Sets num_flush_requests=2 to support flushing both the origin and cow
devices used by the snapshot-merge target.
Also, snapshot_ctr() now gets the origin device using FMODE_WRITE if the
target is snapshot-merge (which writes to the origin device).
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
NOTE: this patch is made to follow:
v5-05-13-dm-snapshot-merge-target-should-not-allocate-new-exceptions.patch
---
drivers/md/dm-snap.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
Index: linux-2.6/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-snap.c
+++ linux-2.6/drivers/md/dm-snap.c
@@ -704,7 +704,8 @@ static int snapshot_ctr(struct dm_target
int i;
int r = -EINVAL;
char *origin_path, *cow_path;
- unsigned args_used;
+ unsigned args_used, num_flush_requests = 1;
+ fmode_t origin_mode = FMODE_READ;
if (argc != 4) {
ti->error = "requires exactly 4 arguments";
@@ -712,6 +713,11 @@ static int snapshot_ctr(struct dm_target
goto bad;
}
+ if (dm_target_is_snapshot_merge(ti)) {
+ num_flush_requests = 2;
+ origin_mode = FMODE_WRITE;
+ }
+
origin_path = argv[0];
argv++;
argc--;
@@ -745,7 +751,7 @@ static int snapshot_ctr(struct dm_target
argv += args_used;
argc -= args_used;
- r = dm_get_device(ti, origin_path, 0, ti->len, FMODE_READ, &s->origin);
+ r = dm_get_device(ti, origin_path, 0, ti->len, origin_mode, &s->origin);
if (r) {
ti->error = "Cannot get origin device";
goto bad_origin;
@@ -796,7 +802,7 @@ static int snapshot_ctr(struct dm_target
INIT_WORK(&s->queued_bios_work, flush_queued_bios);
ti->private = s;
- ti->num_flush_requests = 1;
+ ti->num_flush_requests = num_flush_requests;
/* Add snapshot to the list of snapshots for this origin */
/* Exceptions aren't triggered till snapshot_resume() is called */
@@ -1322,6 +1328,14 @@ static int snapshot_merge_map(struct dm_
int r = DM_MAPIO_REMAPPED;
chunk_t chunk;
+ if (unlikely(bio_empty_barrier(bio))) {
+ if (map_context->flush_request == 0)
+ bio->bi_bdev = s->origin->bdev;
+ else if (map_context->flush_request == 1)
+ bio->bi_bdev = s->cow->bdev;
+ return DM_MAPIO_REMAPPED;
+ }
+
chunk = sector_to_chunk(s->store, bio->bi_sector);
down_read(&s->lock);
--
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