On Wed, Jun 09, 2021 at 08:45:55AM +0800, Ming Lei wrote:
> index 4d97fb6dd226..bcdff1879c34 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))
I'd rather handle this by returning UINT_MAX for discard requests from
blk_rq_get_max_segments given that bio_attempt_discard_merge is only used
for the !DISCARD_MERGE case anyway.
