| From 12cd04412bc4ab5a52a612f6b6e67144ec7cd7ca Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Mon, 28 Jun 2021 10:33:12 +0800 |
| Subject: block: fix discard request merge |
| |
| From: Ming Lei <ming.lei@redhat.com> |
| |
| [ Upstream commit 2705dfb2094777e405e065105e307074af8965c1 ] |
| |
| ll_new_hw_segment() is reached only in case of single range discard |
| merge, and we don't have max discard segment size limit actually, so |
| it is wrong to run the following check: |
| |
| if (req->nr_phys_segments + nr_phys_segs > blk_rq_get_max_segments(req)) |
| |
| it may be always false since req->nr_phys_segments is initialized as |
| one, and bio's segment count is still 1, blk_rq_get_max_segments(reg) |
| is 1 too. |
| |
| Fix the issue by not doing the check and bypassing the calculation of |
| discard request's nr_phys_segments. |
| |
| Based on analysis from Wang Shanker. |
| |
| Cc: Christoph Hellwig <hch@lst.de> |
| Reported-by: Wang Shanker <shankerwangmiao@gmail.com> |
| Signed-off-by: Ming Lei <ming.lei@redhat.com> |
| Link: https://lore.kernel.org/r/20210628023312.1903255-1-ming.lei@redhat.com |
| Signed-off-by: Jens Axboe <axboe@kernel.dk> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| block/blk-merge.c | 8 ++++++-- |
| 1 file changed, 6 insertions(+), 2 deletions(-) |
| |
| diff --git a/block/blk-merge.c b/block/blk-merge.c |
| index 7cdd56696647..349cd7d3af81 100644 |
| --- a/block/blk-merge.c |
| +++ b/block/blk-merge.c |
| @@ -552,10 +552,14 @@ static inline unsigned int blk_rq_get_max_segments(struct request *rq) |
| static inline int ll_new_hw_segment(struct request *req, struct bio *bio, |
| unsigned int nr_phys_segs) |
| { |
| - if (req->nr_phys_segments + nr_phys_segs > blk_rq_get_max_segments(req)) |
| + if (blk_integrity_merge_bio(req->q, req, bio) == false) |
| goto no_merge; |
| |
| - if (blk_integrity_merge_bio(req->q, req, bio) == false) |
| + /* discard request merge won't add new segment */ |
| + if (req_op(req) == REQ_OP_DISCARD) |
| + return 1; |
| + |
| + if (req->nr_phys_segments + nr_phys_segs > blk_rq_get_max_segments(req)) |
| goto no_merge; |
| |
| /* |
| -- |
| 2.30.2 |
| |
