diff options
| author | Mikulas Patocka <mpatocka@redhat.com> | 2012-07-20 14:25:05 +0100 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2012-07-20 14:25:05 +0100 |
| commit | 650d2a06b4fe1cc1d218c20e256650f68bf0ca31 (patch) | |
| tree | 586e7da8f7bd3e895b52514bb4bd1ff1f1400181 | |
| parent | 751f188dd5ab95b3f2b5f2f467c38aae5a2877eb (diff) | |
dm thin: do not send discards to shared blocks
When process_discard receives a partial discard that doesn't cover a
full block, it sends this discard down to that block. Unfortunately, the
block can be shared and the discard would corrupt the other snapshots
sharing this block.
This patch detects block sharing and ends the discard with success when
sending it to the shared block.
The above change means that if the device supports discard it can't be
guaranteed that a discard request zeroes data. Therefore, we set
ti->discard_zeroes_data_unsupported.
Thin target discard support with this bug arrived in commit
104655fd4dcebd50068ef30253a001da72e3a081 (dm thin: support discards).
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
| -rw-r--r-- | drivers/md/dm-thin.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index ce59824fb41..68694da0d21 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -1245,7 +1245,10 @@ static void process_discard(struct thin_c *tc, struct bio *bio) cell_release_singleton(cell, bio); cell_release_singleton(cell2, bio); - remap_and_issue(tc, bio, lookup_result.block); + if ((!lookup_result.shared) && pool->pf.discard_passdown) + remap_and_issue(tc, bio, lookup_result.block); + else + bio_endio(bio, 0); } break; @@ -2628,6 +2631,7 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv) if (tc->pool->pf.discard_enabled) { ti->discards_supported = 1; ti->num_discard_requests = 1; + ti->discard_zeroes_data_unsupported = 1; } dm_put(pool_md); |