#include "internal.h"
+#include "zpvec.h"
+
+#define Z_EROFS_NR_INLINE_PAGEVECS      3
+
+/*
+ * Structure fields follow one of the following exclusion rules.
+ *
+ * I: Modifiable by initialization/destruction paths and read-only
+ *    for everyone else;
+ *
+ * L: Field should be protected by pageset lock;
+ *
+ * A: Field should be accessed / updated in atomic for parallelized code.
+ */
+struct z_erofs_collection {
+	struct mutex lock;
+
+	/* I: page offset of start position of decompression */
+	unsigned short pageofs;
+
+	/* L: maximum relative page index in pagevec[] */
+	unsigned short nr_pages;
+
+	/* L: total number of pages in pagevec[] */
+	unsigned int vcnt;
+
+	union {
+		/* L: inline a certain number of pagevecs for bootstrap */
+		erofs_vtptr_t pagevec[Z_EROFS_NR_INLINE_PAGEVECS];
+
+		/* I: can be used to free the pcluster by RCU. */
+		struct rcu_head rcu;
+	};
+};
+
+#define Z_EROFS_PCLUSTER_FULL_LENGTH    0x00000001
+#define Z_EROFS_PCLUSTER_LENGTH_BIT     1
+
+/*
+ * let's leave a type here in case of introducing
+ * another tagged pointer later.
+ */
+typedef void *z_erofs_next_pcluster_t;
+
+struct z_erofs_pcluster {
+	struct erofs_workgroup obj;
+	struct z_erofs_collection primary_collection;
+
+	/* A: point to next chained pcluster or TAILs */
+	z_erofs_next_pcluster_t next;
+
+	/* A: compressed pages (including multi-usage pages) */
+	struct page *compressed_pages[Z_EROFS_CLUSTER_MAX_PAGES];
+
+	/* A: lower limit of decompressed length and if full length or not */
+	unsigned int length;
+
+	/* I: compression algorithm format */
+	unsigned char algorithmformat;
+	/* I: bit shift of physical cluster size */
+	unsigned char clusterbits;
+};
+
+#define z_erofs_primarycollection(pcluster) (&(pcluster)->primary_collection)
+
+/* let's avoid the valid 32-bit kernel addresses */
+
+/* the chained workgroup has't submitted io (still open) */
+#define Z_EROFS_PCLUSTER_TAIL           ((void *)0x5F0ECAFE)
+/* the chained workgroup has already submitted io */
+#define Z_EROFS_PCLUSTER_TAIL_CLOSED    ((void *)0x5F0EDEAD)
+
+#define Z_EROFS_PCLUSTER_NIL            (NULL)
+
+#define Z_EROFS_WORKGROUP_SIZE  sizeof(struct z_erofs_pcluster)
+
+struct z_erofs_decompressqueue {
+	struct super_block *sb;
+	atomic_t pending_bios;
+	z_erofs_next_pcluster_t head;
+
+	union {
+		wait_queue_head_t wait;
+		struct work_struct work;
+	} u;
+};
+
+#define MNGD_MAPPING(sbi)	((sbi)->managed_cache->i_mapping)
+static inline bool erofs_page_is_managed(const struct erofs_sb_info *sbi,
+					 struct page *page)
+{
+	return page->mapping == MNGD_MAPPING(sbi);
+}
+
+#define Z_EROFS_ONLINEPAGE_COUNT_BITS   2
+#define Z_EROFS_ONLINEPAGE_COUNT_MASK   ((1 << Z_EROFS_ONLINEPAGE_COUNT_BITS) - 1)
+#define Z_EROFS_ONLINEPAGE_INDEX_SHIFT  (Z_EROFS_ONLINEPAGE_COUNT_BITS)
+
+/*
+ * waiters (aka. ongoing_packs): # to unlock the page
+ * sub-index: 0 - for partial page, >= 1 full page sub-index
+ */
+typedef atomic_t z_erofs_onlinepage_t;
+
+/* type punning */
+union z_erofs_onlinepage_converter {
+	z_erofs_onlinepage_t *o;
+	unsigned long *v;
+};
+
+static inline unsigned int z_erofs_onlinepage_index(struct page *page)
+{
+	union z_erofs_onlinepage_converter u;
+
+	DBG_BUGON(!PagePrivate(page));
+	u.v = &page_private(page);
+
+	return atomic_read(u.o) >> Z_EROFS_ONLINEPAGE_INDEX_SHIFT;
+}
+
+static inline void z_erofs_onlinepage_init(struct page *page)
+{
+	union {
+		z_erofs_onlinepage_t o;
+		unsigned long v;
+	/* keep from being unlocked in advance */
+	} u = { .o = ATOMIC_INIT(1) };
+
+	set_page_private(page, u.v);
+	smp_wmb();
+	SetPagePrivate(page);
+}
+
+static inline void z_erofs_onlinepage_fixup(struct page *page,
+	uintptr_t index, bool down)
+{
+	union z_erofs_onlinepage_converter u = { .v = &page_private(page) };
+	int orig, orig_index, val;
+
