Merge tag 'char-misc-4.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh...

[mirror_ubuntu-artful-kernel.git] / block / blk-mq.c

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 309e41087e6bac9638f0514e71b739570dac8c39..1c27b3eaef645ab1ff12d93ac400fcbdd3ebb655 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -78,47 +78,13 @@ static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
        clear_bit(CTX_TO_BIT(hctx, ctx), &bm->word);
 }
 
-static int blk_mq_queue_enter(struct request_queue *q, gfp_t gfp)
-{
-       while (true) {
-               int ret;
-
-               if (percpu_ref_tryget_live(&q->mq_usage_counter))
-                       return 0;
-
-               if (!(gfp & __GFP_WAIT))
-                       return -EBUSY;
-
-               ret = wait_event_interruptible(q->mq_freeze_wq,
-                               !atomic_read(&q->mq_freeze_depth) ||
-                               blk_queue_dying(q));
-               if (blk_queue_dying(q))
-                       return -ENODEV;
-               if (ret)
-                       return ret;
-       }
-}
-
-static void blk_mq_queue_exit(struct request_queue *q)
-{
-       percpu_ref_put(&q->mq_usage_counter);
-}
-
-static void blk_mq_usage_counter_release(struct percpu_ref *ref)
-{
-       struct request_queue *q =
-               container_of(ref, struct request_queue, mq_usage_counter);
-
-       wake_up_all(&q->mq_freeze_wq);
-}
-
 void blk_mq_freeze_queue_start(struct request_queue *q)
 {
        int freeze_depth;
 
        freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
        if (freeze_depth == 1) {
-               percpu_ref_kill(&q->mq_usage_counter);
+               percpu_ref_kill(&q->q_usage_counter);
                blk_mq_run_hw_queues(q, false);
        }
 }
@@ -126,18 +92,34 @@ EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start);
 
 static void blk_mq_freeze_queue_wait(struct request_queue *q)
 {
-       wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->mq_usage_counter));
+       wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
 }
 
 /*
  * Guarantee no request is in use, so we can change any data structure of
  * the queue afterward.
  */
-void blk_mq_freeze_queue(struct request_queue *q)
+void blk_freeze_queue(struct request_queue *q)
 {
+       /*
+        * In the !blk_mq case we are only calling this to kill the
+        * q_usage_counter, otherwise this increases the freeze depth
+        * and waits for it to return to zero.  For this reason there is
+        * no blk_unfreeze_queue(), and blk_freeze_queue() is not
+        * exported to drivers as the only user for unfreeze is blk_mq.
+        */
        blk_mq_freeze_queue_start(q);
        blk_mq_freeze_queue_wait(q);
 }
+
+void blk_mq_freeze_queue(struct request_queue *q)
+{
+       /*
+        * ...just an alias to keep freeze and unfreeze actions balanced
+        * in the blk_mq_* namespace
+        */
+       blk_freeze_queue(q);
+}
 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
 
 void blk_mq_unfreeze_queue(struct request_queue *q)
@@ -147,7 +129,7 @@ void blk_mq_unfreeze_queue(struct request_queue *q)
        freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
        WARN_ON_ONCE(freeze_depth < 0);
        if (!freeze_depth) {
-               percpu_ref_reinit(&q->mq_usage_counter);
+               percpu_ref_reinit(&q->q_usage_counter);
                wake_up_all(&q->mq_freeze_wq);
        }
 }
@@ -256,7 +238,7 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp,
        struct blk_mq_alloc_data alloc_data;
        int ret;
 
-       ret = blk_mq_queue_enter(q, gfp);
+       ret = blk_queue_enter(q, gfp);
        if (ret)
                return ERR_PTR(ret);
 
@@ -279,7 +261,7 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp,
        }
        blk_mq_put_ctx(ctx);
        if (!rq) {
-               blk_mq_queue_exit(q);
+               blk_queue_exit(q);
                return ERR_PTR(-EWOULDBLOCK);
        }
        return rq;
@@ -298,7 +280,7 @@ static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
 
        clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
        blk_mq_put_tag(hctx, tag, &ctx->last_tag);
-       blk_mq_queue_exit(q);
+       blk_queue_exit(q);
 }
 
 void blk_mq_free_hctx_request(struct blk_mq_hw_ctx *hctx, struct request *rq)
@@ -1185,11 +1167,7 @@ static struct request *blk_mq_map_request(struct request_queue *q,
        int rw = bio_data_dir(bio);
        struct blk_mq_alloc_data alloc_data;
 
-       if (unlikely(blk_mq_queue_enter(q, GFP_KERNEL))) {
-               bio_io_error(bio);
-               return NULL;
-       }
-
+       blk_queue_enter_live(q);
        ctx = blk_mq_get_ctx(q);
        hctx = q->mq_ops->map_queue(q, ctx->cpu);
 
@@ -2024,14 +2002,6 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
                hctxs[i]->queue_num = i;
        }
 
-       /*
-        * Init percpu_ref in atomic mode so that it's faster to shutdown.
-        * See blk_register_queue() for details.
-        */
-       if (percpu_ref_init(&q->mq_usage_counter, blk_mq_usage_counter_release,
-                           PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
-               goto err_hctxs;
-
        setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);
        blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
 
@@ -2112,8 +2082,6 @@ void blk_mq_free_queue(struct request_queue *q)
 
        blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
        blk_mq_free_hw_queues(q, set);
-
-       percpu_ref_exit(&q->mq_usage_counter);
 }
 
 /* Basically redo blk_mq_init_queue with queue frozen */