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955 lines
25 KiB
955 lines
25 KiB
/*
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* zswap.c - zswap driver file
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*
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* zswap is a backend for frontswap that takes pages that are in the process
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* of being swapped out and attempts to compress and store them in a
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* RAM-based memory pool. This can result in a significant I/O reduction on
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* the swap device and, in the case where decompressing from RAM is faster
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* than reading from the swap device, can also improve workload performance.
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*
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* Copyright (C) 2012 Seth Jennings <sjenning@linux.vnet.ibm.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/cpu.h>
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#include <linux/highmem.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/types.h>
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#include <linux/atomic.h>
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#include <linux/frontswap.h>
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#include <linux/rbtree.h>
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#include <linux/swap.h>
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#include <linux/crypto.h>
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#include <linux/mempool.h>
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#include <linux/zpool.h>
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#include <linux/mm_types.h>
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#include <linux/page-flags.h>
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#include <linux/swapops.h>
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#include <linux/writeback.h>
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#include <linux/pagemap.h>
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/*********************************
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* statistics
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**********************************/
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/* Total bytes used by the compressed storage */
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static u64 zswap_pool_total_size;
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/* The number of compressed pages currently stored in zswap */
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static atomic_t zswap_stored_pages = ATOMIC_INIT(0);
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/*
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* The statistics below are not protected from concurrent access for
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* performance reasons so they may not be a 100% accurate. However,
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* they do provide useful information on roughly how many times a
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* certain event is occurring.
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*/
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/* Pool limit was hit (see zswap_max_pool_percent) */
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static u64 zswap_pool_limit_hit;
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/* Pages written back when pool limit was reached */
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static u64 zswap_written_back_pages;
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/* Store failed due to a reclaim failure after pool limit was reached */
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static u64 zswap_reject_reclaim_fail;
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/* Compressed page was too big for the allocator to (optimally) store */
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static u64 zswap_reject_compress_poor;
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/* Store failed because underlying allocator could not get memory */
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static u64 zswap_reject_alloc_fail;
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/* Store failed because the entry metadata could not be allocated (rare) */
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static u64 zswap_reject_kmemcache_fail;
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/* Duplicate store was encountered (rare) */
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static u64 zswap_duplicate_entry;
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/*********************************
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* tunables
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**********************************/
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/* Enable/disable zswap (disabled by default, fixed at boot for now) */
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static bool zswap_enabled __read_mostly;
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module_param_named(enabled, zswap_enabled, bool, 0444);
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/* Compressor to be used by zswap (fixed at boot for now) */
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#define ZSWAP_COMPRESSOR_DEFAULT "lzo"
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static char *zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
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module_param_named(compressor, zswap_compressor, charp, 0444);
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/* The maximum percentage of memory that the compressed pool can occupy */
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static unsigned int zswap_max_pool_percent = 20;
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module_param_named(max_pool_percent,
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zswap_max_pool_percent, uint, 0644);
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/* Compressed storage to use */
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#define ZSWAP_ZPOOL_DEFAULT "zbud"
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static char *zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
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module_param_named(zpool, zswap_zpool_type, charp, 0444);
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/* zpool is shared by all of zswap backend */
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static struct zpool *zswap_pool;
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/*********************************
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* compression functions
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**********************************/
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/* per-cpu compression transforms */
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static struct crypto_comp * __percpu *zswap_comp_pcpu_tfms;
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enum comp_op {
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ZSWAP_COMPOP_COMPRESS,
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ZSWAP_COMPOP_DECOMPRESS
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};
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static int zswap_comp_op(enum comp_op op, const u8 *src, unsigned int slen,
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u8 *dst, unsigned int *dlen)
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{
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struct crypto_comp *tfm;
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int ret;
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tfm = *per_cpu_ptr(zswap_comp_pcpu_tfms, get_cpu());
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switch (op) {
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case ZSWAP_COMPOP_COMPRESS:
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ret = crypto_comp_compress(tfm, src, slen, dst, dlen);
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break;
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case ZSWAP_COMPOP_DECOMPRESS:
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ret = crypto_comp_decompress(tfm, src, slen, dst, dlen);
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break;
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default:
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ret = -EINVAL;
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}
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put_cpu();
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return ret;
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}
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static int __init zswap_comp_init(void)
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{
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if (!crypto_has_comp(zswap_compressor, 0, 0)) {
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pr_info("%s compressor not available\n", zswap_compressor);
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/* fall back to default compressor */
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zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
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if (!crypto_has_comp(zswap_compressor, 0, 0))
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/* can't even load the default compressor */
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return -ENODEV;
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}
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pr_info("using %s compressor\n", zswap_compressor);
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/* alloc percpu transforms */
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zswap_comp_pcpu_tfms = alloc_percpu(struct crypto_comp *);
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if (!zswap_comp_pcpu_tfms)
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return -ENOMEM;
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return 0;
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}
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static void zswap_comp_exit(void)
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{
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/* free percpu transforms */
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if (zswap_comp_pcpu_tfms)
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free_percpu(zswap_comp_pcpu_tfms);
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}
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/*********************************
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* data structures
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**********************************/
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/*
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* struct zswap_entry
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*
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* This structure contains the metadata for tracking a single compressed
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* page within zswap.