+repeat:
+	orig = atomic_read(u.o);
+	orig_index = orig >> Z_EROFS_ONLINEPAGE_INDEX_SHIFT;
+	if (orig_index) {
+		if (!index)
+			return;
+
+		DBG_BUGON(orig_index != index);
+	}
+
+	val = (index << Z_EROFS_ONLINEPAGE_INDEX_SHIFT) |
+		((orig & Z_EROFS_ONLINEPAGE_COUNT_MASK) + (unsigned int)down);
+	if (atomic_cmpxchg(u.o, orig, val) != orig)
+		goto repeat;
+}
+
+static inline void z_erofs_onlinepage_endio(struct page *page)
+{
+	union z_erofs_onlinepage_converter u;
+	unsigned int v;
+
+	DBG_BUGON(!PagePrivate(page));
+	u.v = &page_private(page);
+
+	v = atomic_dec_return(u.o);
+	if (!(v & Z_EROFS_ONLINEPAGE_COUNT_MASK)) {
+		ClearPagePrivate(page);
+		if (!PageError(page))
+			SetPageUptodate(page);
+		unlock_page(page);
+	}
+	erofs_dbg("%s, page %p value %x", __func__, page, atomic_read(u.o));
+}
+
+#define Z_EROFS_VMAP_ONSTACK_PAGES	\
+	min_t(unsigned int, THREAD_SIZE / 8 / sizeof(struct page *), 96U)
+#define Z_EROFS_VMAP_GLOBAL_PAGES	2048
+
+#endif
+
diff --git a/drivers/staging/erofs/zmap.c b/drivers/staging/erofs/zmap.c
new file mode 100644
index 000000000000..a13f69cf4026
--- /dev/null
+++ b/drivers/staging/erofs/zmap.c
@@ -0,0 +1,477 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2018-2019 HUAWEI, Inc.
+ *             https://www.huawei.com/
+ */
+#include "internal.h"
+#include <asm/unaligned.h>
+#include <trace/events/erofs.h>
+
+int z_erofs_fill_inode(struct inode *inode)
+{
+	struct erofs_inode *const vi = EROFS_I(inode);
+
+	if (vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY) {
+		vi->z_advise = 0;
+		vi->z_algorithmtype[0] = 0;
+		vi->z_algorithmtype[1] = 0;
+		vi->z_logical_clusterbits = LOG_BLOCK_SIZE;
+		vi->z_physical_clusterbits[0] = vi->z_logical_clusterbits;
+		vi->z_physical_clusterbits[1] = vi->z_logical_clusterbits;
+		set_bit(EROFS_I_Z_INITED_BIT, &vi->flags);
+	}
+
+	inode->i_mapping->a_ops = &z_erofs_aops;
+	return 0;
+}
+
+static int z_erofs_fill_inode_lazy(struct inode *inode)
+{
+	struct erofs_inode *const vi = EROFS_I(inode);
+	struct super_block *const sb = inode->i_sb;
+	int err;
+	erofs_off_t pos;
+	struct page *page;
+	void *kaddr;
+	struct z_erofs_map_header *h;
+
+	if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags)) {
+		/*
+		 * paired with smp_mb() at the end of the function to ensure
+		 * fields will only be observed after the bit is set.
+		 */
+		smp_mb();
+		return 0;
+	}
+
+	if (wait_on_bit_lock(&vi->flags, EROFS_I_BL_Z_BIT, TASK_KILLABLE))
+		return -ERESTARTSYS;
+
+	err = 0;
+	if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags))
+		goto out_unlock;
+
+	DBG_BUGON(vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY);
+
+	pos = ALIGN(iloc(EROFS_SB(sb), vi->nid) + vi->inode_isize +
+		    vi->xattr_isize, 8);
+	page = erofs_get_meta_page(sb, erofs_blknr(pos));
+	if (IS_ERR(page)) {
+		err = PTR_ERR(page);
+		goto out_unlock;
+	}
+
+	kaddr = kmap_atomic(page);
+
+	h = kaddr + erofs_blkoff(pos);
+	vi->z_advise = le16_to_cpu(h->h_advise);
+	vi->z_algorithmtype[0] = h->h_algorithmtype & 15;
+	vi->z_algorithmtype[1] = h->h_algorithmtype >> 4;
+
+	if (vi->z_algorithmtype[0] >= Z_EROFS_COMPRESSION_MAX) {
+		erofs_err(sb, "unknown compression format %u for nid %llu, please upgrade kernel",
+			  vi->z_algorithmtype[0], vi->nid);
+		err = -EOPNOTSUPP;
+		goto unmap_done;
+	}
+
+	vi->z_logical_clusterbits = LOG_BLOCK_SIZE + (h->h_clusterbits & 7);
+	vi->z_physical_clusterbits[0] = vi->z_logical_clusterbits +
+					((h->h_clusterbits >> 3) & 3);
+
+	if (vi->z_physical_clusterbits[0] != LOG_BLOCK_SIZE) {
+		erofs_err(sb, "unsupported physical clusterbits %u for nid %llu, please upgrade kernel",
+			  vi->z_physical_clusterbits[0], vi->nid);
+		err = -EOPNOTSUPP;
+		goto unmap_done;
+	}
+
+	vi->z_physical_clusterbits[1] = vi->z_logical_clusterbits +
