block: only call ->request_fn when the queue is not stopped

Callers should use either blk_run_queue/__blk_run_queue, or
blk_start_queueing() to invoke request handling instead of calling
->request_fn() directly as that does not take the queue stopped
flag into account.

Also add appropriate comments on the above functions to detail
their usage.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 3 insertions, 4 deletions

diff --git a/block/elevator.c b/block/elevator.c
index 9482ffa1aae6..59173a69ebdf 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -612,7 +612,7 @@ void elv_insert(struct request_queue *q, struct request *rq, int where)
                  *   processing.
                  */
                 blk_remove_plug(q);
-                q->request_fn(q);
+                blk_start_queueing(q);
                 break;
 
         case ELEVATOR_INSERT_SORT:
@@ -950,7 +950,7 @@ void elv_completed_request(struct request_queue *q, struct request *rq)
                     blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN &&
                     blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) {
                         blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0);
-                        q->request_fn(q);
+                        blk_start_queueing(q);
                 }
         }
 }
@@ -1109,8 +1109,7 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
         elv_drain_elevator(q);
 
         while (q->rq.elvpriv) {
-                blk_remove_plug(q);
-                q->request_fn(q);
+                blk_start_queueing(q);
                 spin_unlock_irq(q->queue_lock);
                 msleep(10);
                 spin_lock_irq(q->queue_lock);