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*
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* rbnode - links the entry into red-black tree for the appropriate swap type
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* refcount - the number of outstanding reference to the entry. This is needed
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* to protect against premature freeing of the entry by code
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* concurrent calls to load, invalidate, and writeback. The lock
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* for the zswap_tree structure that contains the entry must
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* be held while changing the refcount. Since the lock must
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* be held, there is no reason to also make refcount atomic.
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* offset - the swap offset for the entry. Index into the red-black tree.
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* handle - zpool allocation handle that stores the compressed page data
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* length - the length in bytes of the compressed page data. Needed during
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* decompression
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*/
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struct zswap_entry {
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struct rb_node rbnode;
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pgoff_t offset;
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int refcount;
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unsigned int length;
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unsigned long handle;
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};
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struct zswap_header {
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swp_entry_t swpentry;
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};
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/*
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* The tree lock in the zswap_tree struct protects a few things:
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* - the rbtree
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* - the refcount field of each entry in the tree
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*/
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struct zswap_tree {
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struct rb_root rbroot;
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spinlock_t lock;
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};
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static struct zswap_tree *zswap_trees[MAX_SWAPFILES];
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/*********************************
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* zswap entry functions
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**********************************/
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static struct kmem_cache *zswap_entry_cache;
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static int zswap_entry_cache_create(void)
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{
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zswap_entry_cache = KMEM_CACHE(zswap_entry, 0);
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return zswap_entry_cache == NULL;
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}
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static void __init zswap_entry_cache_destroy(void)
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{
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kmem_cache_destroy(zswap_entry_cache);
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}
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static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp)
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{
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struct zswap_entry *entry;
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entry = kmem_cache_alloc(zswap_entry_cache, gfp);
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if (!entry)
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return NULL;
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entry->refcount = 1;
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RB_CLEAR_NODE(&entry->rbnode);
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return entry;
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}
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static void zswap_entry_cache_free(struct zswap_entry *entry)
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{
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kmem_cache_free(zswap_entry_cache, entry);
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}
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/*********************************
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* rbtree functions
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**********************************/
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static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset)
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{
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struct rb_node *node = root->rb_node;
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struct zswap_entry *entry;
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while (node) {
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entry = rb_entry(node, struct zswap_entry, rbnode);
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if (entry->offset > offset)
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node = node->rb_left;
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else if (entry->offset < offset)
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node = node->rb_right;
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else
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return entry;
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}
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return NULL;
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}
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/*
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* In the case that a entry with the same offset is found, a pointer to
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* the existing entry is stored in dupentry and the function returns -EEXIST
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*/
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static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry,
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struct zswap_entry **dupentry)
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{
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struct rb_node **link = &root->rb_node, *parent = NULL;
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struct zswap_entry *myentry;
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while (*link) {
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parent = *link;
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myentry = rb_entry(parent, struct zswap_entry, rbnode);
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if (myentry->offset > entry->offset)
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link = &(*link)->rb_left;
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else if (myentry->offset < entry->offset)
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link = &(*link)->rb_right;
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else {
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*dupentry = myentry;
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return -EEXIST;
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}
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}
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rb_link_node(&entry->rbnode, parent, link);
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rb_insert_color(&entry->rbnode, root);
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return 0;
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}
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static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
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{
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if (!RB_EMPTY_NODE(&entry->rbnode)) {
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rb_erase(&entry->rbnode, root);
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RB_CLEAR_NODE(&entry->rbnode);
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}
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}
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/*
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* Carries out the common pattern of freeing and entry's zpool allocation,
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* freeing the entry itself, and decrementing the number of stored pages.
