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block: respect queue limit of max discard segment

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When queue_max_discard_segments(q) is 1, blk_discard_mergable() will
return false for discard request, then normal request merge is applied.
However, only queue_max_segments() is checked, so max discard segment
limit isn't respected.

Check max discard segment limit in the request merge code for fixing
the issue.

Discard request failure of virtio_blk is fixed.

Fixes: 6984046608 ("block: fix the DISCARD request merge")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2020-08-17 17:52:39 +08:00 committed by Jens Axboe
parent bcb21c8cc9
commit 943b40c832
1 changed files with 9 additions and 2 deletions
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11
block/blk-merge.c
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@ -533,10 +533,17 @@ int __blk_rq_map_sg(struct request_queue *q, struct request *rq,
}
EXPORT_SYMBOL(__blk_rq_map_sg);
static inline unsigned int blk_rq_get_max_segments(struct request *rq)
{
if (req_op(rq) == REQ_OP_DISCARD)
return queue_max_discard_segments(rq->q);
return queue_max_segments(rq->q);
}
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 > queue_max_segments(req->q))
if (req->nr_phys_segments + nr_phys_segs > blk_rq_get_max_segments(req))
goto no_merge;
if (blk_integrity_merge_bio(req->q, req, bio) == false)
@ -624,7 +631,7 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
return 0;
total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
if (total_phys_segments > queue_max_segments(q))
if (total_phys_segments > blk_rq_get_max_segments(req))
return 0;
if (blk_integrity_merge_rq(q, req, next) == false)