X-Git-Url: http://git.samba.org/samba.git/?p=sfrench%2Fcifs-2.6.git;a=blobdiff_plain;f=block%2Fblk-cgroup.c;fp=block%2Fblk-cgroup.c;h=88b1fce905200c1f2897598298733d7a0699aa9c;hp=8908298d6ad3f1ea4b04ac6b9f0ab9ad3d4c94d1;hb=0c9d338c8443b06da8e8d3bfce824c5ea6d3488f;hpb=fa5fa8ec6077a954e1aeb206fece15255b19e7b9

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 8908298d6ad3..88b1fce90520 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -634,6 +634,14 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 
 	q = bdev_get_queue(bdev);
 
+	/*
+	 * blkcg_deactivate_policy() requires queue to be frozen, we can grab
+	 * q_usage_counter to prevent concurrent with blkcg_deactivate_policy().
+	 */
+	ret = blk_queue_enter(q, 0);
+	if (ret)
+		return ret;
+
 	rcu_read_lock();
 	spin_lock_irq(&q->queue_lock);
 
@@ -703,6 +711,7 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 			goto success;
 	}
 success:
+	blk_queue_exit(q);
 	ctx->bdev = bdev;
 	ctx->blkg = blkg;
 	ctx->body = input;
@@ -715,6 +724,7 @@ fail_unlock:
 	rcu_read_unlock();
 fail:
 	blkdev_put_no_open(bdev);
+	blk_queue_exit(q);
 	/*
 	 * If queue was bypassing, we should retry.  Do so after a
 	 * short msleep().  It isn't strictly necessary but queue