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;
/*