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>
diff --git a/block/blk-merge.c b/block/blk-merge.c
index cce23ba..d9eddbc 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -438,6 +438,8 @@
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_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 @@
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 @@
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 @@
!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 a622f27..2ff94de 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1368,6 +1368,26 @@
((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);