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authorJens Axboe <axboe@fb.com>2015-09-03 19:28:20 +0300
committerJens Axboe <axboe@fb.com>2015-09-03 10:33:09 -0600
commit5e7c4274a70aa2d6f485996d0ca1dad52d0039ca (patch)
treedce51421028d162af78514b631dc75a6be92cf11 /block
parent5fdb7e1b976dc9d18aff8c711e51d17c4c324a0e (diff)
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 <axboe@fb.com> [sagig: Minor rename change] Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Diffstat (limited to 'block')
-rw-r--r--block/blk-merge.c19
1 files changed, 6 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;
}