block: generic request_queue reference counting

[karo-tx-linux.git] / block / blk-core.c

diff --git a/block/blk-core.c b/block/blk-core.c
index 2eb722d48773cb8a8de49d58b934eed830755da7..9b4d735cb5b8bb2ead4b0dfd977f1e6ca21a9b2b 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -554,13 +554,10 @@ void blk_cleanup_queue(struct request_queue *q)
         * Drain all requests queued before DYING marking. Set DEAD flag to
         * prevent that q->request_fn() gets invoked after draining finished.
         */
-       if (q->mq_ops) {
-               blk_mq_freeze_queue(q);
-               spin_lock_irq(lock);
-       } else {
-               spin_lock_irq(lock);
+       blk_freeze_queue(q);
+       spin_lock_irq(lock);
+       if (!q->mq_ops)
                __blk_drain_queue(q, true);
-       }
        queue_flag_set(QUEUE_FLAG_DEAD, q);
        spin_unlock_irq(lock);
 
@@ -570,6 +567,7 @@ void blk_cleanup_queue(struct request_queue *q)
 
        if (q->mq_ops)
                blk_mq_free_queue(q);
+       percpu_ref_exit(&q->q_usage_counter);
 
        spin_lock_irq(lock);
        if (q->queue_lock != &q->__queue_lock)
@@ -629,6 +627,40 @@ struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
 }
 EXPORT_SYMBOL(blk_alloc_queue);
 
+int blk_queue_enter(struct request_queue *q, gfp_t gfp)
+{
+       while (true) {
+               int ret;
+
+               if (percpu_ref_tryget_live(&q->q_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;
+       }
+}
+
+void blk_queue_exit(struct request_queue *q)
+{
+       percpu_ref_put(&q->q_usage_counter);
+}
+
+static void blk_queue_usage_counter_release(struct percpu_ref *ref)
+{
+       struct request_queue *q =
+               container_of(ref, struct request_queue, q_usage_counter);
+
+       wake_up_all(&q->mq_freeze_wq);
+}
+
 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 {
        struct request_queue *q;
@@ -690,11 +722,22 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 
        init_waitqueue_head(&q->mq_freeze_wq);
 
-       if (blkcg_init_queue(q))
+       /*
+        * Init percpu_ref in atomic mode so that it's faster to shutdown.
+        * See blk_register_queue() for details.
+        */
+       if (percpu_ref_init(&q->q_usage_counter,
+                               blk_queue_usage_counter_release,
+                               PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
                goto fail_bdi;
 
+       if (blkcg_init_queue(q))
+               goto fail_ref;
+
        return q;
 
+fail_ref:
+       percpu_ref_exit(&q->q_usage_counter);
 fail_bdi:
        bdi_destroy(&q->backing_dev_info);
 fail_split:
@@ -1966,9 +2009,19 @@ void generic_make_request(struct bio *bio)
        do {
                struct request_queue *q = bdev_get_queue(bio->bi_bdev);
 
-               q->make_request_fn(q, bio);
+               if (likely(blk_queue_enter(q, __GFP_WAIT) == 0)) {
+
+                       q->make_request_fn(q, bio);
+
+                       blk_queue_exit(q);
 
-               bio = bio_list_pop(current->bio_list);
+                       bio = bio_list_pop(current->bio_list);
+               } else {
+                       struct bio *bio_next = bio_list_pop(current->bio_list);
+
+                       bio_io_error(bio);
+                       bio = bio_next;
+               }
        } while (bio);
        current->bio_list = NULL; /* deactivate */
 }