diff options
Diffstat (limited to 'block/elevator.c')
| -rw-r--r-- | block/elevator.c | 37 |
1 files changed, 28 insertions, 9 deletions
diff --git a/block/elevator.c b/block/elevator.c index c0063f345c5..f6dafa8c7c4 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -51,6 +51,21 @@ static const int elv_hash_shift = 6; #define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash)) /* + * Query io scheduler to see if the current process issuing bio may be + * merged with rq. + */ +static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) +{ + request_queue_t *q = rq->q; + elevator_t *e = q->elevator; + + if (e->ops->elevator_allow_merge_fn) + return e->ops->elevator_allow_merge_fn(q, rq, bio); + + return 1; +} + +/* * can we safely merge with this request? */ inline int elv_rq_merge_ok(struct request *rq, struct bio *bio) @@ -65,12 +80,15 @@ inline int elv_rq_merge_ok(struct request *rq, struct bio *bio) return 0; /* - * same device and no special stuff set, merge is ok + * must be same device and not a special request */ - if (rq->rq_disk == bio->bi_bdev->bd_disk && !rq->special) - return 1; + if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) + return 0; - return 0; + if (!elv_iosched_allow_merge(rq, bio)) + return 0; + + return 1; } EXPORT_SYMBOL(elv_rq_merge_ok); @@ -572,6 +590,12 @@ void elv_insert(request_queue_t *q, struct request *rq, int where) */ rq->cmd_flags |= REQ_SOFTBARRIER; + /* + * Most requeues happen because of a busy condition, + * don't force unplug of the queue for that case. + */ + unplug_it = 0; + if (q->ordseq == 0) { list_add(&rq->queuelist, &q->queue_head); break; @@ -586,11 +610,6 @@ void elv_insert(request_queue_t *q, struct request *rq, int where) } list_add_tail(&rq->queuelist, pos); - /* - * most requeues happen because of a busy condition, don't - * force unplug of the queue for that case. - */ - unplug_it = 0; break; default: |