diff options
Diffstat (limited to 'block/cfq-iosched.c')
| -rw-r--r-- | block/cfq-iosched.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 533a2938ffd..9fc5eafa6c0 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, |