diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-core.c | 19 | ||||
| -rw-r--r-- | block/cfq-iosched.c | 15 |
2 files changed, 13 insertions, 21 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index fa697bf691e..3a78b00edd7 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1212,7 +1212,6 @@ static bool bio_attempt_back_merge(struct request_queue *q, struct request *req, req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); drive_stat_acct(req, 0); - elv_bio_merged(q, req, bio); return true; } @@ -1243,7 +1242,6 @@ static bool bio_attempt_front_merge(struct request_queue *q, req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); drive_stat_acct(req, 0); - elv_bio_merged(q, req, bio); return true; } @@ -1257,13 +1255,12 @@ static bool bio_attempt_front_merge(struct request_queue *q, * on %current's plugged list. Returns %true if merge was successful, * otherwise %false. * - * This function is called without @q->queue_lock; however, elevator is - * accessed iff there already are requests on the plugged list which in - * turn guarantees validity of the elevator. - * - * Note that, on successful merge, elevator operation - * elevator_bio_merged_fn() will be called without queue lock. Elevator - * must be ready for this. + * Plugging coalesces IOs from the same issuer for the same purpose without + * going through @q->queue_lock. As such it's more of an issuing mechanism + * than scheduling, and the request, while may have elvpriv data, is not + * added on the elevator at this point. In addition, we don't have + * reliable access to the elevator outside queue lock. Only check basic + * merging parameters without querying the elevator. */ static bool attempt_plug_merge(struct request_queue *q, struct bio *bio, unsigned int *request_count) @@ -1282,7 +1279,7 @@ static bool attempt_plug_merge(struct request_queue *q, struct bio *bio, (*request_count)++; - if (rq->q != q || !elv_rq_merge_ok(rq, bio)) + if (rq->q != q || !blk_rq_merge_ok(rq, bio)) continue; el_ret = blk_try_merge(rq, bio); @@ -1347,12 +1344,14 @@ void blk_queue_bio(struct request_queue *q, struct bio *bio) el_ret = elv_merge(q, &req, bio); if (el_ret == ELEVATOR_BACK_MERGE) { if (bio_attempt_back_merge(q, req, bio)) { + elv_bio_merged(q, req, bio); if (!attempt_back_merge(q, req)) elv_merged_request(q, req, el_ret); goto out_unlock; } } else if (el_ret == ELEVATOR_FRONT_MERGE) { if (bio_attempt_front_merge(q, req, bio)) { + elv_bio_merged(q, req, bio); if (!attempt_front_merge(q, req)) elv_merged_request(q, req, el_ret); goto out_unlock; diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 5684df6848b..d0ba5053366 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1699,18 +1699,11 @@ static int cfq_allow_merge(struct request_queue *q, struct request *rq, /* * Lookup the cfqq that this bio will be queued with and allow - * merge only if rq is queued there. This function can be called - * from plug merge without queue_lock. In such cases, ioc of @rq - * and %current are guaranteed to be equal. Avoid lookup which - * requires queue_lock by using @rq's cic. + * merge only if rq is queued there. */ - if (current->io_context == RQ_CIC(rq)->icq.ioc) { - cic = RQ_CIC(rq); - } else { - cic = cfq_cic_lookup(cfqd, current->io_context); - if (!cic) - return false; - } + cic = cfq_cic_lookup(cfqd, current->io_context); + if (!cic) + return false; cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); return cfqq == RQ_CFQQ(rq); |