diff options
| -rw-r--r-- | Documentation/device-mapper/cache.txt | 11 | ||||
| -rw-r--r-- | Documentation/device-mapper/thin-provisioning.txt | 29 | ||||
| -rw-r--r-- | drivers/md/dm-thin-metadata.c | 37 | ||||
| -rw-r--r-- | drivers/md/dm-thin-metadata.h | 11 | ||||
| -rw-r--r-- | drivers/md/dm-thin.c | 76 |
5 files changed, 135 insertions, 29 deletions
diff --git a/Documentation/device-mapper/cache.txt b/Documentation/device-mapper/cache.txt index e6b72d3..68c0f51 100644 --- a/Documentation/device-mapper/cache.txt +++ b/Documentation/device-mapper/cache.txt @@ -124,12 +124,11 @@ the default being 204800 sectors (or 100MB). Updating on-disk metadata ------------------------- -On-disk metadata is committed every time a REQ_SYNC or REQ_FUA bio is -written. If no such requests are made then commits will occur every -second. This means the cache behaves like a physical disk that has a -write cache (the same is true of the thin-provisioning target). If -power is lost you may lose some recent writes. The metadata should -always be consistent in spite of any crash. +On-disk metadata is committed every time a FLUSH or FUA bio is written. +If no such requests are made then commits will occur every second. This +means the cache behaves like a physical disk that has a volatile write +cache. If power is lost you may lose some recent writes. The metadata +should always be consistent in spite of any crash. The 'dirty' state for a cache block changes far too frequently for us to keep updating it on the fly. So we treat it as a hint. In normal diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentation/device-mapper/thin-provisioning.txt index 8a7a3d4..3b34b4f 100644 --- a/Documentation/device-mapper/thin-provisioning.txt +++ b/Documentation/device-mapper/thin-provisioning.txt @@ -116,6 +116,35 @@ Resuming a device with a new table itself triggers an event so the userspace daemon can use this to detect a situation where a new table already exceeds the threshold. +A low water mark for the metadata device is maintained in the kernel and +will trigger a dm event if free space on the metadata device drops below +it. + +Updating on-disk metadata +------------------------- + +On-disk metadata is committed every time a FLUSH or FUA bio is written. +If no such requests are made then commits will occur every second. This +means the thin-provisioning target behaves like a physical disk that has +a volatile write cache. If power is lost you may lose some recent +writes. The metadata should always be consistent in spite of any crash. + +If data space is exhausted the pool will either error or queue IO +according to the configuration (see: error_if_no_space). If metadata +space is exhausted or a metadata operation fails: the pool will error IO +until the pool is taken offline and repair is performed to 1) fix any +potential inconsistencies and 2) clear the flag that imposes repair. +Once the pool's metadata device is repaired it may be resized, which +will allow the pool to return to normal operation. Note that if a pool +is flagged as needing repair, the pool's data and metadata devices +cannot be resized until repair is performed. It should also be noted +that when the pool's metadata space is exhausted the current metadata +transaction is aborted. Given that the pool will cache IO whose +completion may have already been acknowledged to upper IO layers +(e.g. filesystem) it is strongly suggested that consistency checks +(e.g. fsck) be performed on those layers when repair of the pool is +required. + Thin provisioning ----------------- diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c index baa87ff..fb9efc8 100644 --- a/drivers/md/dm-thin-metadata.c +++ b/drivers/md/dm-thin-metadata.c @@ -76,7 +76,7 @@ #define THIN_SUPERBLOCK_MAGIC 27022010 #define THIN_SUPERBLOCK_LOCATION 0 -#define THIN_VERSION 1 +#define THIN_VERSION 2 #define THIN_METADATA_CACHE_SIZE 64 #define SECTOR_TO_BLOCK_SHIFT 3 @@ -1755,3 +1755,38 @@ int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd, return r; } + +int dm_pool_metadata_set_needs_check(struct dm_pool_metadata *pmd) +{ + int r; + struct dm_block *sblock; + struct thin_disk_superblock *disk_super; + + down_write(&pmd->root_lock); + pmd->flags |= THIN_METADATA_NEEDS_CHECK_FLAG; + + r = superblock_lock(pmd, &sblock); + if (r) { + DMERR("couldn't read superblock"); + goto out; + } + + disk_super = dm_block_data(sblock); + disk_super->flags = cpu_to_le32(pmd->flags); + + dm_bm_unlock(sblock); +out: + up_write(&pmd->root_lock); + return r; +} + +bool dm_pool_metadata_needs_check(struct dm_pool_metadata *pmd) +{ + bool needs_check; + + down_read(&pmd->root_lock); + needs_check = pmd->flags & THIN_METADATA_NEEDS_CHECK_FLAG; + up_read(&pmd->root_lock); + + return needs_check; +} diff --git a/drivers/md/dm-thin-metadata.h b/drivers/md/dm-thin-metadata.h index 82ea384..e3c857d 100644 --- a/drivers/md/dm-thin-metadata.h +++ b/drivers/md/dm-thin-metadata.h @@ -25,6 +25,11 @@ /*----------------------------------------------------------------*/ +/* + * Thin