Commit 050c8ea8 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe

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: default avatarTejun Heo <tj@kernel.org>
LKML-Reference: <4F16F3CA.90904@kernel.dk>
Original-patch-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 4e8670e2
......@@ -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)
......
......@@ -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;
}
......@@ -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);
......
......@@ -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;
......
......@@ -122,7 +122,6 @@ extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
extern void elv_add_request(struct request_queue *, struct request *, int);
extern void __elv_add_request(struct request_queue *, struct request *, int);
extern int elv_merge(struct request_queue *, struct request **, struct bio *);
extern int elv_try_merge(struct request *, struct bio *);
extern void elv_merge_requests(struct request_queue *, struct request *,
struct request *);
extern void elv_merged_request(struct request_queue *, struct request *, int);
......@@ -155,7 +154,7 @@ extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
extern int elevator_init(struct request_queue *, char *);
extern void elevator_exit(struct elevator_queue *);
extern int elevator_change(struct request_queue *, const char *);
extern int elv_rq_merge_ok(struct request *, struct bio *);
extern bool elv_rq_merge_ok(struct request *, struct bio *);
/*
* Helper functions.
......
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