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*/
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static void zswap_free_entry(struct zswap_entry *entry)
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{
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zpool_free(zswap_pool, entry->handle);
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zswap_entry_cache_free(entry);
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atomic_dec(&zswap_stored_pages);
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zswap_pool_total_size = zpool_get_total_size(zswap_pool);
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}
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/* caller must hold the tree lock */
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static void zswap_entry_get(struct zswap_entry *entry)
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{
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entry->refcount++;
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}
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/* caller must hold the tree lock
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* remove from the tree and free it, if nobody reference the entry
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*/
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static void zswap_entry_put(struct zswap_tree *tree,
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struct zswap_entry *entry)
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{
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int refcount = --entry->refcount;
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BUG_ON(refcount < 0);
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if (refcount == 0) {
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zswap_rb_erase(&tree->rbroot, entry);
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zswap_free_entry(entry);
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}
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}
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/* caller must hold the tree lock */
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static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
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pgoff_t offset)
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{
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struct zswap_entry *entry = NULL;
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entry = zswap_rb_search(root, offset);
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if (entry)
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zswap_entry_get(entry);
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return entry;
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}
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/*********************************
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* per-cpu code
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**********************************/
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static DEFINE_PER_CPU(u8 *, zswap_dstmem);
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static int __zswap_cpu_notifier(unsigned long action, unsigned long cpu)
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{
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struct crypto_comp *tfm;
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u8 *dst;
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switch (action) {
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case CPU_UP_PREPARE:
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tfm = crypto_alloc_comp(zswap_compressor, 0, 0);
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if (IS_ERR(tfm)) {
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pr_err("can't allocate compressor transform\n");
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return NOTIFY_BAD;
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}
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*per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = tfm;
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dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
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if (!dst) {
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pr_err("can't allocate compressor buffer\n");
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crypto_free_comp(tfm);
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*per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = NULL;
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return NOTIFY_BAD;
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}
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per_cpu(zswap_dstmem, cpu) = dst;
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break;
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case CPU_DEAD:
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case CPU_UP_CANCELED:
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tfm = *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu);
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if (tfm) {
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crypto_free_comp(tfm);
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*per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = NULL;
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}
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dst = per_cpu(zswap_dstmem, cpu);
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kfree(dst);
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per_cpu(zswap_dstmem, cpu) = NULL;
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break;
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default:
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break;
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}
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return NOTIFY_OK;
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}
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static int zswap_cpu_notifier(struct notifier_block *nb,
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unsigned long action, void *pcpu)
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{
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unsigned long cpu = (unsigned long)pcpu;
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return __zswap_cpu_notifier(action, cpu);
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}
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static struct notifier_block zswap_cpu_notifier_block = {
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.notifier_call = zswap_cpu_notifier
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};
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static int zswap_cpu_init(void)
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{
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unsigned long cpu;
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cpu_notifier_register_begin();
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for_each_online_cpu(cpu)
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if (__zswap_cpu_notifier(CPU_UP_PREPARE, cpu) != NOTIFY_OK)
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goto cleanup;
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__register_cpu_notifier(&zswap_cpu_notifier_block);
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cpu_notifier_register_done();
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return 0;
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cleanup:
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for_each_online_cpu(cpu)
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__zswap_cpu_notifier(CPU_UP_CANCELED, cpu);
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cpu_notifier_register_done();
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return -ENOMEM;
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}
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/*********************************
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* helpers
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**********************************/
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static bool zswap_is_full(void)
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{
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return totalram_pages * zswap_max_pool_percent / 100 <
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DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
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}
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/*********************************
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* writeback code
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**********************************/
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/* return enum for zswap_get_swap_cache_page */
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enum zswap_get_swap_ret {
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ZSWAP_SWAPCACHE_NEW,
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ZSWAP_SWAPCACHE_EXIST,
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ZSWAP_SWAPCACHE_FAIL,
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};
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/*
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* zswap_get_swap_cache_page
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*
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* This is an adaption of read_swap_cache_async()
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*
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* This function tries to find a page with the given swap entry
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* in the swapper_space address space (the swap cache). If the page
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* is found, it is returned in retpage. Otherwise, a page is allocated,
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* added to the swap cache, and returned in retpage.