+					((h->h_clusterbits >> 5) & 7);
+	/* paired with smp_mb() at the beginning of the function */
+	smp_mb();
+	set_bit(EROFS_I_Z_INITED_BIT, &vi->flags);
+unmap_done:
+	kunmap_atomic(kaddr);
+	unlock_page(page);
+	put_page(page);
+out_unlock:
+	clear_and_wake_up_bit(EROFS_I_BL_Z_BIT, &vi->flags);
+	return err;
+}
+
+struct z_erofs_maprecorder {
+	struct inode *inode;
+	struct erofs_map_blocks *map;
+	void *kaddr;
+
+	unsigned long lcn;
+	/* compression extent information gathered */
+	u8  type;
+	u16 clusterofs;
+	u16 delta[2];
+	erofs_blk_t pblk;
+};
+
+static int z_erofs_reload_indexes(struct z_erofs_maprecorder *m,
+				  erofs_blk_t eblk)
+{
+	struct super_block *const sb = m->inode->i_sb;
+	struct erofs_map_blocks *const map = m->map;
+	struct page *mpage = map->mpage;
+
+	if (mpage) {
+		if (mpage->index == eblk) {
+			if (!m->kaddr)
+				m->kaddr = kmap_atomic(mpage);
+			return 0;
+		}
+
+		if (m->kaddr) {
+			kunmap_atomic(m->kaddr);
+			m->kaddr = NULL;
+		}
+		put_page(mpage);
+	}
+
+	mpage = erofs_get_meta_page(sb, eblk);
+	if (IS_ERR(mpage)) {
+		map->mpage = NULL;
+		return PTR_ERR(mpage);
+	}
+	m->kaddr = kmap_atomic(mpage);
+	unlock_page(mpage);
+	map->mpage = mpage;
+	return 0;
+}
+
+static int legacy_load_cluster_from_disk(struct z_erofs_maprecorder *m,
+					 unsigned long lcn)
+{
+	struct inode *const inode = m->inode;
+	struct erofs_inode *const vi = EROFS_I(inode);
+	const erofs_off_t ibase = iloc(EROFS_I_SB(inode), vi->nid);
+	const erofs_off_t pos =
+		Z_EROFS_VLE_LEGACY_INDEX_ALIGN(ibase + vi->inode_isize +
+					       vi->xattr_isize) +
+		lcn * sizeof(struct z_erofs_vle_decompressed_index);
+	struct z_erofs_vle_decompressed_index *di;
+	unsigned int advise, type;
+	int err;
+
+	err = z_erofs_reload_indexes(m, erofs_blknr(pos));
+	if (err)
+		return err;
+
+	m->lcn = lcn;
+	di = m->kaddr + erofs_blkoff(pos);
+
+	advise = le16_to_cpu(di->di_advise);
+	type = (advise >> Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT) &
+		((1 << Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) - 1);
+	switch (type) {
+	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+		m->clusterofs = 1 << vi->z_logical_clusterbits;
+		m->delta[0] = le16_to_cpu(di->di_u.delta[0]);
+		m->delta[1] = le16_to_cpu(di->di_u.delta[1]);
+		break;
+	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
+	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
+		m->clusterofs = le16_to_cpu(di->di_clusterofs);
+		m->pblk = le32_to_cpu(di->di_u.blkaddr);
+		break;
+	default:
+		DBG_BUGON(1);
+		return -EOPNOTSUPP;
+	}
+	m->type = type;
+	return 0;
+}
+
+static unsigned int decode_compactedbits(unsigned int lobits,
+					 unsigned int lomask,
+					 u8 *in, unsigned int pos, u8 *type)
+{
+	const unsigned int v = get_unaligned_le32(in + pos / 8) >> (pos & 7);
+	const unsigned int lo = v & lomask;
+
+	*type = (v >> lobits) & 3;
+	return lo;
+}
+
+static int unpack_compacted_index(struct z_erofs_maprecorder *m,
+				  unsigned int amortizedshift,
+				  unsigned int eofs)
+{
+	struct erofs_inode *const vi = EROFS_I(m->inode);
+	const unsigned int lclusterbits = vi->z_logical_clusterbits;
+	const unsigned int lomask = (1 << lclusterbits) - 1;
+	unsigned int vcnt, base, lo, encodebits, nblk;
+	int i;
+	u8 *in, type;
+
+	if (1 << amortizedshift == 4)
+		vcnt = 2;
+	else if (1 << amortizedshift == 2 && lclusterbits == 12)
+		vcnt = 16;
+	else
+		return -EOPNOTSUPP;
+
+	encodebits = ((vcnt << amortizedshift) - sizeof(__le32)) * 8 / vcnt;
+	base = round_down(eofs, vcnt << amortizedshift);
+	in = m->kaddr + base;
+
+	i = (eofs - base) >> amortizedshift;
+
+	lo = decode_compactedbits(lclusterbits, lomask,
+				  in, encodebits * i, &type);
+	m->type = type;
+	if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
+		m->clusterofs = 1 << lclusterbits;
