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290 lines
6.4 KiB
290 lines
6.4 KiB
/*
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* Copyright (C) 2001-2002 Sistina Software (UK) Limited.
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* Copyright (C) 2006-2008 Red Hat GmbH
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*
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* This file is released under the GPL.
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*/
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#include "dm-exception-store.h"
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#include <linux/ctype.h>
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#include <linux/mm.h>
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#include <linux/pagemap.h>
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#include <linux/vmalloc.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#define DM_MSG_PREFIX "snapshot exception stores"
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static LIST_HEAD(_exception_store_types);
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static DEFINE_SPINLOCK(_lock);
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static struct dm_exception_store_type *__find_exception_store_type(const char *name)
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{
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struct dm_exception_store_type *type;
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list_for_each_entry(type, &_exception_store_types, list)
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if (!strcmp(name, type->name))
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return type;
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return NULL;
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}
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static struct dm_exception_store_type *_get_exception_store_type(const char *name)
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{
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struct dm_exception_store_type *type;
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spin_lock(&_lock);
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type = __find_exception_store_type(name);
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if (type && !try_module_get(type->module))
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type = NULL;
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spin_unlock(&_lock);
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return type;
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}
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/*
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* get_type
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* @type_name
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*
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* Attempt to retrieve the dm_exception_store_type by name. If not already
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* available, attempt to load the appropriate module.
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*
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* Exstore modules are named "dm-exstore-" followed by the 'type_name'.
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* Modules may contain multiple types.
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* This function will first try the module "dm-exstore-<type_name>",
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* then truncate 'type_name' on the last '-' and try again.
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*
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* For example, if type_name was "clustered-shared", it would search
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* 'dm-exstore-clustered-shared' then 'dm-exstore-clustered'.
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*
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* 'dm-exception-store-<type_name>' is too long of a name in my
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* opinion, which is why I've chosen to have the files
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* containing exception store implementations be 'dm-exstore-<type_name>'.
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* If you want your module to be autoloaded, you will follow this
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* naming convention.
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*
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* Returns: dm_exception_store_type* on success, NULL on failure
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*/
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static struct dm_exception_store_type *get_type(const char *type_name)
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{
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char *p, *type_name_dup;
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struct dm_exception_store_type *type;
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type = _get_exception_store_type(type_name);
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if (type)
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return type;
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type_name_dup = kstrdup(type_name, GFP_KERNEL);
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if (!type_name_dup) {
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DMERR("No memory left to attempt load for \"%s\"", type_name);
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return NULL;
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}
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while (request_module("dm-exstore-%s", type_name_dup) ||
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!(type = _get_exception_store_type(type_name))) {
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p = strrchr(type_name_dup, '-');
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if (!p)
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break;
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p[0] = '\0';
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}
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if (!type)
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DMWARN("Module for exstore type \"%s\" not found.", type_name);
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kfree(type_name_dup);
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return type;
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}
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static void put_type(struct dm_exception_store_type *type)
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{
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spin_lock(&_lock);
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module_put(type->module);
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spin_unlock(&_lock);
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}
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int dm_exception_store_type_register(struct dm_exception_store_type *type)
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{
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int r = 0;
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spin_lock(&_lock);
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if (!__find_exception_store_type(type->name))
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list_add(&type->list, &_exception_store_types);
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else
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r = -EEXIST;
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spin_unlock(&_lock);
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return r;
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}
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EXPORT_SYMBOL(dm_exception_store_type_register);
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int dm_exception_store_type_unregister(struct dm_exception_store_type *type)
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{
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spin_lock(&_lock);
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if (!__find_exception_store_type(type->name)) {
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spin_unlock(&_lock);
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return -EINVAL;
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}
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list_del(&type->list);
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spin_unlock(&_lock);
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return 0;
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}
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EXPORT_SYMBOL(dm_exception_store_type_unregister);
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static int set_chunk_size(struct dm_exception_store *store,
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const char *chunk_size_arg, char **error)
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{
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unsigned chunk_size;
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if (kstrtouint(chunk_size_arg, 10, &chunk_size)) {
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*error = "Invalid chunk size";
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return -EINVAL;
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}
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if (!chunk_size) {
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store->chunk_size = store->chunk_mask = store->chunk_shift = 0;
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return 0;
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}
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return dm_exception_store_set_chunk_size(store, chunk_size, error);
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}
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int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
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unsigned chunk_size,
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char **error)
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{
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/* Check chunk_size is a power of 2 */
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if (!is_power_of_2(chunk_size)) {
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*error = "Chunk size is not a power of 2";
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return -EINVAL;
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}
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/* Validate the chunk size against the device block size */
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if (chunk_size %
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(bdev_logical_block_size(dm_snap_cow(store->snap)->bdev) >> 9) ||
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chunk_size %
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(bdev_logical_block_size(dm_snap_origin(store->snap)->bdev) >> 9)) {
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*error = "Chunk size is not a multiple of device blocksize";
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return -EINVAL;
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}
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if (chunk_size > INT_MAX >> SECTOR_SHIFT) {
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*error = "Chunk size is too high";
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return -EINVAL;
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}
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store->chunk_size = chunk_size;
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store->chunk_mask = chunk_size - 1;
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store->chunk_shift = ffs(chunk_size) - 1;
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return 0;
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}
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int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
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struct dm_snapshot *snap,
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unsigned *args_used,
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struct dm_exception_store **store)
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{
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int r = 0;
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struct dm_exception_store_type *type = NULL;
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struct dm_exception_store *tmp_store;
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char persistent;
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if (argc < 2) {
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ti->error = "Insufficient exception store arguments";
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return -EINVAL;
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}
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tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL);
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if (!tmp_store) {
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ti->error = "Exception store allocation failed";
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return -ENOMEM;
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}
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persistent = toupper(*argv[0]);
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if (persistent == 'P')
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type = get_type("P");
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else if (persistent == 'N')
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type = get_type("N");
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else {
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ti->error = "Persistent flag is not P or N";
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r = -EINVAL;
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goto bad_type;
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}
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if (!type) {
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ti->error = "Exception store type not recognised";
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r = -EINVAL;
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goto bad_type;
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}
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tmp_store->type = type;
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tmp_store->snap = snap;
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r = set_chunk_size(tmp_store, argv[1], &ti->error);
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if (r)
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goto bad;
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r = type->ctr(tmp_store, 0, NULL);
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if (r) {
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ti->error = "Exception store type constructor failed";
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goto bad;
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}
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*args_used = 2;
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*store = tmp_store;
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return 0;
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bad:
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put_type(type);
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bad_type:
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kfree(tmp_store);
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return r;
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}
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EXPORT_SYMBOL(dm_exception_store_create);
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void dm_exception_store_destroy(struct dm_exception_store *store)
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{
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store->type->dtr(store);
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put_type(store->type);
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kfree(store);
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}
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EXPORT_SYMBOL(dm_exception_store_destroy);
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int dm_exception_store_init(void)
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{
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int r;
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r = dm_transient_snapshot_init();
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if (r) {
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DMERR("Unable to register transient exception store type.");
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goto transient_fail;
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}
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r = dm_persistent_snapshot_init();
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if (r) {
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DMERR("Unable to register persistent exception store type");
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goto persistent_fail;
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}
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return 0;
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persistent_fail:
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dm_transient_snapshot_exit();
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transient_fail:
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return r;
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}
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void dm_exception_store_exit(void)
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{
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dm_persistent_snapshot_exit();
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dm_transient_snapshot_exit();
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}
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