diff options
Diffstat (limited to 'drivers/md/dm-cache-metadata.c')
| -rw-r--r-- | drivers/md/dm-cache-metadata.c | 173 |
1 files changed, 144 insertions, 29 deletions
diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c index 1af7255..0bfd9c0 100644 --- a/drivers/md/dm-cache-metadata.c +++ b/drivers/md/dm-cache-metadata.c @@ -88,6 +88,9 @@ struct cache_disk_superblock { } __packed; struct dm_cache_metadata { + atomic_t ref_count; + struct list_head list; + struct block_device *bdev; struct dm_block_manager *bm; struct dm_space_map *metadata_sm; @@ -114,6 +117,12 @@ struct dm_cache_metadata { 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]; }; /*------------------------------------------------------------------- @@ -242,11 +251,31 @@ static void __setup_mapping_info(struct dm_cache_metadata *cmd) } } +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 int __write_initial_superblock(struct dm_cache_metadata *cmd) { int r; struct dm_block *sblock; - size_t metadata_len; struct cache_disk_superblock *disk_super; sector_t bdev_size = i_size_read(cmd->bdev->bd_inode) >> SECTOR_SHIFT; @@ -254,12 +283,16 @@ static int __write_initial_superblock(struct dm_cache_metadata *cmd) if (bdev_size > DM_CACHE_METADATA_MAX_SECTORS) bdev_size = DM_CACHE_METADATA_MAX_SECTORS; - r = dm_sm_root_size(cmd->metadata_sm, &metadata_len); + r = dm_tm_pre_commit(cmd->tm); if (r < 0) return r; - r = dm_tm_pre_commit(cmd->tm); - if (r < 0) + /* + * 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); @@ -275,10 +308,7 @@ static int __write_initial_superblock(struct dm_cache_metadata *cmd) memset(disk_super->policy_version, 0, sizeof(disk_super->policy_version)); disk_super->policy_hint_size = 0; - r = dm_sm_copy_root(cmd->metadata_sm, &disk_super->metadata_space_map_root, - metadata_len); - if (r < 0) - goto bad_locked; + __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); @@ -295,10 +325,6 @@ static int __write_initial_superblock(struct dm_cache_metadata *cmd) disk_super->write_misses = cpu_to_le32(0); return dm_tm_commit(cmd->tm, sblock); - -bad_locked: - dm_bm_unlock(sblock); - return r; } static int __format_metadata(struct dm_cache_metadata *cmd) @@ -384,6 +410,15 @@ static int __open_metadata(struct dm_cache_metadata *cmd) 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; @@ -511,8 +546,9 @@ static int __begin_transaction_flags(struct dm_cache_metadata *cmd, 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_and_unlock(cmd->bm, sblock); + return dm_bm_flush(cmd->bm); } static int __begin_transaction(struct dm_cache_metadata *cmd) @@ -540,7 +576,6 @@ static int __commit_transaction(struct dm_cache_metadata *cmd, flags_mutator mutator) { int r; - size_t metadata_len; struct cache_disk_superblock *disk_super; struct dm_block *sblock; @@ -558,8 +593,8 @@ static int __commit_transaction(struct dm_cache_metadata *cmd, if (r < 0) return r; - r = dm_sm_root_size(cmd->metadata_sm, &metadata_len); - if (r < 0) + r = __save_sm_root(cmd); + if (r) return r; r = superblock_lock(cmd, &sblock); @@ -586,13 +621,7 @@ static int __commit_transaction(struct dm_cache_metadata *cmd, 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); - - r = dm_sm_copy_root(cmd->metadata_sm, &disk_super->metadata_space_map_root, - metadata_len); - if (r < 0) { - dm_bm_unlock(sblock); - return r; - } + __copy_sm_root(cmd, disk_super); return dm_tm_commit(cmd->tm, sblock); } @@ -624,10 +653,10 @@ static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags) /*----------------------------------------------------------------*/ -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) +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) { int r; struct dm_cache_metadata *cmd; @@ -638,6 +667,7 @@ struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev, return NULL; } + atomic_set(&cmd->ref_count, 1); init_rwsem(&cmd->root_lock); cmd->bdev = bdev; cmd->data_block_size = data_block_size; @@ -660,10 +690,95 @@ struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev, 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) { + atomic_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) +{ + 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); + if (cmd) { + mutex_lock(&table_lock); + cmd2 = lookup(bdev); + if (cmd2) { + mutex_unlock(&table_lock); + __destroy_persistent_data_objects(cmd); + 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)\n", + (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) +{ + struct dm_cache_metadata *cmd = lookup_or_open(bdev, data_block_size, + may_format_device, policy_hint_size); + if (cmd && !same_params(cmd, data_block_size)) { + dm_cache_metadata_close(cmd); + return NULL; + } + + return cmd; +} + void dm_cache_metadata_close(struct dm_cache_metadata *cmd) { - __destroy_persistent_data_objects(cmd); - kfree(cmd); + if (atomic_dec_and_test(&cmd->ref_count)) { + mutex_lock(&table_lock); + list_del(&cmd->list); + mutex_unlock(&table_lock); + + __destroy_persistent_data_objects(cmd); + kfree(cmd); + } } int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size) |