+		if (i + 1 != vcnt) {
+			m->delta[0] = lo;
+			return 0;
+		}
+		/*
+		 * since the last lcluster in the pack is special,
+		 * of which lo saves delta[1] rather than delta[0].
+		 * Hence, get delta[0] by the previous lcluster indirectly.
+		 */
+		lo = decode_compactedbits(lclusterbits, lomask,
+					  in, encodebits * (i - 1), &type);
+		if (type != Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
+			lo = 0;
+		m->delta[0] = lo + 1;
+		return 0;
+	}
+	m->clusterofs = lo;
+	m->delta[0] = 0;
+	/* figout out blkaddr (pblk) for HEAD lclusters */
+	nblk = 1;
+	while (i > 0) {
+		--i;
+		lo = decode_compactedbits(lclusterbits, lomask,
+					  in, encodebits * i, &type);
+		if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
+			i -= lo;
+
+		if (i >= 0)
+			++nblk;
+	}
+	in += (vcnt << amortizedshift) - sizeof(__le32);
+	m->pblk = le32_to_cpu(*(__le32 *)in) + nblk;
+	return 0;
+}
+
+static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m,
+					    unsigned long lcn)
+{
+	struct inode *const inode = m->inode;
+	struct erofs_inode *const vi = EROFS_I(inode);
+	const unsigned int lclusterbits = vi->z_logical_clusterbits;
+	const erofs_off_t ebase = ALIGN(iloc(EROFS_I_SB(inode), vi->nid) +
+					vi->inode_isize + vi->xattr_isize, 8) +
+		sizeof(struct z_erofs_map_header);
+	const unsigned int totalidx = DIV_ROUND_UP(inode->i_size, EROFS_BLKSIZ);
+	unsigned int compacted_4b_initial, compacted_2b;
+	unsigned int amortizedshift;
+	erofs_off_t pos;
+	int err;
+
+	if (lclusterbits != 12)
+		return -EOPNOTSUPP;
+
+	if (lcn >= totalidx)
+		return -EINVAL;
+
+	m->lcn = lcn;
+	/* used to align to 32-byte (compacted_2b) alignment */
+	compacted_4b_initial = (32 - ebase % 32) / 4;
+	if (compacted_4b_initial == 32 / 4)
+		compacted_4b_initial = 0;
+
+	if (vi->z_advise & Z_EROFS_ADVISE_COMPACTED_2B)
+		compacted_2b = rounddown(totalidx - compacted_4b_initial, 16);
+	else
+		compacted_2b = 0;
+
+	pos = ebase;
+	if (lcn < compacted_4b_initial) {
+		amortizedshift = 2;
+		goto out;
+	}
+	pos += compacted_4b_initial * 4;
+	lcn -= compacted_4b_initial;
+
+	if (lcn < compacted_2b) {
+		amortizedshift = 1;
+		goto out;
+	}
+	pos += compacted_2b * 2;
+	lcn -= compacted_2b;
+	amortizedshift = 2;
+out:
+	pos += lcn * (1 << amortizedshift);
+	err = z_erofs_reload_indexes(m, erofs_blknr(pos));
+	if (err)
+		return err;
+	return unpack_compacted_index(m, amortizedshift, erofs_blkoff(pos));
+}
+
+static int z_erofs_load_cluster_from_disk(struct z_erofs_maprecorder *m,
+					  unsigned int lcn)
+{
+	const unsigned int datamode = EROFS_I(m->inode)->datalayout;
+
+	if (datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY)
+		return legacy_load_cluster_from_disk(m, lcn);
+
+	if (datamode == EROFS_INODE_FLAT_COMPRESSION)
+		return compacted_load_cluster_from_disk(m, lcn);
+
+	return -EINVAL;
+}
+
+static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m,
+				   unsigned int lookback_distance)
+{
+	struct erofs_inode *const vi = EROFS_I(m->inode);
+	struct erofs_map_blocks *const map = m->map;
+	const unsigned int lclusterbits = vi->z_logical_clusterbits;
+	unsigned long lcn = m->lcn;
+	int err;
+
+	if (lcn < lookback_distance) {
+		erofs_err(m->inode->i_sb,
+			  "bogus lookback distance @ nid %llu", vi->nid);
+		DBG_BUGON(1);
+		return -EFSCORRUPTED;
+	}
+
+	/* load extent head logical cluster if needed */
+	lcn -= lookback_distance;
+	err = z_erofs_load_cluster_from_disk(m, lcn);
+	if (err)
+		return err;
+
+	switch (m->type) {
+	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+		if (!m->delta[0]) {
+			erofs_err(m->inode->i_sb,
+				  "invalid lookback distance 0 @ nid %llu",
+				  vi->nid);
+			DBG_BUGON(1);
+			return -EFSCORRUPTED;
+		}
+		return z_erofs_extent_lookback(m, m->delta[0]);
+	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
