The snapshot-merge target allows a snapshot to be merged back into the snapshot's origin device. One expected use of snapshot merging is the rollback of a root filesystem after system upgrades (e.g.: yum update). snapshot-merge enables "system rollback" support for any filesystem that is using the associated DM/LVM devices. For LVM2 support please see: http://people.redhat.com/msnitzer/patches/snapshot-merge/lvm2/LVM2-2.02.57/ v5 of this snapshot-merge series has the following changes: * Updated to stack on agk's latest 'editing' quilt tree * Added more content to Documentation/device-mapper/snapshot.txt * Added comment block above snapshot_merge_map() * Improved DMERR messages in merge_callback() * Changed is_merge() macro to compare ti->type->name with a static string constant rather than checking ->map * 'merging' flag is no longer cleared in persistent_prepare_exception * Initialized 'merging_snap' to NULL in __find_merging_snapshot * Removed one level of nesting in __validate_exception_handover * Added 'merge_failed' flag to dm_snapshot structure and report merge failure accordingly in snapshot_status() Mike Snitzer (3): dm exception store: snapshot-merge usage accounting dm snapshot: merge a linear region of chunks using one large IO dm snapshot: report merge failure in status Mikulas Patocka (10): dm snapshot: rework writing to snapshot origin dm exception store: add snapshot-merge specific methods dm snapshot: add snapshot-merge target dm snapshot: merge target should not allocate new exceptions dm snapshot: do not allow more than one merging snapshot. dm snapshot: the merge procedure dm snapshot: queue writes to an area that is actively being merged dm snapshot: do not merge a chunk until active writes to it finish dm snapshot: make exceptions in other snapshots when merging dm snapshot: redirect accesses to origin if merging snap invalidated Documentation/device-mapper/snapshot.txt | 60 +++- drivers/md/dm-exception-store.h | 27 ++ drivers/md/dm-snap-persistent.c | 89 +++++- drivers/md/dm-snap.c | 603 +++++++++++++++++++++++------- 4 files changed, 647 insertions(+), 132 deletions(-) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