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*
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* If success, the swap cache page is returned in retpage
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* Returns ZSWAP_SWAPCACHE_EXIST if page was already in the swap cache
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* Returns ZSWAP_SWAPCACHE_NEW if the new page needs to be populated,
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* the new page is added to swapcache and locked
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* Returns ZSWAP_SWAPCACHE_FAIL on error
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*/
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static int zswap_get_swap_cache_page(swp_entry_t entry,
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struct page **retpage)
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{
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struct page *found_page, *new_page = NULL;
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struct address_space *swapper_space = swap_address_space(entry);
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int err;
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*retpage = NULL;
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do {
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/*
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* First check the swap cache. Since this is normally
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* called after lookup_swap_cache() failed, re-calling
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* that would confuse statistics.
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*/
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found_page = find_get_page(swapper_space, entry.val);
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if (found_page)
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break;
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/*
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* Get a new page to read into from swap.
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*/
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if (!new_page) {
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new_page = alloc_page(GFP_KERNEL);
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if (!new_page)
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break; /* Out of memory */
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}
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/*
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* call radix_tree_preload() while we can wait.
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*/
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err = radix_tree_preload(GFP_KERNEL);
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if (err)
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break;
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/*
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* Swap entry may have been freed since our caller observed it.
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*/
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err = swapcache_prepare(entry);
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if (err == -EEXIST) { /* seems racy */
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radix_tree_preload_end();
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continue;
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}
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if (err) { /* swp entry is obsolete ? */
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radix_tree_preload_end();
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break;
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}
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/* May fail (-ENOMEM) if radix-tree node allocation failed. */
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__set_page_locked(new_page);
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SetPageSwapBacked(new_page);
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err = __add_to_swap_cache(new_page, entry);
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if (likely(!err)) {
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radix_tree_preload_end();
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lru_cache_add_anon(new_page);
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*retpage = new_page;
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return ZSWAP_SWAPCACHE_NEW;
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}
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radix_tree_preload_end();
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ClearPageSwapBacked(new_page);
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__clear_page_locked(new_page);
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/*
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* add_to_swap_cache() doesn't return -EEXIST, so we can safely
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* clear SWAP_HAS_CACHE flag.
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*/
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swapcache_free(entry);
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} while (err != -ENOMEM);
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if (new_page)
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page_cache_release(new_page);
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if (!found_page)
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return ZSWAP_SWAPCACHE_FAIL;
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*retpage = found_page;
|
|
return ZSWAP_SWAPCACHE_EXIST;
|
|
}
|
|
|
|
/*
|
|
* Attempts to free an entry by adding a page to the swap cache,
|
|
* decompressing the entry data into the page, and issuing a
|
|
* bio write to write the page back to the swap device.
|
|
*
|
|
* This can be thought of as a "resumed writeback" of the page
|
|
* to the swap device. We are basically resuming the same swap
|
|
* writeback path that was intercepted with the frontswap_store()
|
|
* in the first place. After the page has been decompressed into
|
|
* the swap cache, the compressed version stored by zswap can be
|
|
* freed.
