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| author | Martin K. Petersen <martin.petersen@oracle.com> | 2015-07-22 07:57:12 -0400 |
|---|---|---|
| committer | Sasha Levin <alexander.levin@verizon.com> | 2016-10-07 10:37:27 -0400 |
| commit | f6e672ada0c9714c7d1a63054ca98c707fa916d6 (patch) | |
| tree | 6ee8436c82e7f0e65c8bc91acd5c3bd6b140cc8d | |
| parent | 31714bce258a8b098d5629a88f61568c28bf8ca4 (diff) | |
| download | lwn-f6e672ada0c9714c7d1a63054ca98c707fa916d6.tar.gz lwn-f6e672ada0c9714c7d1a63054ca98c707fa916d6.zip | |
block: Do a full clone when splitting discard bios
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>
Cc: <stable@vger.kernel.org> # v3.14+
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
| -rw-r--r-- | block/bio.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/block/bio.c b/block/bio.c index 3e6e1986a5b2..78803e99c154 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1824,8 +1824,9 @@ 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) @@ -1835,7 +1836,15 @@ 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; |