blk-mq: move hctx lock/unlock into a helper

BugLink: https://bugs.launchpad.net/bugs/1848739
Move the RCU vs SRCU logic into lock/unlock helpers, which makes
the actual functional bits within the locked region much easier
to read.

tj: Reordered in front of timeout revamp patches and added the missing
    blk_mq_run_hw_queue() conversion.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit 04ced159cec863f9bc27015d6b970bb13cfa6176)
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 6d9904ec32c43d7834416196565ec567e483c105..da42485cb39d954c475a078db62967e9a47772e7 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -580,6 +580,22 @@ static void __blk_mq_complete_request(struct request *rq)
        put_cpu();
 }
 
+static void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx)
+{
+       if (!(hctx->flags & BLK_MQ_F_BLOCKING))
+               rcu_read_unlock();
+       else
+               srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx);
+}
+
+static void hctx_lock(struct blk_mq_hw_ctx *hctx, int *srcu_idx)
+{
+       if (!(hctx->flags & BLK_MQ_F_BLOCKING))
+               rcu_read_lock();
+       else
+               *srcu_idx = srcu_read_lock(hctx->queue_rq_srcu);
+}
+
 /**
  * blk_mq_complete_request - end I/O on a request
  * @rq:                the request being processed
@@ -1266,17 +1282,11 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
         */
        WARN_ON_ONCE(in_interrupt());
 
-       if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
-               rcu_read_lock();
-               blk_mq_sched_dispatch_requests(hctx);
-               rcu_read_unlock();
-       } else {
-               might_sleep();
+       might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
 
-               srcu_idx = srcu_read_lock(hctx->queue_rq_srcu);
-               blk_mq_sched_dispatch_requests(hctx);
-               srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx);
-       }
+       hctx_lock(hctx, &srcu_idx);
+       blk_mq_sched_dispatch_requests(hctx);
+       hctx_unlock(hctx, srcu_idx);
 }
 
 static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
@@ -1374,17 +1384,10 @@ bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
         * And queue will be rerun in blk_mq_unquiesce_queue() if it is
         * quiesced.
         */
-       if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
-               rcu_read_lock();
-               need_run = !blk_queue_quiesced(hctx->queue) &&
-                       blk_mq_hctx_has_pending(hctx);
-               rcu_read_unlock();
-       } else {
-               srcu_idx = srcu_read_lock(hctx->queue_rq_srcu);
-               need_run = !blk_queue_quiesced(hctx->queue) &&
-                       blk_mq_hctx_has_pending(hctx);
-               srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx);
-       }
+       hctx_lock(hctx, &srcu_idx);
+       need_run = !blk_queue_quiesced(hctx->queue) &&
+               blk_mq_hctx_has_pending(hctx);
+       hctx_unlock(hctx, srcu_idx);
 
        if (need_run) {
                __blk_mq_delay_run_hw_queue(hctx, async, 0);
@@ -1696,7 +1699,7 @@ static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
 
 static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
                                        struct request *rq,
-                                       blk_qc_t *cookie, bool may_sleep)
+                                       blk_qc_t *cookie)
 {
        struct request_queue *q = rq->q;
        struct blk_mq_queue_data bd = {
@@ -1746,25 +1749,20 @@ static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
        }
 
 insert:
-       blk_mq_sched_insert_request(rq, false, run_queue, false, may_sleep);
+       blk_mq_sched_insert_request(rq, false, run_queue, false,
+                                       hctx->flags & BLK_MQ_F_BLOCKING);
 }
 
 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
                struct request *rq, blk_qc_t *cookie)
 {
-       if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
-               rcu_read_lock();
-               __blk_mq_try_issue_directly(hctx, rq, cookie, false);
-               rcu_read_unlock();
-       } else {
-               unsigned int srcu_idx;
+       int srcu_idx;
 
-               might_sleep();
+       might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
 
-               srcu_idx = srcu_read_lock(hctx->queue_rq_srcu);
-               __blk_mq_try_issue_directly(hctx, rq, cookie, true);
-               srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx);
-       }
+       hctx_lock(hctx, &srcu_idx);
+       __blk_mq_try_issue_directly(hctx, rq, cookie);
+       hctx_unlock(hctx, srcu_idx);
 }
 
 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)