+		map->m_flags &= ~EROFS_MAP_ZIPPED;
+		/* fallthrough */
+	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
+		map->m_la = (lcn << lclusterbits) | m->clusterofs;
+		break;
+	default:
+		erofs_err(m->inode->i_sb,
+			  "unknown type %u @ lcn %lu of nid %llu",
+			  m->type, lcn, vi->nid);
+		DBG_BUGON(1);
+		return -EOPNOTSUPP;
+	}
+	return 0;
+}
+
+int z_erofs_map_blocks_iter(struct inode *inode,
+			    struct erofs_map_blocks *map,
+			    int flags)
+{
+	struct erofs_inode *const vi = EROFS_I(inode);
+	struct z_erofs_maprecorder m = {
+		.inode = inode,
+		.map = map,
+	};
+	int err = 0;
+	unsigned int lclusterbits, endoff;
+	unsigned long long ofs, end;
+
+	trace_z_erofs_map_blocks_iter_enter(inode, map, flags);
+
+	/* when trying to read beyond EOF, leave it unmapped */
+	if (map->m_la >= inode->i_size) {
+		map->m_llen = map->m_la + 1 - inode->i_size;
+		map->m_la = inode->i_size;
+		map->m_flags = 0;
+		goto out;
+	}
+
+	err = z_erofs_fill_inode_lazy(inode);
+	if (err)
+		goto out;
+
+	lclusterbits = vi->z_logical_clusterbits;
+	ofs = map->m_la;
+	m.lcn = ofs >> lclusterbits;
+	endoff = ofs & ((1 << lclusterbits) - 1);
+
+	err = z_erofs_load_cluster_from_disk(&m, m.lcn);
+	if (err)
+		goto unmap_out;
+
+	map->m_flags = EROFS_MAP_ZIPPED;	/* by default, compressed */
+	end = (m.lcn + 1ULL) << lclusterbits;
+
+	switch (m.type) {
+	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
+		if (endoff >= m.clusterofs)
+			map->m_flags &= ~EROFS_MAP_ZIPPED;
+		/* fallthrough */
+	case Z_EROFS_VLE_CLUSTER_TYPE_HEAD:
+		if (endoff >= m.clusterofs) {
+			map->m_la = (m.lcn << lclusterbits) | m.clusterofs;
+			break;
+		}
+		/* m.lcn should be >= 1 if endoff < m.clusterofs */
+		if (!m.lcn) {
+			erofs_err(inode->i_sb,
+				  "invalid logical cluster 0 at nid %llu",
+				  vi->nid);
+			err = -EFSCORRUPTED;
+			goto unmap_out;
+		}
+		end = (m.lcn << lclusterbits) | m.clusterofs;
+		map->m_flags |= EROFS_MAP_FULL_MAPPED;
+		m.delta[0] = 1;
+		/* fallthrough */
+	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+		/* get the correspoinding first chunk */
+		err = z_erofs_extent_lookback(&m, m.delta[0]);
+		if (err)
+			goto unmap_out;
+		break;
+	default:
+		erofs_err(inode->i_sb,
+			  "unknown type %u @ offset %llu of nid %llu",
+			  m.type, ofs, vi->nid);
+		err = -EOPNOTSUPP;
+		goto unmap_out;
+	}
+
+	map->m_llen = end - map->m_la;
+	map->m_plen = 1 << lclusterbits;
+	map->m_pa = blknr_to_addr(m.pblk);
+	map->m_flags |= EROFS_MAP_MAPPED;
+
+unmap_out:
+	if (m.kaddr)
+		kunmap_atomic(m.kaddr);
+
+out:
+	erofs_dbg("%s, m_la %llu m_pa %llu m_llen %llu m_plen %llu m_flags 0%o",
+		  __func__, map->m_la, map->m_pa,
+		  map->m_llen, map->m_plen, map->m_flags);
+
+	trace_z_erofs_map_blocks_iter_exit(inode, map, flags, err);
+
+	/* aggressively BUG_ON iff CONFIG_EROFS_FS_DEBUG is on */
+	DBG_BUGON(err < 0 && err != -ENOMEM);
+	return err;
+}
diff --git a/drivers/staging/erofs/unzip_pagevec.h b/drivers/staging/erofs/zpvec.h
similarity index 67%
rename from drivers/staging/erofs/unzip_pagevec.h
rename to drivers/staging/erofs/zpvec.h
index 23856ba2742d..bfc12ecbbe83 100644
--- a/drivers/staging/erofs/unzip_pagevec.h
+++ b/drivers/staging/erofs/zpvec.h
@@ -1,21 +1,14 @@
-/* SPDX-License-Identifier: GPL-2.0
- *
- * linux/drivers/staging/erofs/unzip_pagevec.h
- *
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
  * Copyright (C) 2018 HUAWEI, Inc.
- *             http://www.huawei.com/
- * Created by Gao Xiang <gaoxiang25@huawei.com>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file COPYING in the main directory of the Linux
- * distribution for more details.
+ *             https://www.huawei.com/
  */
-#ifndef __EROFS_UNZIP_PAGEVEC_H
-#define __EROFS_UNZIP_PAGEVEC_H
+#ifndef __EROFS_FS_ZPVEC_H
+#define __EROFS_FS_ZPVEC_H
 
