diff options
Diffstat (limited to 'drivers/md/dm-clone-metadata.h')
| -rw-r--r-- | drivers/md/dm-clone-metadata.h | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/drivers/md/dm-clone-metadata.h b/drivers/md/dm-clone-metadata.h index 3fe50a781c11..14af1ebd853f 100644 --- a/drivers/md/dm-clone-metadata.h +++ b/drivers/md/dm-clone-metadata.h @@ -75,7 +75,23 @@ void dm_clone_metadata_close(struct dm_clone_metadata *cmd); /* * Commit dm-clone metadata to disk. + * + * We use a two phase commit: + * + * 1. dm_clone_metadata_pre_commit(): Prepare the current transaction for + * committing. After this is called, all subsequent metadata updates, done + * through either dm_clone_set_region_hydrated() or + * dm_clone_cond_set_range(), will be part of the **next** transaction. + * + * 2. dm_clone_metadata_commit(): Actually commit the current transaction to + * disk and start a new transaction. + * + * This allows dm-clone to flush the destination device after step (1) to + * ensure that all freshly hydrated regions, for which we are updating the + * metadata, are properly written to non-volatile storage and won't be lost in + * case of a crash. */ +int dm_clone_metadata_pre_commit(struct dm_clone_metadata *cmd); int dm_clone_metadata_commit(struct dm_clone_metadata *cmd); /* @@ -112,6 +128,7 @@ int dm_clone_metadata_abort(struct dm_clone_metadata *cmd); * Switches metadata to a read only mode. Once read-only mode has been entered * the following functions will return -EPERM: * + * dm_clone_metadata_pre_commit() * dm_clone_metadata_commit() * dm_clone_set_region_hydrated() * dm_clone_cond_set_range() |