Commit c822ed96 authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer

dm thin: grab a virtual cell before looking up the mapping

Avoids normal IO racing with discard.
Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
parent d20c4b08
......@@ -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;
}
}
......
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