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@xxxxxx>
Reported-by: Wang Shanker <shankerwangmiao@xxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
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 5c9d2a4ece86..a4afa488298e 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -559,10 +559,14 @@ 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;
/*
--
2.31.1
