diff options
| author | Mikulas Patocka <mpatocka@redhat.com> | 2012-07-27 15:08:03 +0100 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2012-07-27 15:08:03 +0100 |
| commit | 4929630901100fdbfa19186ecf5ea2706f57719b (patch) | |
| tree | d12aaec9ccae4fb91eb55271fc8f987db0bbce96 /drivers/md/dm-thin.c | |
| parent | 7acf0277cea0f2da89ffffcc9892bea23f618e63 (diff) | |
dm thin: split discards on block boundary
This patch sets the variable "ti->split_discard_requests" for the dm thin
target so that device mapper core splits discard requests on a block
boundary.
Consequently, a discard request that spans multiple blocks is never sent
to dm-thin. The patch also removes some code in process_discard that
deals with discards that span multiple blocks.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm-thin.c')
| -rw-r--r-- | drivers/md/dm-thin.c | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index f21d318d98f0..828649256902 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -1238,15 +1238,10 @@ static void process_discard(struct thin_c *tc, struct bio *bio) } } else { /* - * This path is hit if people are ignoring - * limits->discard_granularity. It ignores any - * part of the discard that is in a subsequent - * block. + * The DM core makes sure that the discard doesn't span + * a block boundary. So we submit the discard of a + * partial block appropriately. */ - sector_t offset = bio->bi_sector - (block * pool->sectors_per_block); - unsigned remaining = (pool->sectors_per_block - offset) << SECTOR_SHIFT; - bio->bi_size = min(bio->bi_size, remaining); - cell_release_singleton(cell, bio); cell_release_singleton(cell2, bio); if ((!lookup_result.shared) && pool->pf.discard_passdown) @@ -2509,7 +2504,8 @@ static void set_discard_limits(struct pool *pool, struct queue_limits *limits) /* * This is just a hint, and not enforced. We have to cope with - * bios that overlap 2 blocks. + * bios that cover a block partially. A discard that spans a block + * boundary is not sent to this target. */ limits->discard_granularity = pool->sectors_per_block << SECTOR_SHIFT; limits->discard_zeroes_data = pool->pf.zero_new_blocks; @@ -2652,6 +2648,8 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv) ti->discards_supported = 1; ti->num_discard_requests = 1; ti->discard_zeroes_data_unsupported = 1; + /* Discard requests must be split on a block boundary */ + ti->split_discard_requests = 1; } dm_put(pool_md); |