|
|
*/
|
|
static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
|
|
{
|
|
struct zswap_header *zhdr;
|
|
swp_entry_t swpentry;
|
|
struct zswap_tree *tree;
|
|
pgoff_t offset;
|
|
struct zswap_entry *entry;
|
|
struct page *page;
|
|
u8 *src, *dst;
|
|
unsigned int dlen;
|
|
int ret;
|
|
struct writeback_control wbc = {
|
|
.sync_mode = WB_SYNC_NONE,
|
|
};
|
|
|
|
/* extract swpentry from data */
|
|
zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO);
|
|
swpentry = zhdr->swpentry; /* here */
|
|
zpool_unmap_handle(pool, handle);
|
|
tree = zswap_trees[swp_type(swpentry)];
|
|
offset = swp_offset(swpentry);
|
|
|
|
/* find and ref zswap entry */
|
|
spin_lock(&tree->lock);
|
|
entry = zswap_entry_find_get(&tree->rbroot, offset);
|
|
if (!entry) {
|
|
/* entry was invalidated */
|
|
spin_unlock(&tree->lock);
|
|
return 0;
|
|
}
|
|
spin_unlock(&tree->lock);
|
|
BUG_ON(offset != entry->offset);
|
|
|
|
/* try to allocate swap cache page */
|
|
switch (zswap_get_swap_cache_page(swpentry, &page)) {
|
|
case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */
|
|
ret = -ENOMEM;
|
|
goto fail;
|
|
|
|
case ZSWAP_SWAPCACHE_EXIST:
|
|
/* page is already in the swap cache, ignore for now */
|
|
page_cache_release(page);
|
|
ret = -EEXIST;
|
|
goto fail;
|
|
|
|
case ZSWAP_SWAPCACHE_NEW: /* page is locked */
|
|
/* decompress */
|
|
dlen = PAGE_SIZE;
|
|
src = (u8 *)zpool_map_handle(zswap_pool, entry->handle,
|
|
ZPOOL_MM_RO) + sizeof(struct zswap_header);
|
|
dst = kmap_atomic(page);
|
|
ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src,
|
|
entry->length, dst, &dlen);
|
|
kunmap_atomic(dst);
|
|
zpool_unmap_handle(zswap_pool, entry->handle);
|
|
BUG_ON(ret);
|
|
BUG_ON(dlen != PAGE_SIZE);
|
|
|
|
/* page is up to date */
|
|
SetPageUptodate(page);
|
|
}
|
|
|
|
/* move it to the tail of the inactive list after end_writeback */
|
|
SetPageReclaim(page);
|
|
|
|
/* start writeback */
|
|
__swap_writepage(page, &wbc, end_swap_bio_write);
|
|
page_cache_release(page);
|
|
zswap_written_back_pages++;
|
|
|
|
spin_lock(&tree->lock);
|
|
/* drop local reference */
|
|
zswap_entry_put(tree, entry);
|
|
|
|
/*
|
|
* There are two possible situations for entry here:
|
|
* (1) refcount is 1(normal case), entry is valid and on the tree
|
|
* (2) refcount is 0, entry is freed and not on the tree
|
|
* because invalidate happened during writeback
|
|
* search the tree and free the entry if find entry
|
|
*/
|
|
if (entry == zswap_rb_search(&tree->rbroot, offset))
|
|
zswap_entry_put(tree, entry);
|
|
spin_unlock(&tree->lock);
|
|
|
|
goto end;
|
|
|
|
/*
|
|
* if we get here due to ZSWAP_SWAPCACHE_EXIST
|
|
* a load may happening concurrently
|
|
* it is safe and okay to not free the entry
|
|
* if we free the entry in the following put
|
|
* it it either okay to return !0
|
|
*/
|
|
fail:
|
|
spin_lock(&tree->lock);
|
|
zswap_entry_put(tree, entry);
|
|
spin_unlock(&tree->lock);
|
|
|
|
end:
|
|
return ret;
