Commit 943b40c8 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: respect queue limit of max discard segment 



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: 69840466 ("block: fix the DISCARD request merge")
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent bcb21c8c

block/blk-merge.c

+9 −2
Original line number Diff line number Diff line
@@ -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)