From 5e7c4274a70aa2d6f485996d0ca1dad52d0039ca Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 3 Sep 2015 19:28:20 +0300 Subject: block: Check for gaps on front and back merges We are checking for gaps to previous bio_vec, which can only detect back merges gaps. Moreover, at the point where we check for a gap, we don't know if we will attempt a back or a front merge. Thus, check for gap to prev in a back merge attempt and check for a gap to next in a front merge attempt. Signed-off-by: Jens Axboe [sagig: Minor rename change] Signed-off-by: Sagi Grimberg --- block/blk-merge.c | 19 ++++++------------- include/linux/blkdev.h | 20 ++++++++++++++++++++ 2 files changed, 26 insertions(+), 13 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index cce23ba1ae5f..d9eddbc189f5 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -438,6 +438,8 @@ no_merge: int ll_back_merge_fn(struct request_queue *q, struct request *req, struct bio *bio) { + if (req_gap_back_merge(req, bio)) + return 0; if (blk_rq_sectors(req) + bio_sectors(bio) > blk_rq_get_max_sectors(req)) { req->cmd_flags |= REQ_NOMERGE; @@ -456,6 +458,9 @@ int ll_back_merge_fn(struct request_queue *q, struct request *req, int ll_front_merge_fn(struct request_queue *q, struct request *req, struct bio *bio) { + + if (req_gap_front_merge(req, bio)) + return 0; if (blk_rq_sectors(req) + bio_sectors(bio) > blk_rq_get_max_sectors(req)) { req->cmd_flags |= REQ_NOMERGE; @@ -482,14 +487,6 @@ static bool req_no_special_merge(struct request *req) return !q->mq_ops && req->special; } -static int req_gap_to_prev(struct request *req, struct bio *next) -{ - struct bio *prev = req->biotail; - - return bvec_gap_to_prev(req->q, &prev->bi_io_vec[prev->bi_vcnt - 1], - next->bi_io_vec[0].bv_offset); -} - static int ll_merge_requests_fn(struct request_queue *q, struct request *req, struct request *next) { @@ -504,7 +501,7 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req, if (req_no_special_merge(req) || req_no_special_merge(next)) return 0; - if (req_gap_to_prev(req, next->bio)) + if (req_gap_back_merge(req, next->bio)) return 0; /* @@ -712,10 +709,6 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio) !blk_write_same_mergeable(rq->bio, bio)) return false; - /* Only check gaps if the bio carries data */ - if (bio_has_data(bio) && req_gap_to_prev(rq, bio)) - return false; - return true; } diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index a622f270f09e..2ff94def041e 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1368,6 +1368,26 @@ static inline bool bvec_gap_to_prev(struct request_queue *q, ((bprv->bv_offset + bprv->bv_len) & queue_virt_boundary(q)); } +static inline bool bio_will_gap(struct request_queue *q, struct bio *prev, + struct bio *next) +{ + if (!bio_has_data(prev)) + return false; + + return bvec_gap_to_prev(q, &prev->bi_io_vec[prev->bi_vcnt - 1], + next->bi_io_vec[0].bv_offset); +} + +static inline bool req_gap_back_merge(struct request *req, struct bio *bio) +{ + return bio_will_gap(req->q, req->biotail, bio); +} + +static inline bool req_gap_front_merge(struct request *req, struct bio *bio) +{ + return bio_will_gap(req->q, bio, req->bio); +} + struct work_struct; int kblockd_schedule_work(struct work_struct *work); int kblockd_schedule_delayed_work(struct delayed_work *dwork, unsigned long delay); -- cgit