diff options
| -rw-r--r-- | block/cfq-iosched.c | 33 | ||||
| -rw-r--r-- | block/elevator.c | 26 | ||||
| -rw-r--r-- | include/linux/elevator.h | 3 |
3 files changed, 58 insertions, 4 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 533a293..9fc5eaf 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -568,6 +568,38 @@ cfq_merged_requests(request_queue_t *q, struct request *rq, cfq_remove_request(next); } +static int cfq_allow_merge(request_queue_t *q, struct request *rq, + struct bio *bio) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + const int rw = bio_data_dir(bio); + struct cfq_queue *cfqq; + pid_t key; + + /* + * If bio is async or a write, always allow merge + */ + if (!bio_sync(bio) || rw == WRITE) + return 1; + + /* + * bio is sync. if request is not, disallow. + */ + if (!rq_is_sync(rq)) + return 0; + + /* + * Ok, both bio and request are sync. Allow merge if they are + * from the same queue. + */ + key = cfq_queue_pid(current, rw, 1); + cfqq = cfq_find_cfq_hash(cfqd, key, current->ioprio); + if (cfqq != RQ_CFQQ(rq)) + return 0; + + return 1; +} + static inline void __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) { @@ -2125,6 +2157,7 @@ static struct elevator_type iosched_cfq = { .elevator_merge_fn = cfq_merge, .elevator_merged_fn = cfq_merged_request, .elevator_merge_req_fn = cfq_merged_requests, + .elevator_allow_merge_fn = cfq_allow_merge, .elevator_dispatch_fn = cfq_dispatch_requests, .elevator_add_req_fn = cfq_insert_request, .elevator_activate_req_fn = cfq_activate_request, diff --git a/block/elevator.c b/block/elevator.c index c0063f3..62c7a30 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); diff --git a/include/linux/elevator.h b/include/linux/elevator.h index a24931d..e88fcbc 100644 --- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -12,6 +12,8 @@ typedef void (elevator_merge_req_fn) (request_queue_t *, struct request *, struc typedef void (elevator_merged_fn) (request_queue_t *, struct request *, int); +typedef int (elevator_allow_merge_fn) (request_queue_t *, struct request *, struct bio *); + typedef int (elevator_dispatch_fn) (request_queue_t *, int); typedef void (elevator_add_req_fn) (request_queue_t *, struct request *); @@ -33,6 +35,7 @@ struct elevator_ops elevator_merge_fn *elevator_merge_fn; elevator_merged_fn *elevator_merged_fn; elevator_merge_req_fn *elevator_merge_req_fn; + elevator_allow_merge_fn *elevator_allow_merge_fn; elevator_dispatch_fn *elevator_dispatch_fn; elevator_add_req_fn *elevator_add_req_fn; |