-#include <linux/tagptr.h>
+#include "tagptr.h"
 
-/* page type in pagevec for unzip subsystem */
+/* page type in pagevec for decompress subsystem */
 enum z_erofs_page_type {
 	/* including Z_EROFS_VLE_PAGE_TAIL_EXCLUSIVE */
 	Z_EROFS_PAGE_TYPE_EXCLUSIVE,
@@ -43,7 +36,7 @@ struct z_erofs_pagevec_ctor {
 static inline void z_erofs_pagevec_ctor_exit(struct z_erofs_pagevec_ctor *ctor,
 					     bool atomic)
 {
-	if (ctor->curr == NULL)
+	if (!ctor->curr)
 		return;
 
 	if (atomic)
@@ -54,25 +47,22 @@ static inline void z_erofs_pagevec_ctor_exit(struct z_erofs_pagevec_ctor *ctor,
 
 static inline struct page *
 z_erofs_pagevec_ctor_next_page(struct z_erofs_pagevec_ctor *ctor,
-			       unsigned nr)
+			       unsigned int nr)
 {
-	unsigned index;
+	unsigned int index;
 
 	/* keep away from occupied pages */
-	if (ctor->next != NULL)
+	if (ctor->next)
 		return ctor->next;
 
 	for (index = 0; index < nr; ++index) {
 		const erofs_vtptr_t t = ctor->pages[index];
-		const unsigned tags = tagptr_unfold_tags(t);
+		const unsigned int tags = tagptr_unfold_tags(t);
 
 		if (tags == Z_EROFS_PAGE_TYPE_EXCLUSIVE)
 			return tagptr_unfold_ptr(t);
 	}
-
-	if (unlikely(nr >= ctor->nr))
-		BUG();
-
+	DBG_BUGON(nr >= ctor->nr);
 	return NULL;
 }
 
@@ -94,8 +84,9 @@ z_erofs_pagevec_ctor_pagedown(struct z_erofs_pagevec_ctor *ctor,
 }
 
 static inline void z_erofs_pagevec_ctor_init(struct z_erofs_pagevec_ctor *ctor,
-					     unsigned nr,
-					     erofs_vtptr_t *pages, unsigned i)
+					     unsigned int nr,
+					     erofs_vtptr_t *pages,
+					     unsigned int i)
 {
 	ctor->nr = nr;
 	ctor->curr = ctor->next = NULL;
@@ -109,23 +100,21 @@ static inline void z_erofs_pagevec_ctor_init(struct z_erofs_pagevec_ctor *ctor,
 			z_erofs_pagevec_ctor_pagedown(ctor, false);
 		}
 	}
-
 	ctor->next = z_erofs_pagevec_ctor_next_page(ctor, i);
 	ctor->index = i;
 }
 