metadata superblock flags. + */ +#define THIN_METADATA_NEEDS_CHECK_FLAG (1 << 0) + struct dm_pool_metadata; struct dm_thin_device; @@ -202,6 +207,12 @@ int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd, dm_sm_threshold_fn fn, void *context); +/* + * Updates the superblock immediately. + */ +int dm_pool_metadata_set_needs_check(struct dm_pool_metadata *pmd); +bool dm_pool_metadata_needs_check(struct dm_pool_metadata *pmd); + /*----------------------------------------------------------------*/ #endif diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index dfa48ec..a04eba9 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -1403,7 +1403,28 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode) { int r; struct pool_c *pt = pool->ti->private; - enum pool_mode old_mode = pool->pf.mode; + bool needs_check = dm_pool_metadata_needs_check(pool->pmd); + enum pool_mode old_mode = get_pool_mode(pool); + + /* + * Never allow the pool to transition to PM_WRITE mode if user + * intervention is required to verify metadata and data consistency. + */ + if (new_mode == PM_WRITE && needs_check) { + DMERR("%s: unable to switch pool to write mode until repaired.", + dm_device_name(pool->pool_md)); + if (old_mode != new_mode) + new_mode = old_mode; + else + new_mode = PM_READ_ONLY; + } + /* + * If we were in PM_FAIL mode, rollback of metadata failed. We're + * not going to recover without a thin_repair. So we never let the + * pool move out of the old mode. + */ + if (old_mode == PM_FAIL) + new_mode = old_mode; switch (new_mode) { case PM_FAIL: @@ -1467,19 +1488,28 @@ static void out_of_data_space(struct pool *pool) set_pool_mode(pool, PM_READ_ONLY); } -static void metadata_operation_failed(struct pool *pool, const char *op, int r) +static void abort_transaction(struct pool *pool) { - dm_block_t free_blocks; + const char *dev_name = dm_device_name(pool->pool_md); + + DMERR_LIMIT("%s: aborting current metadata transaction", dev_name); + if (dm_pool_abort_metadata(pool->pmd)) { + DMERR("%s: failed to abort metadata transaction", dev_name); + set_pool_mode(pool, PM_FAIL); + } + + if (dm_pool_metadata_set_needs_check(pool->pmd)) { + DMERR("%s: failed to set 'needs_check' flag in metadata", dev_name); + set_pool_mode(pool, PM_FAIL); + } +} +static void metadata_operation_failed(struct pool *pool, const char *op, int r) +{ DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d", dm_device_name(pool->pool_md), op, r); - if (r == -ENOSPC && - !dm_pool_get_free_metadata_block_count(pool->pmd, &free_blocks) && - !free_blocks) - DMERR_LIMIT("%s: no free metadata space available.", - dm_device_name(pool->pool_md)); - + abort_transaction(pool); set_pool_mode(pool, PM_READ_ONLY); } @@ -1693,7 +1723,7 @@ static int bind_control_target(struct pool *pool, struct dm_target *ti) /* * We want to make sure that a pool in PM_FAIL mode is never upgraded. */ - enum pool_mode old_mode = pool->pf.mode; + enum pool_mode old_mode = get_pool_mode(pool); enum pool_mode new_mode = pt->adjusted_pf.mode; /* @@ -1707,16 +1737,6 @@ static int bind_control_target(struct pool *pool, struct dm_target *ti) pool->pf = pt->adjusted_pf; pool->low_water_blocks = pt->low_water_blocks; - /* - * If we were in PM_FAIL mode, rollback of metadata failed. We're - * not going to recover without a thin_repair. So we never let the - * pool move out of the old mode. On the other hand a PM_READ_ONLY - * may have been due to a lack of metadata or data space, and may - * now work (ie. if the underlying devices have been resized). - */ - if (old_mode == PM_FAIL) - new_mode = old_mode; - set_pool_mode(pool, new_mode); return 0; @@ -2259,6 +2279,12 @@ static int maybe_resize_data_dev(struct dm_target *ti, bool *need_commit) return -EINVAL; } else if (data_size > sb_data_size) { + if (dm_pool_metadata_needs_check(pool->pmd)) { + DMERR("%s: unable to grow the data device until repaired.", + dm_device_name(pool->pool_md)); + return 0; + } + if (sb_data_size) DMINFO("%s: growing the data device from %llu to %llu blocks", dm_device_name(pool->pool_md), @@ -2300,6 +2326,12 @@ static int maybe_resize_metadata_dev(struct dm_target *ti, bool *need_commit) return -EINVAL; } else if (metadata_dev_size > sb_metadata_dev_size) { + if (dm_pool_metadata_needs_check(pool->pmd)) { + DMERR("%s: unable to grow the metadata device until repaired.", + dm_device_name(pool->pool_md)); + return 0; + } + warn_if_metadata_device_too_big(pool->md_dev); DMINFO("%s: growing the metadata device from %llu to %llu blocks", dm_device_name(pool->pool_md), @@ -2801,7 +2833,7 @@ static struct target_type pool_target = { .name = "thin-pool", .features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE | DM_TARGET_IMMUTABLE, - .version = {1, 10, 0}, + .version = {1, 11, 0}, .module = THIS_MODULE, .ctr = pool_ctr, .dtr = pool_dtr, @@ -3091,7 +3123,7 @@ static int thin_iterate_devices(struct dm_target *ti, static struct target_type thin_target = { .name = "thin", - .version = {1, 10, 0}, + .version = {1, 11, 0}, .module = THIS_MODULE, .ctr = thin_ctr, .dtr = thin_dtr, |
