From 74f9cb3f8d5eb7a05b944ea10f4751a8c6b5b6f0 Mon Sep 17 00:00:00 2001
From: Alex Elder <elder@inktank.com>
Date: Fri, 16 Nov 2012 09:29:16 -0600
Subject: [PATCH] --- yaml --- r: 347610 b: refs/heads/master c:
 42382b709bd1d143b9f0fa93e0a3a1f2f4210707 h: refs/heads/master v: v3

---
 [refs]                    |  2 +-
 trunk/drivers/block/rbd.c | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index d14386adc97b..4230c3104d83 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8884d53dd63b1d9315b343564fcbe1ede004a99e
+refs/heads/master: 42382b709bd1d143b9f0fa93e0a3a1f2f4210707
diff --git a/trunk/drivers/block/rbd.c b/trunk/drivers/block/rbd.c
index 842caf4aab47..c7bf9613ad40 100644
--- a/trunk/drivers/block/rbd.c
+++ b/trunk/drivers/block/rbd.c
@@ -235,6 +235,7 @@ struct rbd_device {
 
 	/* sysfs related */
 	struct device		dev;
+	unsigned long		open_count;
 };
 
 static DEFINE_MUTEX(ctl_mutex);	  /* Serialize open/close/setup/teardown */
@@ -309,8 +310,11 @@ static int rbd_open(struct block_device *bdev, fmode_t mode)
 	if ((mode & FMODE_WRITE) && rbd_dev->mapping.read_only)
 		return -EROFS;
 
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
 	rbd_get_dev(rbd_dev);
 	set_device_ro(bdev, rbd_dev->mapping.read_only);
+	rbd_dev->open_count++;
+	mutex_unlock(&ctl_mutex);
 
 	return 0;
 }
@@ -319,7 +323,11 @@ static int rbd_release(struct gendisk *disk, fmode_t mode)
 {
 	struct rbd_device *rbd_dev = disk->private_data;
 
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+	rbd_assert(rbd_dev->open_count > 0);
+	rbd_dev->open_count--;
 	rbd_put_dev(rbd_dev);
+	mutex_unlock(&ctl_mutex);
 
 	return 0;
 }
@@ -3745,6 +3753,11 @@ static ssize_t rbd_remove(struct bus_type *bus,
 		goto done;
 	}
 
+	if (rbd_dev->open_count) {
+		ret = -EBUSY;
+		goto done;
+	}
+
 	rbd_remove_all_snaps(rbd_dev);
 	rbd_bus_del_dev(rbd_dev);