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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); |
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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 = kzalloc(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 = "Exception store type 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, (strlen(argv[0]) > 1 ? &argv[0][1] : 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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