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authorJoe Thornber <ejt@redhat.com>2014-10-10 09:41:09 +0100
committerMike Snitzer <snitzer@redhat.com>2014-11-04 13:05:53 -0500
commitc822ed967cba38505713d59ed40a114386ef6c01 (patch)
treefe7f5014b55b2130615d699a80b04427b4f1d3c2 /drivers/md/dm-thin.c
parentd20c4b08be822ab1c5d333297f38f1b532d3febc (diff)
dm thin: grab a virtual cell before looking up the mapping
Avoids normal IO racing with discard. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
Diffstat (limited to 'drivers/md/dm-thin.c')
-rw-r--r--drivers/md/dm-thin.c16
1 files changed, 12 insertions, 4 deletions
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 4843801173fe..0f86d802b533 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -1936,6 +1936,14 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
return DM_MAPIO_SUBMITTED;
}
+ /*
+ * We must hold the virtual cell before doing the lookup, otherwise
+ * there's a race with discard.
+ */
+ build_virtual_key(tc->td, block, &key);
+ if (dm_bio_detain(tc->pool->prison, &key, bio, &cell1, &cell_result))
+ return DM_MAPIO_SUBMITTED;
+
r = dm_thin_find_block(td, block, 0, &result);
/*
@@ -1959,13 +1967,10 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
* shared flag will be set in their case.
*/
thin_defer_bio(tc, bio);
+ cell_defer_no_holder_no_free(tc, &cell1);
return DM_MAPIO_SUBMITTED;
}
- build_virtual_key(tc->td, block, &key);
- if (dm_bio_detain(tc->pool->prison, &key, bio, &cell1, &cell_result))
- return DM_MAPIO_SUBMITTED;
-
build_data_key(tc->td, result.block, &key);
if (dm_bio_detain(tc->pool->prison, &key, bio, &cell2, &cell_result)) {
cell_defer_no_holder_no_free(tc, &cell1);
@@ -1986,6 +1991,7 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
* of doing so.
*/
handle_unserviceable_bio(tc->pool, bio);
+ cell_defer_no_holder_no_free(tc, &cell1);
return DM_MAPIO_SUBMITTED;
}
/* fall through */
@@ -1996,6 +2002,7 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
* provide the hint to load the metadata into cache.
*/
thin_defer_bio(tc, bio);
+ cell_defer_no_holder_no_free(tc, &cell1);
return DM_MAPIO_SUBMITTED;
default:
@@ -2005,6 +2012,7 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
* pool is switched to fail-io mode.
*/
bio_io_error(bio);
+ cell_defer_no_holder_no_free(tc, &cell1);
return DM_MAPIO_SUBMITTED;
}
}