Comments
Patch
===================================================================
@@ -1268,16 +1268,27 @@ static void snapshot_resume(struct dm_ta
struct dm_snapshot *s = ti->private;
down_write(&s->lock);
- if (s->handover) {
- /* Get exception store from another snapshot */
+ if (s->handover_snap) {
+ /*
+ * Initially assumes this snapshot will get
+ * exception store from another snapshot
+ */
struct dm_snapshot *old_snap = s->handover_snap;
- BUG_ON(!old_snap);
- down_write_nested(&old_snap->lock, SINGLE_DEPTH_NESTING);
- handover_exceptions(old_snap, s);
- up_write(&old_snap->lock);
+ struct dm_snapshot *new_snap = s;
+ struct dm_snapshot *lock_snap = old_snap;
+ if (!s->handover) {
+ /* Handover exceptions to another snapshot */
+ old_snap = s;
+ new_snap = s->handover_snap;
+ lock_snap = new_snap;
+ }
+ down_write_nested(&lock_snap->lock,
+ SINGLE_DEPTH_NESTING);
+ handover_exceptions(old_snap, new_snap);
+ up_write(&lock_snap->lock);
}
/* An incomplete exception handover is not allowed */
- BUG_ON(s->handover || s->handover_snap);
+ BUG_ON(s->handover_snap);
s->active = 1;
s->suspended = 0;
up_write(&s->lock);
Until now snapshot_resume only allowed the resuming snapshot to get the exception store from another snapshot. Revise snapshot_resume's exception handover to allow a snapshot to handover its exceptions to another snapshot prior to resuming. This is needed to accomodate the following sequence: new_snapshot->ctr old_snapshot->suspend old_snapshot->resume new_snapshot->resume lvm2 relies on this sequence if 'lvchange --refresh' is used to start a snapshot merge that was deferred until both origin and snapshot were not in use. Signed-off-by: Mike Snitzer <snitzer@redhat.com> --- drivers/md/dm-snap.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel