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-rw-r--r--block/blk-core.c19
-rw-r--r--block/cfq-iosched.c15
-rw-r--r--include/linux/elevator.h6
3 files changed, 13 insertions, 27 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index fa697bf691eb..3a78b00edd71 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 5684df6848bc..d0ba50533668 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);
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index d6dfb65c8885..7d4e0356f329 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -42,12 +42,6 @@ struct elevator_ops
elevator_merged_fn *elevator_merged_fn;
elevator_merge_req_fn *elevator_merge_req_fn;
elevator_allow_merge_fn *elevator_allow_merge_fn;
-
- /*
- * Used for both plugged list and elevator merging and in the
- * former case called without queue_lock. Read comment on top of
- * attempt_plug_merge() for details.
- */
elevator_bio_merged_fn *elevator_bio_merged_fn;
elevator_dispatch_fn *elevator_dispatch_fn;