Author | Tokens | Token Proportion | Commits | Commit Proportion |
---|---|---|---|---|
Joe Thornber | 7210 | 90.12% | 29 | 56.86% |
Mike Snitzer | 698 | 8.72% | 13 | 25.49% |
Nikos Tsironis | 29 | 0.36% | 1 | 1.96% |
Ilya Dryomov | 26 | 0.33% | 1 | 1.96% |
Ye Bin | 19 | 0.24% | 1 | 1.96% |
Elena Reshetova | 7 | 0.09% | 1 | 1.96% |
Mikulas Patocka | 6 | 0.07% | 1 | 1.96% |
Christoph Hellwig | 2 | 0.03% | 2 | 3.92% |
Ahmed Samy | 2 | 0.03% | 1 | 1.96% |
Guo Zhengkui | 1 | 0.01% | 1 | 1.96% |
Total | 8000 | 51 |
/* * Copyright (C) 2012 Red Hat, Inc. * * This file is released under the GPL. */ #include "dm-cache-metadata.h" #include "persistent-data/dm-array.h" #include "persistent-data/dm-bitset.h" #include "persistent-data/dm-space-map.h" #include "persistent-data/dm-space-map-disk.h" #include "persistent-data/dm-transaction-manager.h" #include <linux/device-mapper.h> #include <linux/refcount.h> /*----------------------------------------------------------------*/ #define DM_MSG_PREFIX "cache metadata" #define CACHE_SUPERBLOCK_MAGIC 06142003 #define CACHE_SUPERBLOCK_LOCATION 0 /* * defines a range of metadata versions that this module can handle. */ #define MIN_CACHE_VERSION 1 #define MAX_CACHE_VERSION 2 /* * 3 for btree insert + * 2 for btree lookup used within space map */ #define CACHE_MAX_CONCURRENT_LOCKS 5 #define SPACE_MAP_ROOT_SIZE 128 enum superblock_flag_bits { /* for spotting crashes that would invalidate the dirty bitset */ CLEAN_SHUTDOWN, /* metadata must be checked using the tools */ NEEDS_CHECK, }; /* * Each mapping from cache block -> origin block carries a set of flags. */ enum mapping_bits { /* * A valid mapping. Because we're using an array we clear this * flag for an non existant mapping. */ M_VALID = 1, /* * The data on the cache is different from that on the origin. * This flag is only used by metadata format 1. */ M_DIRTY = 2 }; struct cache_disk_superblock { __le32 csum; __le32 flags; __le64 blocknr; __u8 uuid[16]; __le64 magic; __le32 version; __u8 policy_name[CACHE_POLICY_NAME_SIZE]; __le32 policy_hint_size; __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE]; __le64 mapping_root; __le64 hint_root; __le64 discard_root; __le64 discard_block_size; __le64 discard_nr_blocks; __le32 data_block_size; __le32 metadata_block_size; __le32 cache_blocks; __le32 compat_flags; __le32 compat_ro_flags; __le32 incompat_flags; __le32 read_hits; __le32 read_misses; __le32 write_hits; __le32 write_misses; __le32 policy_version[CACHE_POLICY_VERSION_SIZE]; /* * Metadata format 2 fields. */ __le64 dirty_root; } __packed; struct dm_cache_metadata { refcount_t ref_count; struct list_head list; unsigned version; struct block_device *bdev; struct dm_block_manager *bm; struct dm_space_map *metadata_sm; struct dm_transaction_manager *tm; struct dm_array_info info; struct dm_array_info hint_info; struct dm_disk_bitset discard_info; struct rw_semaphore root_lock; unsigned long flags; dm_block_t root; dm_block_t hint_root; dm_block_t discard_root; sector_t discard_block_size; dm_dblock_t discard_nr_blocks; sector_t data_block_size; dm_cblock_t cache_blocks; bool changed:1; bool clean_when_opened:1; char policy_name[CACHE_POLICY_NAME_SIZE]; unsigned policy_version[CACHE_POLICY_VERSION_SIZE]; size_t policy_hint_size; struct dm_cache_statistics stats; /* * Reading the space map root can fail, so we read it into this * buffer before the superblock is locked and updated. */ __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE]; /* * Set if a transaction has to be aborted but the attempt to roll * back to the previous (good) transaction failed. The only * metadata operation permissible in this state is the closing of * the device. */ bool fail_io:1; /* * Metadata format 2 fields. */ dm_block_t dirty_root; struct dm_disk_bitset dirty_info; /* * These structures are used when loading metadata. They're too * big to put on the stack. */ struct dm_array_cursor mapping_cursor; struct dm_array_cursor hint_cursor; struct dm_bitset_cursor dirty_cursor; }; /*------------------------------------------------------------------- * superblock validator *-----------------------------------------------------------------*/ #define SUPERBLOCK_CSUM_XOR 9031977 static void sb_prepare_for_write(struct dm_block_validator *v, struct dm_block *b, size_t sb_block_size) { struct cache_disk_superblock *disk_super = dm_block_data(b); disk_super->blocknr = cpu_to_le64(dm_block_location(b)); disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags, sb_block_size - sizeof(__le32), SUPERBLOCK_CSUM_XOR)); } static int check_metadata_version(struct cache_disk_superblock *disk_super) { uint32_t metadata_version = le32_to_cpu(disk_super->version); if (metadata_version < MIN_CACHE_VERSION || metadata_version > MAX_CACHE_VERSION) { DMERR("Cache metadata version %u found, but only versions between %u and %u supported.", metadata_version, MIN_CACHE_VERSION, MAX_CACHE_VERSION); return -EINVAL; } return 0; } static int sb_check(struct dm_block_validator *v, struct dm_block *b, size_t sb_block_size) { struct cache_disk_superblock *disk_super = dm_block_data(b); __le32 csum_le; if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) { DMERR("sb_check