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>
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4e8670e261
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5 changed files with 46 additions and 55 deletions
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@ -1282,10 +1282,10 @@ static bool attempt_plug_merge(struct request_queue *q, struct bio *bio,
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(*request_count)++;
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if (rq->q != q)
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if (rq->q != q || !elv_rq_merge_ok(rq, bio))
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continue;
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el_ret = elv_try_merge(rq, bio);
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el_ret = blk_try_merge(rq, bio);
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if (el_ret == ELEVATOR_BACK_MERGE) {
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ret = bio_attempt_back_merge(q, rq, bio);
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if (ret)
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@ -471,3 +471,40 @@ int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
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{
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return attempt_merge(q, rq, next);
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}
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bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
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{
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if (!rq_mergeable(rq))
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return false;
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/* don't merge file system requests and discard requests */
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if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD))
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return false;
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/* don't merge discard requests and secure discard requests */
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if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE))
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return false;
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/* different data direction or already started, don't merge */
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if (bio_data_dir(bio) != rq_data_dir(rq))
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return false;
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/* must be same device and not a special request */
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if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special)
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return false;
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/* only merge integrity protected bio into ditto rq */
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if (bio_integrity(bio) != blk_integrity_rq(rq))
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return false;
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return true;
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}
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int blk_try_merge(struct request *rq, struct bio *bio)
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{
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if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_sector)
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return ELEVATOR_BACK_MERGE;
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else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_sector)
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return ELEVATOR_FRONT_MERGE;
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return ELEVATOR_NO_MERGE;
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}
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@ -137,6 +137,8 @@ int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
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struct request *next);
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void blk_recalc_rq_segments(struct request *rq);
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void blk_rq_set_mixed_merge(struct request *rq);
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bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
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int blk_try_merge(struct request *rq, struct bio *bio);
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void blk_queue_congestion_threshold(struct request_queue *q);
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@ -70,39 +70,9 @@ static int elv_iosched_allow_merge(struct request *rq, struct bio *bio)
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/*
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* can we safely merge with this request?
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*/
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int elv_rq_merge_ok(struct request *rq, struct bio *bio)
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bool elv_rq_merge_ok(struct request *rq, struct bio *bio)
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{
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if (!rq_mergeable(rq))
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return 0;
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/*
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* Don't merge file system requests and discard requests
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*/
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if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD))
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return 0;
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/*
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* Don't merge discard requests and secure discard requests
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*/
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if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE))
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return 0;
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/*
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* different data direction or already started, don't merge
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*/
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if (bio_data_dir(bio) != rq_data_dir(rq))
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return 0;
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/*
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* must be same device and not a special request
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*/
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if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special)
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return 0;
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/*
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* only merge integrity protected bio into ditto rq
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*/
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if (bio_integrity(bio) != blk_integrity_rq(rq))
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if (!blk_rq_merge_ok(rq, bio))
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return 0;
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if (!elv_iosched_allow_merge(rq, bio))
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@ -112,23 +82,6 @@ int elv_rq_merge_ok(struct request *rq, struct bio *bio)
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}
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EXPORT_SYMBOL(elv_rq_merge_ok);
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int elv_try_merge(struct request *__rq, struct bio *bio)
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{
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int ret = ELEVATOR_NO_MERGE;
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/*
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* we can merge and sequence is ok, check if it's possible
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*/
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if (elv_rq_merge_ok(__rq, bio)) {
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if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector)
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ret = ELEVATOR_BACK_MERGE;
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else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector)
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ret = ELEVATOR_FRONT_MERGE;
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}
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return ret;
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}
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static struct elevator_type *elevator_find(const char *name)
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{
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struct elevator_type *e;
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@ -478,8 +431,8 @@ int elv_merge(struct request_queue *q, struct request **req, struct bio *bio)
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/*
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* First try one-hit cache.
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*/
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if (q->last_merge) {
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ret = elv_try_merge(q->last_merge, bio);
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if (q->last_merge && elv_rq_merge_ok(q->last_merge, bio)) {
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ret = blk_try_merge(q->last_merge, bio);
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if (ret != ELEVATOR_NO_MERGE) {
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*req = q->last_merge;
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return ret;
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@ -122,7 +122,6 @@ extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
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extern void elv_add_request(struct request_queue *, struct request *, int);
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extern void __elv_add_request(struct request_queue *, struct request *, int);
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extern int elv_merge(struct request_queue *, struct request **, struct bio *);
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extern int elv_try_merge(struct request *, struct bio *);
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extern void elv_merge_requests(struct request_queue *, struct request *,
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struct request *);
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extern void elv_merged_request(struct request_queue *, struct request *, int);
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@ -155,7 +154,7 @@ extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
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extern int elevator_init(struct request_queue *, char *);
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extern void elevator_exit(struct elevator_queue *);
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extern int elevator_change(struct request_queue *, const char *);
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extern int elv_rq_merge_ok(struct request *, struct bio *);
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extern bool elv_rq_merge_ok(struct request *, struct bio *);
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/*
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* Helper functions.
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