diff options
Diffstat (limited to 'drivers/md/dm-thin-metadata.h')
| -rw-r--r-- | drivers/md/dm-thin-metadata.h | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/drivers/md/dm-thin-metadata.h b/drivers/md/dm-thin-metadata.h index ed4725e67c9..b88918ccdaf 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. |