-static inline bool
-z_erofs_pagevec_ctor_enqueue(struct z_erofs_pagevec_ctor *ctor,
-			     struct page *page,
-			     enum z_erofs_page_type type,
-			     bool *occupied)
+static inline bool z_erofs_pagevec_enqueue(struct z_erofs_pagevec_ctor *ctor,
+					   struct page *page,
+					   enum z_erofs_page_type type,
+					   bool *occupied)
 {
 	*occupied = false;
-	if (unlikely(ctor->next == NULL && type))
+	if (!ctor->next && type)
 		if (ctor->index + 1 == ctor->nr)
 			return false;
 
-	if (unlikely(ctor->index >= ctor->nr))
+	if (ctor->index >= ctor->nr)
 		z_erofs_pagevec_ctor_pagedown(ctor, false);
 
 	/* exclusive page type must be 0 */
@@ -137,19 +126,17 @@ z_erofs_pagevec_ctor_enqueue(struct z_erofs_pagevec_ctor *ctor,
 		ctor->next = page;
 		*occupied = true;
 	}
-
-	ctor->pages[ctor->index++] =
-		tagptr_fold(erofs_vtptr_t, page, type);
+	ctor->pages[ctor->index++] = tagptr_fold(erofs_vtptr_t, page, type);
 	return true;
 }
 
 static inline struct page *
-z_erofs_pagevec_ctor_dequeue(struct z_erofs_pagevec_ctor *ctor,
-			     enum z_erofs_page_type *type)
+z_erofs_pagevec_dequeue(struct z_erofs_pagevec_ctor *ctor,
+			enum z_erofs_page_type *type)
 {
 	erofs_vtptr_t t;
 
-	if (unlikely(ctor->index >= ctor->nr)) {
+	if (ctor->index >= ctor->nr) {
 		DBG_BUGON(!ctor->next);
 		z_erofs_pagevec_ctor_pagedown(ctor, true);
 	}
@@ -162,11 +149,7 @@ z_erofs_pagevec_ctor_dequeue(struct z_erofs_pagevec_ctor *ctor,
 	if (*type == (uintptr_t)ctor->next)
 		ctor->next = tagptr_unfold_ptr(t);
 
-	ctor->pages[ctor->index++] =
-		tagptr_fold(erofs_vtptr_t, NULL, 0);
-
+	ctor->pages[ctor->index++] = tagptr_fold(erofs_vtptr_t, NULL, 0);
 	return tagptr_unfold_ptr(t);
 }
-
 #endif
-
diff --git a/drivers/staging/erofs/include/trace/events/erofs.h b/include/trace/events/erofs.h
similarity index 85%
rename from drivers/staging/erofs/include/trace/events/erofs.h
rename to include/trace/events/erofs.h
index 5aead93a762f..27f5caa6299a 100644
--- a/drivers/staging/erofs/include/trace/events/erofs.h
+++ b/include/trace/events/erofs.h
@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: GPL-2.0 */
+/* SPDX-License-Identifier: GPL-2.0-only */
 #undef TRACE_SYSTEM
 #define TRACE_SYSTEM erofs
 
@@ -6,6 +6,9 @@
 #define _TRACE_EROFS_H
 
 #include <linux/tracepoint.h>
+#include <linux/fs.h>
+
+struct erofs_map_blocks;
 
 #define show_dev(dev)		MAJOR(dev), MINOR(dev)
 #define show_dev_nid(entry)	show_dev(entry->dev), entry->nid
@@ -38,7 +41,7 @@ TRACE_EVENT(erofs_lookup,
 
 	TP_fast_assign(
 		__entry->dev	= dir->i_sb->s_dev;
-		__entry->nid	= EROFS_V(dir)->nid;
+		__entry->nid	= EROFS_I(dir)->nid;
 		__entry->name	= dentry->d_name.name;
 		__entry->flags	= flags;
 	),
@@ -63,7 +66,7 @@ TRACE_EVENT(erofs_fill_inode,
 
 	TP_fast_assign(
 		__entry->dev		= inode->i_sb->s_dev;
-		__entry->nid		= EROFS_V(inode)->nid;
+		__entry->nid		= EROFS_I(inode)->nid;
 		__entry->blkaddr	= erofs_blknr(iloc(EROFS_I_SB(inode), __entry->nid));
 		__entry->ofs		= erofs_blkoff(iloc(EROFS_I_SB(inode), __entry->nid));
 		__entry->isdir		= isdir;
@@ -92,7 +95,7 @@ TRACE_EVENT(erofs_readpage,
 