failed: blocknr %llu: wanted %llu", le64_to_cpu(disk_super->blocknr), (unsigned long long)dm_block_location(b)); return -ENOTBLK; } if (le64_to_cpu(disk_super->magic) != CACHE_SUPERBLOCK_MAGIC) { DMERR("sb_check failed: magic %llu: wanted %llu", le64_to_cpu(disk_super->magic), (unsigned long long)CACHE_SUPERBLOCK_MAGIC); return -EILSEQ; } csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags, sb_block_size - sizeof(__le32), SUPERBLOCK_CSUM_XOR)); if (csum_le != disk_super->csum) { DMERR("sb_check failed: csum %u: wanted %u", le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum)); return -EILSEQ; } return check_metadata_version(disk_super); } static struct dm_block_validator sb_validator = { .name = "superblock", .prepare_for_write = sb_prepare_for_write, .check = sb_check }; /*----------------------------------------------------------------*/ static int superblock_read_lock(struct dm_cache_metadata *cmd, struct dm_block **sblock) { return dm_bm_read_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION, &sb_validator, sblock); } static int superblock_lock_zero(struct dm_cache_metadata *cmd, struct dm_block **sblock) { return dm_bm_write_lock_zero(cmd->bm, CACHE_SUPERBLOCK_LOCATION, &sb_validator, sblock); } static int superblock_lock(struct dm_cache_metadata *cmd, struct dm_block **sblock) { return dm_bm_write_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION, &sb_validator, sblock); } /*----------------------------------------------------------------*/ static int __superblock_all_zeroes(struct dm_block_manager *bm, bool *result) { int r; unsigned i; struct dm_block *b; __le64 *data_le, zero = cpu_to_le64(0); unsigned sb_block_size = dm_bm_block_size(bm) / sizeof(__le64); /* * We can't use a validator here - it may be all zeroes. */ r = dm_bm_read_lock(bm, CACHE_SUPERBLOCK_LOCATION, NULL, &b); if (r) return r; data_le = dm_block_data(b); *result = true; for (i = 0; i < sb_block_size; i++) { if (data_le[i] != zero) { *result = false; break; } } dm_bm_unlock(b); return 0; } static void __setup_mapping_info(struct dm_cache_metadata *cmd) { struct dm_btree_value_type vt; vt.context = NULL; vt.size = sizeof(__le64); vt.inc = NULL; vt.dec = NULL; vt.equal = NULL; dm_array_info_init(&cmd->info, cmd->tm, &vt); if (cmd->policy_hint_size) { vt.size = sizeof(__le32); dm_array_info_init(&cmd->hint_info, cmd->tm, &vt); } } static int __save_sm_root(struct dm_cache_metadata *cmd) { int r; size_t metadata_len; r = dm_sm_root_size(cmd->metadata_sm, &metadata_len); if (r < 0) return r; return dm_sm_copy_root(cmd->metadata_sm, &cmd->metadata_space_map_root, metadata_len); } static void __copy_sm_root(struct dm_cache_metadata *cmd, struct cache_disk_superblock *disk_super) { memcpy(&disk_super->metadata_space_map_root, &cmd->metadata_space_map_root, sizeof(cmd->metadata_space_map_root)); } static bool separate_dirty_bits(struct dm_cache_metadata *cmd) { return cmd->version >= 2; } static int __write_initial_superblock(struct dm_cache_metadata *cmd) { int r; struct dm_block *sblock; struct cache_disk_superblock *disk_super; sector_t bdev_size = bdev_nr_sectors(cmd->bdev); /* FIXME: see if we can lose the max sectors limit */ if (bdev_size > DM_CACHE_METADATA_MAX_SECTORS) bdev_size = DM_CACHE_METADATA_MAX_SECTORS; r = dm_tm_pre_commit(cmd->tm); if (r < 0) return r; /* * dm_sm_copy_root() can fail. So we need to do it before we start * updating the superblock. */ r = __save_sm_root(cmd); if (r) return r; r = superblock_lock_zero(cmd, &sblock); if (r) return r; disk_super = dm_block_data(sblock); disk_super->flags = 0; memset(disk_super->uuid, 0, sizeof(disk_super->uuid)); disk_super->magic = cpu_to_le64(CACHE_SUPERBLOCK_MAGIC); disk_super->version = cpu_to_le32(cmd->version); memset(disk_super->policy_name, 0, sizeof(disk_super->policy_name)); memset(disk_super->policy_version, 0, sizeof(disk_super->policy_version)); disk_super->policy_hint_size = cpu_to_le32(0); __copy_sm_root(cmd, disk_super); disk_super->mapping_root = cpu_to_le64(cmd->root); disk_super->hint_root = cpu_to_le64(cmd->hint_root); disk_super->discard_root = cpu_to_le64(cmd->discard_root); disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size); disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks)); disk_super->metadata_block_size = cpu_to_le32(DM_CACHE_METADATA_BLOCK_SIZE); disk_super->data_block_size = cpu_to_le32(cmd->data_block_size); disk_super->cache_blocks = cpu_to_le32(0); disk_super->read_hits = cpu_to_le32(0); disk_super->read_misses = cpu_to_le32(0); disk_super->write_hits = cpu_to_le32(0); disk_super->write_misses = cpu_to_le32(0); if (separate_dirty_bits(cmd)) disk_super->dirty_root = cpu_to_le64(cmd->dirty_root); return dm_tm_commit(cmd->tm, sblock); } static int __format_metadata(struct dm_cache_metadata *cmd) { int r; r = dm_tm_create_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION, &cmd->tm, &cmd->metadata_sm); if (r < 0) { DMERR("tm_create_with_sm failed"); return r; } __setup_mapping_info(cmd); r = dm_array_empty(&cmd->info, &cmd->root); if (r < 0) goto bad; if (separate_dirty_bits(cmd)) { dm_disk_bitset_init(cmd->tm, &cmd->dirty_info); r = dm_bitset_empty(&cmd->dirty_info, &cmd->dirty_root); if (r < 0) goto bad; } dm_disk_bitset_init(cmd->tm, &cmd->discard_info); r = dm_bitset_empty(&cmd->discard_info, &cmd->discard_root); if (r < 0) goto bad; cmd->discard_block_size = 0; cmd->discard_nr_blocks = 0; r = __write_initial_superblock(cmd); if (r) goto bad; cmd->clean_when_opened = true; return 0; bad: dm_tm_destroy(cmd->tm); dm_sm_destroy(cmd->metadata_sm); return r; } static int __check_incompat_features(struct cache_disk_superblock *disk_super, struct dm_cache_metadata *cmd) { uint32_t incompat_flags, features; incompat_flags = le32_to_cpu(disk_super->incompat_flags); features = incompat_flags & ~DM_CACHE_FEATURE_INCOMPAT_SUPP; if (features) { DMERR("could not access metadata due to unsupported optional features (%lx).", (unsigned long)features); return -EINVAL; } /* * Check for read-only metadata to skip the following RDWR checks. */ if (bdev_read_only(cmd->bdev)) return 0; features = le32_to_cpu(disk_super->compat_ro_flags) & ~DM_CACHE_FEATURE_COMPAT_RO_SUPP; if (features) { DMERR("could not access metadata RDWR due to unsupported optional features (%lx).", (unsigned long)features); return -EINVAL; } return 0; } static int __open_metadata(struct dm_cache_metadata *cmd) { int r; struct dm_block *sblock; struct cache_disk_superblock *disk_super; unsigned long sb_flags; r = superblock_read_lock(cmd, &sblock); if (r < 0) { DMERR("couldn't read lock superblock"); return r; } disk_super = dm_block_data(sblock); /* Verify the data block size hasn't changed */ if (le32_to_cpu(disk_super->data_block_size) != cmd->data_block_size) { DMERR("changing the data block size (from %u to %llu) is not supported", le32_to_cpu(disk_super->data_block_size), (unsigned long long)cmd->data_block_size); r = -EINVAL; goto bad; } r = __check_incompat_features(disk_super, cmd); if (r < 0) goto bad; r = dm_tm_open_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION, disk_super->metadata_space_map_root, sizeof(disk_super->metadata_space_map_root), &cmd->tm, &cmd->metadata_sm); if (r < 0) { DMERR("tm_open_with_sm failed"); goto bad; } __setup_mapping_info(cmd); dm_disk_bitset_init(cmd->tm, &cmd->dirty_info); dm_disk_bitset_init(cmd->tm, &cmd->discard_info); sb_flags = le32_to_cpu(disk_super->flags); cmd->clean_when_opened = test_bit(CLEAN_SHUTDOWN, &sb_flags); dm_bm_unlock(sblock); return 0; bad: dm_bm_unlock(sblock); return r; } static int __open_or_format_metadata(struct dm_cache_metadata *cmd, bool format_device) { int r; bool unformatted = false; r = __superblock_all_zeroes(cmd->bm, &unformatted); if (r) return r; if (unformatted) return format_device ? __format_metadata(cmd) : -EPERM; return __open_metadata(cmd); } static int __create_persistent_data_objects(struct dm_cache_metadata *cmd, bool may_format_device) { int r; cmd->bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT, CACHE_MAX_CONCURRENT_LOCKS); if (IS_ERR(cmd->bm)) { DMERR("could not create block manager"); r = PTR_ERR(cmd->bm); cmd->bm = NULL; return r; } r = __open_or_format_metadata(cmd, may_format_device); if (r) { dm_block_manager_destroy(cmd->bm); cmd->bm = NULL; } return r; } static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd, bool destroy_bm) { dm_sm_destroy(cmd->metadata_sm); dm_tm_destroy(cmd->tm); if (destroy_bm) dm_block_manager_destroy(cmd->bm); } typedef unsigned long (*flags_mutator)(unsigned long); static void update_flags(struct cache_disk_superblock *disk_super, flags_mutator mutator) { uint32_t sb_flags = mutator(le32_to_cpu(disk_super->flags)); disk_super->flags = cpu_to_le32(sb_flags); } static unsigned long set_clean_shutdown(unsigned long flags) { set_bit(CLEAN_SHUTDOWN, &flags); return flags; } static unsigned long clear_clean_shutdown(unsigned long flags) { clear_bit(CLEAN_SHUTDOWN, &flags); return flags; } static void read_superblock_fields(struct dm_cache_metadata *cmd, struct cache_disk_superblock *disk_super) { cmd->version = le32_to_cpu(disk_super->version); cmd->flags = le32_to_cpu(disk_super->flags); cmd->root = le64_to_cpu(disk_super->mapping_root); cmd->hint_root = le64_to_cpu(disk_super->hint_root); cmd->discard_root = le64_to_cpu(disk_super->discard_root); cmd->discard_block_size = le64_to_cpu(disk_super->discard_block_size); cmd->discard_nr_blocks = to_dblock(le64_to_cpu(disk_super->discard_nr_blocks)); cmd->data_block_size = le32_to_cpu(disk_super->data_block_size); cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks)); strncpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name)); cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]); cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]); cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]); cmd->policy_hint_size = le32_to_cpu(disk_super->policy_hint_size); cmd->stats.read_hits = le32_to_cpu(disk_super->read_hits); cmd->stats.read_misses = le32_to_cpu(disk_super->read_misses); cmd->stats.write_hits = le32_to_cpu(disk_super->write_hits); cmd->stats.write_misses = le32_to_cpu(disk_super->write_misses); if (separate_dirty_bits(cmd)) cmd->dirty_root = le64_to_cpu(disk_super->dirty_root); cmd->changed = false; } /* * The