|
|
}
|
|
|
|
/*********************************
|
|
* frontswap hooks
|
|
**********************************/
|
|
/* attempts to compress and store an single page */
|
|
static int zswap_frontswap_store(unsigned type, pgoff_t offset,
|
|
struct page *page)
|
|
{
|
|
struct zswap_tree *tree = zswap_trees[type];
|
|
struct zswap_entry *entry, *dupentry;
|
|
int ret;
|
|
unsigned int dlen = PAGE_SIZE, len;
|
|
unsigned long handle;
|
|
char *buf;
|
|
u8 *src, *dst;
|
|
struct zswap_header *zhdr;
|
|
|
|
if (!tree) {
|
|
ret = -ENODEV;
|
|
goto reject;
|
|
}
|
|
|
|
/* reclaim space if needed */
|
|
if (zswap_is_full()) {
|
|
zswap_pool_limit_hit++;
|
|
if (zpool_shrink(zswap_pool, 1, NULL)) {
|
|
zswap_reject_reclaim_fail++;
|
|
ret = -ENOMEM;
|
|
goto reject;
|
|
}
|
|
}
|
|
|
|
/* allocate entry */
|
|
entry = zswap_entry_cache_alloc(GFP_KERNEL);
|
|
if (!entry) {
|
|
zswap_reject_kmemcache_fail++;
|
|
ret = -ENOMEM;
|
|
goto reject;
|
|
}
|
|
|
|
/* compress */
|
|
dst = get_cpu_var(zswap_dstmem);
|
|
src = kmap_atomic(page);
|
|
ret = zswap_comp_op(ZSWAP_COMPOP_COMPRESS, src, PAGE_SIZE, dst, &dlen);
|
|
kunmap_atomic(src);
|
|
if (ret) {
|
|
ret = -EINVAL;
|
|
goto freepage;
|
|
}
|
|
|
|
/* store */
|
|
len = dlen + sizeof(struct zswap_header);
|
|
ret = zpool_malloc(zswap_pool, len, __GFP_NORETRY | __GFP_NOWARN,
|
|
&handle);
|
|
if (ret == -ENOSPC) {
|
|
zswap_reject_compress_poor++;
|
|
goto freepage;
|
|
}
|
|
if (ret) {
|
|
zswap_reject_alloc_fail++;
|
|
goto freepage;
|
|
}
|
|
zhdr = zpool_map_handle(zswap_pool, handle, ZPOOL_MM_RW);
|
|
zhdr->swpentry = swp_entry(type, offset);
|
|
buf = (u8 *)(zhdr + 1);
|
|
memcpy(buf, dst, dlen);
|
|
zpool_unmap_handle(zswap_pool, handle);
|
|
put_cpu_var(zswap_dstmem);
|
|
|
|
/* populate entry */
|
|
entry->offset = offset;
|
|
entry->handle = handle;
|
|
entry->length = dlen;
|
|
|
|
/* map */
|
|
spin_lock(&tree->lock);
|
|
do {
|
|
ret = zswap_rb_insert(&tree->rbroot, entry, &dupentry);
|
|
if (ret == -EEXIST) {
|
|
zswap_duplicate_entry++;
|
|
/* remove from rbtree */
|
|
zswap_rb_erase(&tree->rbroot, dupentry);
|
|
zswap_entry_put(tree, dupentry);
|
|
}
|
|
} while (ret == -EEXIST);
|
|
spin_unlock(&tree->lock);
|
|
|
|
/* update stats */
|
|
atomic_inc(&zswap_stored_pages);
|
|
zswap_pool_total_size = zpool_get_total_size(zswap_pool);
|
|
|
|
return 0;
|
|
|
|
freepage:
|
|
put_cpu_var(zswap_dstmem);
|
|
zswap_entry_cache_free(entry);
|
|
reject:
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* returns 0 if the page was successfully decompressed
|
|
* return -1 on entry not found or error
|
|
*/
|
|
static int zswap_frontswap_load(unsigned type, pgoff_t offset,
|
|
struct page *page)
|
|
{
|
|
struct zswap_tree *tree = zswap_trees[type];
|
|
struct zswap_entry *entry;
|
|
u8 *src, *dst;
|
|
unsigned int dlen;
|
|
int ret;
|
|
|
|
/* find */
|
|
spin_lock(&tree->lock);
|
|
entry = zswap_entry_find_get(&tree->rbroot, offset);
|
|
if (!entry) {
