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authorMartin K. Petersen <martin.petersen@oracle.com>2015-07-22 07:57:12 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-08-03 09:29:07 -0700
commitf7639d364c02eff91f433aca4e2d9ddaf37fb099 (patch)
tree22c3c84731d1b57385b4ee6a881837fe80ab84e3
parentadc7a64b2882aba125431dd22e4e364b71ff37c6 (diff)
block: Do a full clone when splitting discard bios
commit f3f5da624e0a891c34d8cd513c57f1d9b0c7dadc upstream. This fixes a data corruption bug when using discard on top of MD linear, raid0 and raid10 personalities. Commit 20d0189b1012 "block: Introduce new bio_split()" permits sharing the bio_vec between the two resulting bios. That is fine for read/write requests where the bio_vec is immutable. For discards, however, we need to be able to attach a payload and update the bio_vec so the page can get mapped to a scatterlist entry. Therefore the bio_vec can not be shared when splitting discards and we must do a full clone. Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Reported-by: Seunguk Shin <seunguk.shin@samsung.com> Tested-by: Seunguk Shin <seunguk.shin@samsung.com> Cc: Seunguk Shin <seunguk.shin@samsung.com> Cc: Jens Axboe <axboe@fb.com> Cc: Kent Overstreet <kent.overstreet@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--block/bio.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/block/bio.c b/block/bio.c
index f66a4eae16ee..4441522ca339 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1814,8 +1814,9 @@ EXPORT_SYMBOL(bio_endio_nodec);
* Allocates and returns a new bio which represents @sectors from the start of
* @bio, and updates @bio to represent the remaining sectors.
*
- * The newly allocated bio will point to @bio's bi_io_vec; it is the caller's
- * responsibility to ensure that @bio is not freed before the split.
+ * Unless this is a discard request the newly allocated bio will point
+ * to @bio's bi_io_vec; it is the caller's responsibility to ensure that
+ * @bio is not freed before the split.
*/
struct bio *bio_split(struct bio *bio, int sectors,
gfp_t gfp, struct bio_set *bs)
@@ -1825,7 +1826,15 @@ struct bio *bio_split(struct bio *bio, int sectors,
BUG_ON(sectors <= 0);
BUG_ON(sectors >= bio_sectors(bio));
- split = bio_clone_fast(bio, gfp, bs);
+ /*
+ * Discards need a mutable bio_vec to accommodate the payload
+ * required by the DSM TRIM and UNMAP commands.
+ */
+ if (bio->bi_rw & REQ_DISCARD)
+ split = bio_clone_bioset(bio, gfp, bs);
+ else
+ split = bio_clone_fast(bio, gfp, bs);
+
if (!split)
return NULL;