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authorTejun Heo <tj@kernel.org>2012-02-08 09:19:38 +0100
committerJens Axboe <axboe@kernel.dk>2012-02-08 09:19:38 +0100
commit050c8ea80e3e90019d9e981c6a117ef614e882ed (patch)
treee1c53f17a93ba48b9aedb0c1560dfb022733845f /block
parent4e8670e26135d8fbfd5e084fddc1a8ed9f8eb4cb (diff)
downloadlinux-linaro-stable-050c8ea80e3e90019d9e981c6a117ef614e882ed.tar.gz
block: separate out blk_rq_merge_ok() and blk_try_merge() from elevator functions
blk_rq_merge_ok() is the elevator-neutral part of merge eligibility test. blk_try_merge() determines merge direction and expects the caller to have tested elv_rq_merge_ok() previously. elv_rq_merge_ok() now wraps blk_rq_merge_ok() and then calls elv_iosched_allow_merge(). elv_try_merge() is removed and the two callers are updated to call elv_rq_merge_ok() explicitly followed by blk_try_merge(). While at it, make rq_merge_ok() functions return bool. This is to prepare for plug merge update and doesn't introduce any behavior change. This is based on Jens' patch to skip elevator_allow_merge_fn() from plug merge. Signed-off-by: Tejun Heo <tj@kernel.org> LKML-Reference: <4F16F3CA.90904@kernel.dk> Original-patch-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-core.c4
-rw-r--r--block/blk-merge.c37
-rw-r--r--block/blk.h2
-rw-r--r--block/elevator.c55
4 files changed, 45 insertions, 53 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 532b3a21b383..fa697bf691eb 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1282,10 +1282,10 @@ static bool attempt_plug_merge(struct request_queue *q, struct bio *bio,
(*request_count)++;
- if (rq->q != q)
+ if (rq->q != q || !elv_rq_merge_ok(rq, bio))
continue;
- el_ret = elv_try_merge(rq, bio);
+ el_ret = blk_try_merge(rq, bio);
if (el_ret == ELEVATOR_BACK_MERGE) {
ret = bio_attempt_back_merge(q, rq, bio);
if (ret)
diff --git a/block/blk-merge.c b/block/blk-merge.c
index cfcc37cb222b..160035f54882 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -471,3 +471,40 @@ int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
{
return attempt_merge(q, rq, next);
}
+
+bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
+{
+ if (!rq_mergeable(rq))
+ return false;
+
+ /* don't merge file system requests and discard requests */
+ if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD))
+ return false;
+
+ /* don't merge discard requests and secure discard requests */
+ if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE))
+ return false;
+
+ /* different data direction or already started, don't merge */
+ if (bio_data_dir(bio) != rq_data_dir(rq))
+ return false;
+
+ /* must be same device and not a special request */
+ if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special)
+ return false;
+
+ /* only merge integrity protected bio into ditto rq */
+ if (bio_integrity(bio) != blk_integrity_rq(rq))
+ return false;
+
+ return true;
+}
+
+int blk_try_merge(struct request *rq, struct bio *bio)
+{
+ if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_sector)
+ return ELEVATOR_BACK_MERGE;
+ else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_sector)
+ return ELEVATOR_FRONT_MERGE;
+ return ELEVATOR_NO_MERGE;
+}
diff --git a/block/blk.h b/block/blk.h
index 7efd772336de..9c12f80882b0 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -137,6 +137,8 @@ int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
struct request *next);
void blk_recalc_rq_segments(struct request *rq);
void blk_rq_set_mixed_merge(struct request *rq);
+bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
+int blk_try_merge(struct request *rq, struct bio *bio);
void blk_queue_congestion_threshold(struct request_queue *q);
diff --git a/block/elevator.c b/block/elevator.c
index 91e18f8af9be..f016855a46b0 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -70,39 +70,9 @@ static int elv_iosched_allow_merge(struct request *rq, struct bio *bio)
/*
* can we safely merge with this request?
*/
-int elv_rq_merge_ok(struct request *rq, struct bio *bio)
+bool elv_rq_merge_ok(struct request *rq, struct bio *bio)
{
- if (!rq_mergeable(rq))
- return 0;
-
- /*
- * Don't merge file system requests and discard requests
- */
- if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD))
- return 0;
-
- /*
- * Don't merge discard requests and secure discard requests
- */
- if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE))
- return 0;
-
- /*
- * different data direction or already started, don't merge
- */
- if (bio_data_dir(bio) != rq_data_dir(rq))
- return 0;
-
- /*
- * must be same device and not a special request
- */
- if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special)
- return 0;
-
- /*
- * only merge integrity protected bio into ditto rq
- */
- if (bio_integrity(bio) != blk_integrity_rq(rq))
+ if (!blk_rq_merge_ok(rq, bio))
return 0;
if (!elv_iosched_allow_merge(rq, bio))
@@ -112,23 +82,6 @@ int elv_rq_merge_ok(struct request *rq, struct bio *bio)
}
EXPORT_SYMBOL(elv_rq_merge_ok);
-int elv_try_merge(struct request *__rq, struct bio *bio)
-{
- int ret = ELEVATOR_NO_MERGE;
-
- /*
- * we can merge and sequence is ok, check if it's possible
- */
- if (elv_rq_merge_ok(__rq, bio)) {
- if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector)
- ret = ELEVATOR_BACK_MERGE;
- else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector)
- ret = ELEVATOR_FRONT_MERGE;
- }
-
- return ret;
-}
-
static struct elevator_type *elevator_find(const char *name)
{
struct elevator_type *e;
@@ -478,8 +431,8 @@ int elv_merge(struct request_queue *q, struct request **req, struct bio *bio)
/*
* First try one-hit cache.
*/
- if (q->last_merge) {
- ret = elv_try_merge(q->last_merge, bio);
+ if (q->last_merge && elv_rq_merge_ok(q->last_merge, bio)) {
+ ret = blk_try_merge(q->last_merge, bio);
if (ret != ELEVATOR_NO_MERGE) {
*req = q->last_merge;
return ret;