|
|
/* entry was written back */
|
|
spin_unlock(&tree->lock);
|
|
return -1;
|
|
}
|
|
spin_unlock(&tree->lock);
|
|
|
|
/* decompress */
|
|
dlen = PAGE_SIZE;
|
|
src = (u8 *)zpool_map_handle(zswap_pool, entry->handle,
|
|
ZPOOL_MM_RO) + sizeof(struct zswap_header);
|
|
dst = kmap_atomic(page);
|
|
ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src, entry->length,
|
|
dst, &dlen);
|
|
kunmap_atomic(dst);
|
|
zpool_unmap_handle(zswap_pool, entry->handle);
|
|
BUG_ON(ret);
|
|
|
|
spin_lock(&tree->lock);
|
|
zswap_entry_put(tree, entry);
|
|
spin_unlock(&tree->lock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* frees an entry in zswap */
|
|
static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset)
|
|
{
|
|
struct zswap_tree *tree = zswap_trees[type];
|
|
struct zswap_entry *entry;
|
|
|
|
/* find */
|
|
spin_lock(&tree->lock);
|
|
entry = zswap_rb_search(&tree->rbroot, offset);
|
|
if (!entry) {
|
|
/* entry was written back */
|
|
spin_unlock(&tree->lock);
|
|
return;
|
|
}
|
|
|
|
/* remove from rbtree */
|
|
zswap_rb_erase(&tree->rbroot, entry);
|
|
|
|
/* drop the initial reference from entry creation */
|
|
zswap_entry_put(tree, entry);
|
|
|
|
spin_unlock(&tree->lock);
|
|
}
|
|
|
|
/* frees all zswap entries for the given swap type */
|
|
static void zswap_frontswap_invalidate_area(unsigned type)
|
|
{
|
|
struct zswap_tree *tree = zswap_trees[type];
|
|
struct zswap_entry *entry, *n;
|
|
|
|
if (!tree)
|
|
return;
|
|
|
|
/* walk the tree and free everything */
|
|
spin_lock(&tree->lock);
|
|
rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode)
|
|
zswap_free_entry(entry);
|
|
tree->rbroot = RB_ROOT;
|
|
spin_unlock(&tree->lock);
|
|
kfree(tree);
|
|
zswap_trees[type] = NULL;
|
|
}
|
|
|
|
static struct zpool_ops zswap_zpool_ops = {
|
|
.evict = zswap_writeback_entry
|
|
};
|
|
|
|
static void zswap_frontswap_init(unsigned type)
|
|
{
|
|
struct zswap_tree *tree;
|
|
|
|
tree = kzalloc(sizeof(struct zswap_tree), GFP_KERNEL);
|
|
if (!tree) {
|
|
pr_err("alloc failed, zswap disabled for swap type %d\n", type);
|
|
return;
|
|
}
|
|
|
|
tree->rbroot = RB_ROOT;
|
|
spin_lock_init(&tree->lock);
|
|
zswap_trees[type] = tree;
|
|
}
|
|
|
|
static struct frontswap_ops zswap_frontswap_ops = {
|
|
.store = zswap_frontswap_store,
|
|
.load = zswap_frontswap_load,
|
|
.invalidate_page = zswap_frontswap_invalidate_page,
|
|
.invalidate_area = zswap_frontswap_invalidate_area,
|
|
.init = zswap_frontswap_init
|
|
};
|
|
|
|
/*********************************
|
|
* debugfs functions
|
|
**********************************/
|
|
#ifdef CONFIG_DEBUG_FS
|
|
#include <linux/debugfs.h>
|
|
|
|
static struct dentry *zswap_debugfs_root;
|
|
|
|
static int __init zswap_debugfs_init(void)
|
|
{
|
|
if (!debugfs_initialized())
|
|
return -ENODEV;
|
|
|
|
zswap_debugfs_root = debugfs_create_dir("zswap", NULL);
|
|
if (!zswap_debugfs_root)
|
|
return -ENOMEM;
|
|
|
|
debugfs_create_u64("pool_limit_hit", S_IRUGO,
