diff options
| author | Ming Lei <ming.lei@redhat.com> | 2026-01-10 16:42:36 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2026-01-10 20:22:54 +0300 |
| commit | f7ba87dfa8e42642d43faf29a71cee338086218b (patch) | |
| tree | ebe626be177fbfff3aa109f7d99bcdaaad938448 | |
| parent | a31bde687b10b1a3db9c61eba5abb662dda15277 (diff) | |
| download | linux-f7ba87dfa8e42642d43faf29a71cee338086218b.tar.xz | |
block: account for bi_bvec_done in bio_may_need_split()
When checking if a bio fits in a single segment, bio_may_need_split()
compares bi_size against the current bvec's bv_len. However, for
partially consumed bvecs (bi_bvec_done > 0), such as in cloned or
split bios, the remaining bytes in the current bvec is actually
(bv_len - bi_bvec_done), not bv_len.
This could cause bio_may_need_split() to incorrectly return false,
leading to nr_phys_segments being set to 1 when the bio actually
spans multiple segments. This triggers the WARN_ON in __blk_rq_map_sg()
when the actual mapped segments exceed the expected count.
Fix by subtracting bi_bvec_done from bv_len in the comparison.
Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Close: https://lore.kernel.org/linux-block/9687cf2b-1f32-44e1-b58d-2492dc6e7185@linux.ibm.com/
Repored-and-bisected-by: Christoph Hellwig <hch@infradead.org>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Tested-by: Christoph Hellwig <hch@infradead.org>
Fixes: ee623c892aa5 ("block: use bvec iterator helper for bio_may_need_split()")
Cc: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/blk.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/block/blk.h b/block/blk.h index 98f4dfd4ec75..980eef1f5690 100644 --- a/block/blk.h +++ b/block/blk.h @@ -380,7 +380,7 @@ static inline bool bio_may_need_split(struct bio *bio, return true; bv = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); - if (bio->bi_iter.bi_size > bv->bv_len) + if (bio->bi_iter.bi_size > bv->bv_len - bio->bi_iter.bi_bvec_done) return true; return bv->bv_len + bv->bv_offset > lim->max_fast_segment_size; } |