mutator updates the superblock flags. */ static int __begin_transaction_flags(struct dm_cache_metadata *cmd, flags_mutator mutator) { int r; struct cache_disk_superblock *disk_super; struct dm_block *sblock; r = superblock_lock(cmd, &sblock); if (r) return r; disk_super = dm_block_data(sblock); update_flags(disk_super, mutator); read_superblock_fields(cmd, disk_super); dm_bm_unlock(sblock); return dm_bm_flush(cmd->bm); } static int __begin_transaction(struct dm_cache_metadata *cmd) { int r; struct cache_disk_superblock *disk_super; struct dm_block *sblock; /* * We re-read the superblock every time. Shouldn't need to do this * really. */ r = superblock_read_lock(cmd, &sblock); if (r) return r; disk_super = dm_block_data(sblock); read_superblock_fields(cmd, disk_super); dm_bm_unlock(sblock); return 0; } static int __commit_transaction(struct dm_cache_metadata *cmd, flags_mutator mutator) { int r; struct cache_disk_superblock *disk_super; struct dm_block *sblock; /* * We need to know if the cache_disk_superblock exceeds a 512-byte sector. */ BUILD_BUG_ON(sizeof(struct cache_disk_superblock) > 512); if (separate_dirty_bits(cmd)) { r = dm_bitset_flush(&cmd->dirty_info, cmd->dirty_root, &cmd->dirty_root); if (r) return r; } r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root, &cmd->discard_root); if (r) return r; r = dm_tm_pre_commit(cmd->tm); if (r < 0) return r; r = __save_sm_root(cmd); if (r) return r; r = superblock_lock(cmd, &sblock); if (r) return r; disk_super = dm_block_data(sblock); disk_super->flags = cpu_to_le32(cmd->flags); if (mutator) update_flags(disk_super, mutator); disk_super->mapping_root = cpu_to_le64(cmd->root); if (separate_dirty_bits(cmd)) disk_super->dirty_root = cpu_to_le64(cmd->dirty_root); disk_super->hint_root = cpu_to_le64(cmd->hint_root); disk_super->discard_root = cpu_to_le64(cmd->discard_root); disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size); disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks)); disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks)); strncpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name)); disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]); disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]); disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]); disk_super->policy_hint_size = cpu_to_le32(cmd->policy_hint_size); disk_super->read_hits = cpu_to_le32(cmd->stats.read_hits); disk_super->read_misses = cpu_to_le32(cmd->stats.read_misses); disk_super->write_hits = cpu_to_le32(cmd->stats.write_hits); disk_super->write_misses = cpu_to_le32(cmd->stats.write_misses); __copy_sm_root(cmd, disk_super); return dm_tm_commit(cmd->tm, sblock); } /*----------------------------------------------------------------*/ /* * The mappings are held in a dm-array that has 64-bit values stored in * little-endian format. The index is the cblock, the high 48bits of the * value are the oblock and the low 16 bit the flags. */ #define FLAGS_MASK ((1 << 16) - 1) static __le64 pack_value(dm_oblock_t block, unsigned flags) { uint64_t value = from_oblock(block); value <<= 16; value = value | (flags & FLAGS_MASK); return cpu_to_le64(value); } static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags) { uint64_t value = le64_to_cpu(value_le); uint64_t b = value >> 16; *block = to_oblock(b); *flags = value & FLAGS_MASK; } /*----------------------------------------------------------------*/ static struct dm_cache_metadata *metadata_open(struct block_device *bdev, sector_t data_block_size, bool may_format_device, size_t policy_hint_size, unsigned metadata_version) { int r; struct dm_cache_metadata *cmd; cmd = kzalloc(sizeof(*cmd), GFP_KERNEL); if (!cmd) { DMERR("could not allocate metadata struct"); return ERR_PTR(-ENOMEM); } cmd->version = metadata_version; refcount_set(&cmd->ref_count, 1); init_rwsem(&cmd->root_lock); cmd->bdev = bdev; cmd->data_block_size = data_block_size; cmd->cache_blocks = 0; cmd->policy_hint_size = policy_hint_size; cmd->changed = true; cmd->fail_io = false; r = __create_persistent_data_objects(cmd, may_format_device); if (r) { kfree(cmd); return ERR_PTR(r); } r = __begin_transaction_flags(cmd, clear_clean_shutdown); if (r < 0) { dm_cache_metadata_close(cmd); return ERR_PTR(r); } return cmd; } /* * We keep a little list of ref counted metadata objects to prevent two * different target instances creating separate bufio instances. This is * an issue if a table is reloaded before the suspend. */ static DEFINE_MUTEX(table_lock); static LIST_HEAD(table); static struct dm_cache_metadata *lookup(struct block_device *bdev) { struct dm_cache_metadata *cmd; list_for_each_entry(cmd, &table, list) if (cmd->bdev == bdev) { refcount_inc(&cmd->ref_count); return cmd; } return NULL; } static struct dm_cache_metadata *lookup_or_open(struct block_device *bdev, sector_t data_block_size, bool may_format_device, size_t policy_hint_size, unsigned metadata_version) { struct dm_cache_metadata *cmd, *cmd2; mutex_lock(&table_lock); cmd = lookup(bdev); mutex_unlock(&table_lock); if (cmd) return cmd; cmd = metadata_open(bdev, data_block_size, may_format_device, policy_hint_size, metadata_version); if (!IS_ERR(cmd)) { mutex_lock(&table_lock); cmd2 = lookup(bdev); if (cmd2) { mutex_unlock(&table_lock); __destroy_persistent_data_objects(cmd, true); kfree(cmd); return cmd2; } list_add(&cmd->list, &table); mutex_unlock(&table_lock); } return cmd; } static bool same_params(struct dm_cache_metadata *cmd, sector_t data_block_size) { if (cmd->data_block_size != data_block_size) { DMERR("data_block_size (%llu) different from that in metadata (%llu)", (unsigned long long) data_block_size, (unsigned long long) cmd->data_block_size); return false; } return true; } struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev, sector_t data_block_size, bool may_format_device, size_t policy_hint_size, unsigned metadata_version) { struct dm_cache_metadata *cmd = lookup_or_open(bdev, data_block_size, may_format_device, policy_hint_size, metadata_version); if (!IS_ERR(cmd) && !same_params(cmd, data_block_size)) { dm_cache_metadata_close(cmd); return ERR_PTR(-EINVAL); } return cmd; } void dm_cache_metadata_close(struct dm_cache_metadata *cmd) { if (refcount_dec_and_test(&cmd->ref_count)) { mutex_lock(&table_lock); list_del(&cmd->list); mutex_unlock(&table_lock); if (!cmd->fail_io) __destroy_persistent_data_objects(cmd, true); kfree(cmd); } } /* * Checks that the given cache block is either unmapped or clean. */ static int block_clean_combined_dirty(struct dm_cache_metadata *cmd, dm_cblock_t b, bool *result) { int r; __le64 value; dm_oblock_t ob; unsigned flags; r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(b), &value); if (r) return r; unpack_value(value, &ob, &flags); *result = !((flags & M_VALID) && (flags & M_DIRTY)); return 0; } static int blocks_are_clean_combined_dirty(struct dm_cache_metadata *cmd, dm_cblock_t begin, dm_cblock_t end, bool *result) { int r; *result = true; while (begin != end) { r = block_clean_combined_dirty(cmd, begin, result); if (r) { DMERR("block_clean_combined_dirty failed"); return r; } if (!*result) { DMERR("cache block %llu is dirty", (unsigned long long) from_cblock(begin)); return 0; } begin = to_cblock(from_cblock(begin) + 1); } return 0; } static int blocks_are_clean_separate_dirty(struct dm_cache_metadata *cmd, dm_cblock_t begin, dm_cblock_t end, bool *result) { int r; bool dirty_flag; *result = true; if (from_cblock(cmd->cache_blocks) == 0) /* Nothing to do */ return 0; r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root, from_cblock(cmd->cache_blocks), &cmd->dirty_cursor); if (r) { DMERR("%s: dm_bitset_cursor_begin for dirty failed", __func__); return r; } r = dm_bitset_cursor_skip(&cmd->dirty_cursor, from_cblock(begin)); if (r) { DMERR("%s: dm_bitset_cursor_skip for dirty failed", __func__); dm_bitset_cursor_end(&cmd->dirty_cursor); return r; } while (begin != end) { /* * We assume that unmapped blocks have their dirty bit * cleared. */ dirty_flag = dm_bitset_cursor_get_value(&cmd->dirty_cursor); if (dirty_flag) { DMERR("%s: cache block %llu is dirty", __func__, (unsigned long long) from_cblock(begin)); dm_bitset_cursor_end(&cmd->dirty_cursor); *result = false; return 0; } begin = to_cblock(from_cblock(begin) + 1); if (begin == end) break; r = dm_bitset_cursor_next(&cmd->dirty_cursor); if (r) { DMERR("%s: dm_bitset_cursor_next for dirty failed", __func__); dm_bitset_cursor_end(&cmd->dirty_cursor); return r; } } dm_bitset_cursor_end(&cmd->dirty_cursor); return 0; } static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd, dm_cblock_t begin, dm_cblock_t end, bool *result) { if (separate_dirty_bits(cmd)) return blocks_are_clean_separate_dirty(cmd, begin, end, result); else return blocks_are_clean_combined_dirty(cmd, begin, end, result); } static bool cmd_write_lock(struct dm_cache_metadata *cmd) { down_write(&cmd->root_lock); if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) { up_write(&cmd->root_lock); return false; } return true; } #define WRITE_LOCK(cmd) \ do { \ if (!cmd_write_lock((cmd))) \ return -EINVAL; \ } while(0) #define WRITE_LOCK_VOID(cmd) \ do { \ if (!cmd_write_lock((cmd))) \ return; \ } while(0) #define WRITE_UNLOCK(cmd) \ up_write(&(cmd)->root_lock) static bool cmd_read_lock(struct dm_cache_metadata *cmd) { down_read(&cmd->root_lock); if (cmd->fail_io) { up_read(&cmd->root_lock); return false; } return true; } #define READ_LOCK(cmd) \ do { \ if (!cmd_read_lock((cmd))) \ return -EINVAL; \ } while(0) #define READ_LOCK_VOID(cmd) \ do { \ if (!cmd_read_lock((cmd))) \ return; \ } while(0) #define READ_UNLOCK(cmd) \ up_read(&(cmd)->root_lock) int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size) { int r; bool clean; __le64 null_mapping = pack_value(0, 0); WRITE_LOCK(cmd); __dm_bless_for_disk(&null_mapping); if (from_cblock(new_cache_size) < from_cblock(cmd->cache_blocks)) { r = blocks_are_unmapped_or_clean(cmd, new_cache_size, cmd->cache_blocks, &clean); if (r) { __dm_unbless_for_disk(&null_mapping); goto out; } if (!clean) { DMERR("unable to shrink cache due to dirty blocks"); r = -EINVAL; __dm_unbless_for_disk(&null_mapping); goto out; } } r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks), from_cblock(new_cache_size), &null_mapping, &cmd->root); if (r) goto out; if (separate_dirty_bits(cmd)) { r = dm_bitset_resize(&cmd->dirty_info, cmd->dirty_root, from_cblock(cmd->cache_blocks), from_cblock(new_cache_size), false, &cmd->dirty_root); if (r) goto out; } cmd->cache_blocks = new_cache_size; cmd->changed = true; out: WRITE_UNLOCK(cmd); return r; } int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd, sector_t discard_block_size, dm_dblock_t new_nr_entries) { int r; WRITE_LOCK(cmd); r = dm_bitset_resize(&cmd->discard_info, cmd->discard_root, from_dblock(cmd->discard_nr_blocks), from_dblock(new_nr_entries), false, &cmd->discard_root); if (!r) { cmd->discard_block_size = discard_block_size; cmd->discard_nr_blocks = new_nr_entries; } cmd->changed = true; WRITE_UNLOCK(cmd); return r; } static int __set_discard(struct dm_cache_metadata *cmd, dm_dblock_t b) { return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root, from_dblock(b), &cmd->discard_root); } static int __clear_discard(struct dm_cache_metadata *cmd, dm_dblock_t b) { return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root, from_dblock(b), &cmd->discard_root); } static int __discard(struct dm_cache_metadata *cmd, dm_dblock_t dblock, bool discard) { int r; r = (discard ? __set_discard : __clear_discard)(cmd, dblock); if (r) return r; cmd->changed = true; return 0; } int dm_cache_set_discard(struct dm_cache_metadata *cmd, dm_dblock_t dblock, bool discard) { int r; WRITE_LOCK(cmd); r = __discard(cmd, dblock, discard); WRITE_UNLOCK(cmd); return r; } static int __load_discards(struct dm_cache_metadata *cmd, load_discard_fn fn, void *context) { int r = 0; uint32_t b; struct dm_bitset_cursor c; if (from_dblock(cmd->discard_nr_blocks) == 0) /* nothing to do */ return 0; if (cmd->clean_when_opened) { r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root, &cmd->discard_root); if (r) return r; r = dm_bitset_cursor_begin(&cmd->discard_info, cmd->discard_root, from_dblock(cmd->discard_nr_blocks), &c); if (r) return r; for (b = 0; ; b++) { r = fn(context, cmd->discard_block_size, to_dblock(b), dm_bitset_cursor_get_value(&c)); if (r) break; if (b >= (from_dblock(cmd->discard_nr_blocks) - 1)) break; r = dm_bitset_cursor_next(&c); if (r) break; } dm_bitset_cursor_end(&c); } else { for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) { r = fn(context, cmd->discard_block_size, to_dblock(b), false); if (r) return r; } } return r; } int dm_cache_load_discards(struct dm_cache_metadata *cmd, load_discard_fn fn, void *context) { int r; READ_LOCK(cmd); r = __load_discards(cmd, fn, context); READ_UNLOCK(cmd); return r; } int dm_cache_size(struct dm_cache_metadata *cmd, dm_cblock_t *result) { READ_LOCK(cmd); *result = cmd->cache_blocks; READ_UNLOCK(cmd); return 0; } static int __remove(struct dm_cache_metadata *cmd, dm_cblock_t cblock) { int r; __le64 value = pack_value(0, 0); __dm_bless_for_disk(&value); r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock), &value, &cmd->root); if (r) return r; cmd->changed = true; return 0; } int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock) { int r; WRITE_LOCK(cmd); r = __remove(cmd, cblock); WRITE_UNLOCK(cmd); return r; } static int __insert(struct dm_cache_metadata *cmd, dm_cblock_t cblock, dm_oblock_t oblock) { int r; __le64 value = pack_value(oblock, M_VALID); __dm_bless_for_disk(&value); r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock), &value, &cmd->root); if (r) return r; cmd->changed = true; return 0; } int dm_cache_insert_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock, dm_oblock_t oblock) { int r; WRITE_LOCK(cmd); r = __insert(cmd, cblock, oblock); WRITE_UNLOCK(cmd); return r; } struct thunk { load_mapping_fn fn; void *context; struct dm_cache_metadata *cmd; bool respect_dirty_flags; bool hints_valid; }; static bool policy_unchanged(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy) { const char *policy_name = dm_cache_policy_get_name(policy); const unsigned *policy_version = dm_cache_policy_get_version(policy); size_t policy_hint_size = dm_cache_policy_get_hint_size(policy); /* * Ensure policy names match. */ if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name))) return false; /* * Ensure policy major versions match. */ if (cmd->policy_version[0] != policy_version[0]) return false; /* * Ensure policy hint sizes match. */ if (cmd->policy_hint_size != policy_hint_size) return false; return true; } static bool hints_array_initialized(struct dm_cache_metadata *cmd) { return cmd->hint_root && cmd->policy_hint_size; } static bool hints_array_available(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy) { return cmd->clean_when_opened && policy_unchanged(cmd, policy) && hints_array_initialized(cmd); } static int __load_mapping_v1(struct dm_cache_metadata *cmd, uint64_t cb, bool hints_valid, struct dm_array_cursor *mapping_cursor, struct dm_array_cursor *hint_cursor, load_mapping_fn fn, void *context) { int r = 0; __le64 mapping; __le32 hint = 0; __le64 *mapping_value_le; __le32 *hint_value_le; dm_oblock_t oblock; unsigned flags; bool dirty = true; dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le); memcpy(&mapping, mapping_value_le, sizeof(mapping)); unpack_value(mapping, &oblock, &flags); if (flags & M_VALID) { if (hints_valid) { dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le); memcpy(&hint, hint_value_le, sizeof(hint)); } if (cmd->clean_when_opened) dirty = flags & M_DIRTY; r = fn(context, oblock, to_cblock(cb), dirty, le32_to_cpu(hint), hints_valid); if (r) { DMERR("policy couldn't load cache block %llu", (unsigned long long) from_cblock(to_cblock(cb))); } } return r; } static int __load_mapping_v2(struct dm_cache_metadata *cmd, uint64_t cb, bool hints_valid, struct dm_array_cursor *mapping_cursor, struct dm_array_cursor *hint_cursor, struct dm_bitset_cursor *dirty_cursor, load_mapping_fn fn, void *context) { int r = 0; __le64 mapping; __le32 hint = 0; __le64 *mapping_value_le; __le32 *hint_value_le; dm_oblock_t oblock; unsigned flags; bool dirty = true; dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le); memcpy(&mapping, mapping_value_le, sizeof(mapping)); unpack_value(mapping, &oblock, &flags); if (flags & M_VALID) { if (hints_valid) { dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le); memcpy(&hint, hint_value_le, sizeof(hint)); } if (cmd->clean_when_opened) dirty = dm_bitset_cursor_get_value(dirty_cursor); r = fn(context, oblock, to_cblock(cb), dirty, le32_to_cpu(hint), hints_valid); if (r) { DMERR("policy couldn't load cache block %llu", (unsigned long long) from_cblock(to_cblock(cb))); } } return r; } static int __load_mappings(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy, load_mapping_fn fn, void *context) { int r; uint64_t cb; bool hints_valid = hints_array_available(cmd, policy); if (from_cblock(cmd->cache_blocks) == 0) /* Nothing to do */ return 0; r = dm_array_cursor_begin(&cmd->info, cmd->root, &cmd->mapping_cursor); if (r) return r; if (hints_valid) { r = dm_array_cursor_begin(&cmd->hint_info, cmd->hint_root, &cmd->hint_cursor); if (r) { dm_array_cursor_end(&cmd->mapping_cursor); return r; } } if (separate_dirty_bits(cmd)) { r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root, from_cblock(cmd->cache_blocks), &cmd->dirty_cursor); if (r) { dm_array_cursor_end(&cmd->hint_cursor); dm_array_cursor_end(&cmd->mapping_cursor); return r; } } for (cb = 0; ; cb++) { if (separate_dirty_bits(cmd)) r = __load_mapping_v2(cmd, cb, hints_valid, &cmd->mapping_cursor, &cmd->hint_cursor, &cmd->dirty_cursor, fn, context); else r = __load_mapping_v1(cmd, cb, hints_valid, &cmd->mapping_cursor, &cmd->hint_cursor, fn, context); if (r) goto out; /* * We need to break out before we move the cursors. */ if (cb >= (from_cblock(cmd->cache_blocks) - 1)) break; r = dm_array_cursor_next(&cmd->mapping_cursor); if (r) { DMERR("dm_array_cursor_next for mapping failed"); goto out; } if (hints_valid) { r = dm_array_cursor_next(&cmd->hint_cursor); if (r) { dm_array_cursor_end(&cmd->hint_cursor); hints_valid = false; } } if (separate_dirty_bits(cmd)) { r = dm_bitset_cursor_next(&cmd->dirty_cursor); if (r) { DMERR("dm_bitset_cursor_next for dirty failed"); goto out; } } } out: dm_array_cursor_end(&cmd->mapping_cursor); if (hints_valid) dm_array_cursor_end(&cmd->hint_cursor); if (separate_dirty_bits(cmd)) dm_bitset_cursor_end(&cmd->dirty_cursor); return r; } int dm_cache_load_mappings(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy, load_mapping_fn fn, void *context) { int r; READ_LOCK(cmd); r = __load_mappings(cmd, policy, fn, context); READ_UNLOCK(cmd); return r; } static int __dump_mapping(void *context, uint64_t cblock, void *leaf) { __le64 value; dm_oblock_t oblock; unsigned flags; memcpy(&value, leaf, sizeof(value)); unpack_value(value, &oblock, &flags); return 0; } static int __dump_mappings(struct dm_cache_metadata *cmd) { return dm_array_walk(&cmd->info, cmd->root, __dump_mapping, NULL); } void dm_cache_dump(struct dm_cache_metadata *cmd) { READ_LOCK_VOID(cmd); __dump_mappings(cmd); READ_UNLOCK(cmd); } int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd) { int r; READ_LOCK(cmd); r = cmd->changed; READ_UNLOCK(cmd); return r; } static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty) { int r; unsigned flags; dm_oblock_t oblock; __le64 value; r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(cblock), &value); if (r) return r; unpack_value(value, &oblock, &flags); if (((flags & M_DIRTY) && dirty) || (!(flags & M_DIRTY) && !dirty)) /* nothing to be done */ return 0; value = pack_value(oblock, (flags & ~M_DIRTY) | (dirty ? M_DIRTY : 0)); __dm_bless_for_disk(&value); r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock), &value, &cmd->root); if (r) return r; cmd->changed = true; return 0; } static int __set_dirty_bits_v1(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits) { int r; unsigned i; for (i = 0; i < nr_bits; i++) { r = __dirty(cmd, to_cblock(i), test_bit(i, bits)); if (r) return r; } return 0; } static int is_dirty_callback(uint32_t index, bool *value, void *context) { unsigned long *bits = context; *value = test_bit(index, bits); return 0; } static int __set_dirty_bits_v2(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits) { int r = 0; /* nr_bits is really just a sanity check */ if (nr_bits != from_cblock(cmd->cache_blocks)) { DMERR("dirty bitset is wrong size"); return -EINVAL; } r = dm_bitset_del(&cmd->dirty_info, cmd->dirty_root); if (r) return r; cmd->changed = true; return dm_bitset_new(&cmd->dirty_info, &cmd->dirty_root, nr_bits, is_dirty_callback, bits); } int dm_cache_set_dirty_bits(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits) { int r; WRITE_LOCK(cmd); if (separate_dirty_bits(cmd)) r = __set_dirty_bits_v2(cmd, nr_bits, bits); else r = __set_dirty_bits_v1(cmd, nr_bits, bits); WRITE_UNLOCK(cmd); return r; } void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd, struct dm_cache_statistics *stats) { READ_LOCK_VOID(cmd); *stats = cmd->stats; READ_UNLOCK(cmd); } void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd, struct dm_cache_statistics *stats) { WRITE_LOCK_VOID(cmd); cmd->stats = *stats; WRITE_UNLOCK(cmd); } int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown) { int r = -EINVAL; flags_mutator mutator = (clean_shutdown ? set_clean_shutdown : clear_clean_shutdown); WRITE_LOCK(cmd); if (cmd->fail_io) goto out; r = __commit_transaction(cmd, mutator); if (r) goto out; r = __begin_transaction(cmd); out: WRITE_UNLOCK(cmd); return r; } int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd, dm_block_t *result) { int r = -EINVAL; READ_LOCK(cmd); if (!cmd->fail_io) r = dm_sm_get_nr_free(cmd->metadata_sm, result); READ_UNLOCK(cmd); return r; } int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd, dm_block_t *result) { int r = -EINVAL; READ_LOCK(cmd); if (!cmd->fail_io) r = dm_sm_get_nr_blocks(cmd->metadata_sm, result); READ_UNLOCK(cmd); return r; } /*----------------------------------------------------------------*/ static int get_hint(uint32_t index, void *value_le, void *context) { uint32_t value; struct dm_cache_policy *policy = context; value = policy_get_hint(policy, to_cblock(index)); *((__le32 *) value_le) = cpu_to_le32(value); return 0; } /* * It's quicker to always delete the hint array, and recreate with * dm_array_new(). */ static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy) { int r; size_t hint_size; const char *policy_name = dm_cache_policy_get_name(policy); const unsigned *policy_version = dm_cache_policy_get_version(policy); if (!policy_name[0] || (strlen(policy_name) > sizeof(cmd->policy_name) - 1)) return -EINVAL; strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name)); memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version)); hint_size = dm_cache_policy_get_hint_size(policy); if (!hint_size) return 0; /* short-circuit hints initialization */ cmd->policy_hint_size = hint_size; if (cmd->hint_root) { r = dm_array_del(&cmd->hint_info, cmd->hint_root); if (r) return r; } return dm_array_new(&cmd->hint_info, &cmd->hint_root, from_cblock(cmd->cache_blocks), get_hint, policy); } int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy) { int r; WRITE_LOCK(cmd); r = write_hints(cmd, policy); WRITE_UNLOCK(cmd); return r; } int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result) { int r; READ_LOCK(cmd); r = blocks_are_unmapped_or_clean(cmd, 0, cmd->cache_blocks, result); READ_UNLOCK(cmd); return r; } void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd) { WRITE_LOCK_VOID(cmd); dm_bm_set_read_only(cmd->bm); WRITE_UNLOCK(cmd); } void dm_cache_metadata_set_read_write(struct dm_cache_metadata *cmd) { WRITE_LOCK_VOID(cmd); dm_bm_set_read_write(cmd->bm); WRITE_UNLOCK(cmd); } int dm_cache_metadata_set_needs_check(struct dm_cache_metadata *cmd) { int r; struct dm_block *sblock; struct cache_disk_superblock *disk_super; WRITE_LOCK(cmd); set_bit(NEEDS_CHECK, &cmd->flags); r = superblock_lock(cmd, &sblock); if (r) { DMERR("couldn't read superblock"); goto out; } disk_super = dm_block_data(sblock); disk_super->flags = cpu_to_le32(cmd->flags); dm_bm_unlock(sblock); out: WRITE_UNLOCK(cmd); return r; } int dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd, bool *result) { READ_LOCK(cmd); *result = !!test_bit(NEEDS_CHECK, &cmd->flags); READ_UNLOCK(cmd); return 0; } int dm_cache_metadata_abort(struct dm_cache_metadata *cmd) { int r = -EINVAL; struct dm_block_manager *old_bm = NULL, *new_bm = NULL; /* fail_io is double-checked with cmd->root_lock held below */ if (unlikely(cmd->fail_io)) return r; /* * Replacement block manager (new_bm) is created and old_bm destroyed outside of * cmd root_lock to avoid ABBA deadlock that would result (due to life-cycle of * shrinker associated with the block manager's bufio client vs cmd root_lock). * - must take shrinker_rwsem without holding cmd->root_lock */ new_bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT, CACHE_MAX_CONCURRENT_LOCKS); WRITE_LOCK(cmd); if (cmd->fail_io) { WRITE_UNLOCK(cmd); goto out; } __destroy_persistent_data_objects(cmd, false); old_bm = cmd->bm; if (IS_ERR(new_bm)) { DMERR("could not create block manager during abort"); cmd->bm = NULL; r = PTR_ERR(new_bm); goto out_unlock; } cmd->bm = new_bm; r = __open_or_format_metadata(cmd, false); if (r) { cmd->bm = NULL; goto out_unlock; } new_bm = NULL; out_unlock: if (r) cmd->fail_io = true; WRITE_UNLOCK(cmd); dm_block_manager_destroy(old_bm); out: if (new_bm && !IS_ERR(new_bm)) dm_block_manager_destroy(new_bm); return r; }
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