|
|
zswap_debugfs_root, &zswap_pool_limit_hit);
|
|
debugfs_create_u64("reject_reclaim_fail", S_IRUGO,
|
|
zswap_debugfs_root, &zswap_reject_reclaim_fail);
|
|
debugfs_create_u64("reject_alloc_fail", S_IRUGO,
|
|
zswap_debugfs_root, &zswap_reject_alloc_fail);
|
|
debugfs_create_u64("reject_kmemcache_fail", S_IRUGO,
|
|
zswap_debugfs_root, &zswap_reject_kmemcache_fail);
|
|
debugfs_create_u64("reject_compress_poor", S_IRUGO,
|
|
zswap_debugfs_root, &zswap_reject_compress_poor);
|
|
debugfs_create_u64("written_back_pages", S_IRUGO,
|
|
zswap_debugfs_root, &zswap_written_back_pages);
|
|
debugfs_create_u64("duplicate_entry", S_IRUGO,
|
|
zswap_debugfs_root, &zswap_duplicate_entry);
|
|
debugfs_create_u64("pool_total_size", S_IRUGO,
|
|
zswap_debugfs_root, &zswap_pool_total_size);
|
|
debugfs_create_atomic_t("stored_pages", S_IRUGO,
|
|
zswap_debugfs_root, &zswap_stored_pages);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __exit zswap_debugfs_exit(void)
|
|
{
|
|
debugfs_remove_recursive(zswap_debugfs_root);
|
|
}
|
|
#else
|
|
static int __init zswap_debugfs_init(void)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static void __exit zswap_debugfs_exit(void) { }
|
|
#endif
|
|
|
|
/*********************************
|
|
* module init and exit
|
|
**********************************/
|
|
static int __init init_zswap(void)
|
|
{
|
|
gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN;
|
|
|
|
if (!zswap_enabled)
|
|
return 0;
|
|
|
|
pr_info("loading zswap\n");
|
|
|
|
zswap_pool = zpool_create_pool(zswap_zpool_type, gfp, &zswap_zpool_ops);
|
|
if (!zswap_pool && strcmp(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT)) {
|
|
pr_info("%s zpool not available\n", zswap_zpool_type);
|
|
zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
|
|
zswap_pool = zpool_create_pool(zswap_zpool_type, gfp,
|
|
&zswap_zpool_ops);
|
|
}
|
|
if (!zswap_pool) {
|
|
pr_err("%s zpool not available\n", zswap_zpool_type);
|
|
pr_err("zpool creation failed\n");
|
|
goto error;
|
|
}
|
|
pr_info("using %s pool\n", zswap_zpool_type);
|
|
|
|
if (zswap_entry_cache_create()) {
|
|
pr_err("entry cache creation failed\n");
|
|
goto cachefail;
|
|
}
|
|
if (zswap_comp_init()) {
|
|
pr_err("compressor initialization failed\n");
|
|
goto compfail;
|
|
}
|
|
if (zswap_cpu_init()) {
|
|
pr_err("per-cpu initialization failed\n");
|
|
goto pcpufail;
|
|
}
|
|
|
|
frontswap_register_ops(&zswap_frontswap_ops);
|
|
if (zswap_debugfs_init())
|
|
pr_warn("debugfs initialization failed\n");
|
|
return 0;
|
|
pcpufail:
|
|
zswap_comp_exit();
|
|
compfail:
|
|
zswap_entry_cache_destroy();
|
|
cachefail:
|
|
zpool_destroy_pool(zswap_pool);
|
|
error:
|
|
return -ENOMEM;
|
|
}
|
|
/* must be late so crypto has time to come up */
|
|
late_initcall(init_zswap);
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("Seth Jennings <sjenning@linux.vnet.ibm.com>");
|
|
MODULE_DESCRIPTION("Compressed cache for swap pages");
|
|
|