 	TP_fast_assign(
 		__entry->dev	= page->mapping->host->i_sb->s_dev;
-		__entry->nid	= EROFS_V(page->mapping->host)->nid;
+		__entry->nid	= EROFS_I(page->mapping->host)->nid;
 		__entry->dir	= S_ISDIR(page->mapping->host->i_mode);
 		__entry->index	= page->index;
 		__entry->uptodate = PageUptodate(page);
@@ -125,7 +128,7 @@ TRACE_EVENT(erofs_readpages,
 
 	TP_fast_assign(
 		__entry->dev	= inode->i_sb->s_dev;
-		__entry->nid	= EROFS_V(inode)->nid;
+		__entry->nid	= EROFS_I(inode)->nid;
 		__entry->start	= page->index;
 		__entry->nrpage	= nrpage;
 		__entry->raw	= raw;
@@ -154,7 +157,7 @@ DECLARE_EVENT_CLASS(erofs__map_blocks_enter,
 
 	TP_fast_assign(
 		__entry->dev    = inode->i_sb->s_dev;
-		__entry->nid    = EROFS_V(inode)->nid;
+		__entry->nid    = EROFS_I(inode)->nid;
 		__entry->la	= map->m_la;
 		__entry->llen	= map->m_llen;
 		__entry->flags	= flags;
@@ -162,7 +165,8 @@ DECLARE_EVENT_CLASS(erofs__map_blocks_enter,
 
 	TP_printk("dev = (%d,%d), nid = %llu, la %llu llen %llu flags %s",
 		  show_dev_nid(__entry),
-		  __entry->la, __entry->llen, show_map_flags(__entry->flags))
+		  __entry->la, __entry->llen,
+		  __entry->flags ? show_map_flags(__entry->flags) : "NULL")
 );
 
 DEFINE_EVENT(erofs__map_blocks_enter, erofs_map_blocks_flatmode_enter,
@@ -172,6 +176,13 @@ DEFINE_EVENT(erofs__map_blocks_enter, erofs_map_blocks_flatmode_enter,
 	TP_ARGS(inode, map, flags)
 );
 
+DEFINE_EVENT(erofs__map_blocks_enter, z_erofs_map_blocks_iter_enter,
+	TP_PROTO(struct inode *inode, struct erofs_map_blocks *map,
+		 unsigned int flags),
+
+	TP_ARGS(inode, map, flags)
+);
+
 DECLARE_EVENT_CLASS(erofs__map_blocks_exit,
 	TP_PROTO(struct inode *inode, struct erofs_map_blocks *map,
 		 unsigned int flags, int ret),
@@ -192,7 +203,7 @@ DECLARE_EVENT_CLASS(erofs__map_blocks_exit,
 
 	TP_fast_assign(
 		__entry->dev    = inode->i_sb->s_dev;
-		__entry->nid    = EROFS_V(inode)->nid;
+		__entry->nid    = EROFS_I(inode)->nid;
 		__entry->flags	= flags;
 		__entry->la	= map->m_la;
 		__entry->pa	= map->m_pa;
@@ -204,7 +215,8 @@ DECLARE_EVENT_CLASS(erofs__map_blocks_exit,
 
 	TP_printk("dev = (%d,%d), nid = %llu, flags %s "
 		  "la %llu pa %llu llen %llu plen %llu mflags %s ret %d",
-		  show_dev_nid(__entry), show_map_flags(__entry->flags),
+		  show_dev_nid(__entry),
+		  __entry->flags ? show_map_flags(__entry->flags) : "NULL",
 		  __entry->la, __entry->pa, __entry->llen, __entry->plen,
 		  show_mflags(__entry->mflags), __entry->ret)
 );
@@ -216,6 +228,13 @@ DEFINE_EVENT(erofs__map_blocks_exit, erofs_map_blocks_flatmode_exit,
 	TP_ARGS(inode, map, flags, ret)
 );
 
+DEFINE_EVENT(erofs__map_blocks_exit, z_erofs_map_blocks_iter_exit,
+	TP_PROTO(struct inode *inode, struct erofs_map_blocks *map,
+		 unsigned int flags, int ret),
+
+	TP_ARGS(inode, map, flags, ret)
+);
+
 TRACE_EVENT(erofs_destroy_inode,
 	TP_PROTO(struct inode *inode),
 
@@ -228,7 +247,7 @@ TRACE_EVENT(erofs_destroy_inode,
 
 	TP_fast_assign(
 		__entry->dev	= inode->i_sb->s_dev;
-		__entry->nid	= EROFS_V(inode)->nid;
+		__entry->nid	= EROFS_I(inode)->nid;
 	),
 
 	TP_printk("dev = (%d,%d), nid = %llu", show_dev_nid(__entry))