diff options
| -rw-r--r-- | Documentation/device-mapper/thin-provisioning.txt | 11 | ||||
| -rw-r--r-- | drivers/md/dm-thin-metadata.c | 136 | ||||
| -rw-r--r-- | drivers/md/dm-thin-metadata.h | 13 | ||||
| -rw-r--r-- | drivers/md/dm-thin.c | 42 | ||||
| -rw-r--r-- | drivers/md/persistent-data/dm-transaction-manager.c | 2 |
5 files changed, 193 insertions, 11 deletions
diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentation/device-mapper/thin-provisioning.txt index 3370bc4d7b98..f5cfc62b7ad3 100644 --- a/Documentation/device-mapper/thin-provisioning.txt +++ b/Documentation/device-mapper/thin-provisioning.txt @@ -287,6 +287,17 @@ iii) Messages the current transaction id is when you change it with this compare-and-swap message. + reserve_metadata_snap + + Reserve a copy of the data mapping btree for use by userland. + This allows userland to inspect the mappings as they were when + this message was executed. Use the pool's status command to + get the root block associated with the metadata snapshot. + + release_metadata_snap + + Release a previously reserved copy of the data mapping btree. + 'thin' target ------------- diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c index 737d38865b69..3e2907f0bc46 100644 --- a/drivers/md/dm-thin-metadata.c +++ b/drivers/md/dm-thin-metadata.c @@ -1082,12 +1082,89 @@ int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd, return 0; } -static int __get_held_metadata_root(struct dm_pool_metadata *pmd, - dm_block_t *result) +static int __reserve_metadata_snap(struct dm_pool_metadata *pmd) +{ + int r, inc; + struct thin_disk_superblock *disk_super; + struct dm_block *copy, *sblock; + dm_block_t held_root; + + /* + * Copy the superblock. + */ + dm_sm_inc_block(pmd->metadata_sm, THIN_SUPERBLOCK_LOCATION); + r = dm_tm_shadow_block(pmd->tm, THIN_SUPERBLOCK_LOCATION, + &sb_validator, ©, &inc); + if (r) + return r; + + BUG_ON(!inc); + + held_root = dm_block_location(copy); + disk_super = dm_block_data(copy); + + if (le64_to_cpu(disk_super->held_root)) { + DMWARN("Pool metadata snapshot already exists: release this before taking another."); + + dm_tm_dec(pmd->tm, held_root); + dm_tm_unlock(pmd->tm, copy); + pmd->need_commit = 1; + + return -EBUSY; + } + + /* + * Wipe the spacemap since we're not publishing this. + */ + memset(&disk_super->data_space_map_root, 0, + sizeof(disk_super->data_space_map_root)); + memset(&disk_super->metadata_space_map_root, 0, + sizeof(disk_super->metadata_space_map_root)); + + /* + * Increment the data structures that need to be preserved. + */ + dm_tm_inc(pmd->tm, le64_to_cpu(disk_super->data_mapping_root)); + dm_tm_inc(pmd->tm, le64_to_cpu(disk_super->device_details_root)); + dm_tm_unlock(pmd->tm, copy); + + /* + * Write the held root into the superblock. + */ + r = dm_bm_write_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION, + &sb_validator, &sblock); + if (r) { + dm_tm_dec(pmd->tm, held_root); + pmd->need_commit = 1; + return r; + } + + disk_super = dm_block_data(sblock); + disk_super->held_root = cpu_to_le64(held_root); + dm_bm_unlock(sblock); + + pmd->need_commit = 1; + + return 0; +} + +int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd) +{ + int r; + + down_write(&pmd->root_lock); + r = __reserve_metadata_snap(pmd); + up_write(&pmd->root_lock); + + return r; +} + +static int __release_metadata_snap(struct dm_pool_metadata *pmd) { int r; struct thin_disk_superblock *disk_super; - struct dm_block *sblock; + struct dm_block *sblock, *copy; + dm_block_t held_root; r = dm_bm_write_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION, &sb_validator, &sblock); @@ -1095,18 +1172,65 @@ static int __get_held_metadata_root(struct dm_pool_metadata *pmd, return r; disk_super = dm_block_data(sblock); + held_root = le64_to_cpu(disk_super->held_root); + disk_super->held_root = cpu_to_le64(0); + pmd->need_commit = 1; + + dm_bm_unlock(sblock); + + if (!held_root) { + DMWARN("No pool metadata snapshot found: nothing to release."); + return -EINVAL; + } + + r = dm_tm_read_lock(pmd->tm, held_root, &sb_validator, ©); + if (r) + return r; + + disk_super = dm_block_data(copy); + dm_sm_dec_block(pmd->metadata_sm, le64_to_cpu(disk_super->data_mapping_root)); + dm_sm_dec_block(pmd->metadata_sm, le64_to_cpu(disk_super->device_details_root)); + dm_sm_dec_block(pmd->metadata_sm, held_root); + + return dm_tm_unlock(pmd->tm, copy); +} + +int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd) +{ + int r; + + down_write(&pmd->root_lock); + r = __release_metadata_snap(pmd); + up_write(&pmd->root_lock); + + return r; +} + +static int __get_metadata_snap(struct dm_pool_metadata *pmd, + dm_block_t *result) +{ + int r; + struct thin_disk_superblock *disk_super; + struct dm_block *sblock; + + r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION, + &sb_validator, &sblock); + if (r) + return r; + + disk_super = dm_block_data(sblock); *result = le64_to_cpu(disk_super->held_root); return dm_bm_unlock(sblock); } -int dm_pool_get_held_metadata_root(struct dm_pool_metadata *pmd, - dm_block_t *result) +int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd, + dm_block_t *result) { int r; down_read(&pmd->root_lock); - r = __get_held_metadata_root(pmd, result); + r = __get_metadata_snap(pmd, result); up_read(&pmd->root_lock); return r; diff --git a/drivers/md/dm-thin-metadata.h b/drivers/md/dm-thin-metadata.h index ed4725e67c96..b88918ccdaf6 100644 --- a/drivers/md/dm-thin-metadata.h +++ b/drivers/md/dm-thin-metadata.h @@ -90,11 +90,18 @@ int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd, /* * Hold/get root for userspace transaction. + * + * The metadata snapshot is a copy of the current superblock (minus the + * space maps). Userland can access the data structures for READ + * operations only. A small performance hit is incurred by providing this + * copy of the metadata to userland due to extra copy-on-write operations + * on the metadata nodes. Release this as soon as you finish with it. */ -int dm_pool_hold_metadata_root(struct dm_pool_metadata *pmd); +int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd); +int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd); -int dm_pool_get_held_metadata_root(struct dm_pool_metadata *pmd, - dm_block_t *result); +int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd, + dm_block_t *result); /* * Actions on a single virtual device. diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index db1b041ce975..37fdaf81bd1f 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -2284,6 +2284,36 @@ static int process_set_transaction_id_mesg(unsigned argc, char **argv, struct po return 0; } +static int process_reserve_metadata_snap_mesg(unsigned argc, char **argv, struct pool *pool) +{ + int r; + + r = check_arg_count(argc, 1); + if (r) + return r; + + r = dm_pool_reserve_metadata_snap(pool->pmd); + if (r) + DMWARN("reserve_metadata_snap message failed."); + + return r; +} + +static int process_release_metadata_snap_mesg(unsigned argc, char **argv, struct pool *pool) +{ + int r; + + r = check_arg_count(argc, 1); + if (r) + return r; + + r = dm_pool_release_metadata_snap(pool->pmd); + if (r) + DMWARN("release_metadata_snap message failed."); + + return r; +} + /* * Messages supported: * create_thin <dev_id> @@ -2291,6 +2321,8 @@ static int process_set_transaction_id_mesg(unsigned argc, char **argv, struct po * delete <dev_id> * trim <dev_id> <new_size_in_sectors> * set_transaction_id <current_trans_id> <new_trans_id> + * reserve_metadata_snap + * release_metadata_snap */ static int pool_message(struct dm_target *ti, unsigned argc, char **argv) { @@ -2310,6 +2342,12 @@ static int pool_message(struct dm_target *ti, unsigned argc, char **argv) else if (!strcasecmp(argv[0], "set_transaction_id")) r = process_set_transaction_id_mesg(argc, argv, pool); + else if (!strcasecmp(argv[0], "reserve_metadata_snap")) + r = process_reserve_metadata_snap_mesg(argc, argv, pool); + + else if (!strcasecmp(argv[0], "release_metadata_snap")) + r = process_release_metadata_snap_mesg(argc, argv, pool); + else DMWARN("Unrecognised thin pool target message received: %s", argv[0]); @@ -2369,7 +2407,7 @@ static int pool_status(struct dm_target *ti, status_type_t type, if (r) return r; - r = dm_pool_get_held_metadata_root(pool->pmd, &held_root); + r = dm_pool_get_metadata_snap(pool->pmd, &held_root); if (r) return r; @@ -2465,7 +2503,7 @@ static struct target_type pool_target = { .name = "thin-pool", .features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE | DM_TARGET_IMMUTABLE, - .version = {1, 1, 0}, + .version = {1, 2, 0}, .module = THIS_MODULE, .ctr = pool_ctr, .dtr = pool_dtr, diff --git a/drivers/md/persistent-data/dm-transaction-manager.c b/drivers/md/persistent-data/dm-transaction-manager.c index 6f8d38747d7f..400fe144c0cd 100644 --- a/drivers/md/persistent-data/dm-transaction-manager.c +++ b/drivers/md/persistent-data/dm-transaction-manager.c @@ -249,6 +249,7 @@ int dm_tm_shadow_block(struct dm_transaction_manager *tm, dm_block_t orig, return r; } +EXPORT_SYMBOL_GPL(dm_tm_shadow_block); int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b, struct dm_block_validator *v, @@ -259,6 +260,7 @@ int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b, return dm_bm_read_lock(tm->bm, b, v, blk); } +EXPORT_SYMBOL_GPL(dm_tm_read_lock); int dm_tm_unlock(struct dm_transaction_manager *tm, struct dm_block *b) { |