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>
diff --git a/block/elevator.c b/block/elevator.c
index 91e18f8..f016855 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -70,39 +70,9 @@
/*
* 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 @@
}
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 @@
/*
* 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;