---

yaml
---
r: 359646
b: refs/heads/master
c: b82d167
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 6d292906f80170f4647079dd503df18b737750af
+refs/heads/master: b82d167be64b3e88d9434d8a98ce83c83a07aa48

trunk/drivers/block/rbd.c

@@ -261,10 +261,10 @@ struct rbd_device {
 
 	char			name[DEV_NAME_LEN]; /* blkdev name, e.g. rbd3 */
 
-	spinlock_t		lock;		/* queue lock */
+	spinlock_t		lock;		/* queue, flags, open_count */
 
 	struct rbd_image_header	header;
-	unsigned long		flags;
+	unsigned long		flags;		/* possibly lock protected */
 	struct rbd_spec		*spec;
 
 	char			*header_name;
@@ -289,13 +289,19 @@ struct rbd_device {
 
 	/* sysfs related */
 	struct device		dev;
-	unsigned long		open_count;
+	unsigned long		open_count;	/* protected by lock */
 };
 
-/* Flag bits for rbd_dev->flags */
-
+/*
+ * Flag bits for rbd_dev->flags.  If atomicity is required,
+ * rbd_dev->lock is used to protect access.
+ *
+ * Currently, only the "removing" flag (which is coupled with the
+ * "open_count" field) requires atomic access.
+ */
 enum rbd_dev_flags {
 	RBD_DEV_FLAG_EXISTS,	/* mapped snapshot has not been deleted */
+	RBD_DEV_FLAG_REMOVING,	/* this mapping is being removed */
 };
 
 static DEFINE_MUTEX(ctl_mutex);	  /* Serialize open/close/setup/teardown */
@@ -383,14 +389,23 @@ static int rbd_dev_v2_refresh(struct rbd_device *rbd_dev, u64 *hver);
 static int rbd_open(struct block_device *bdev, fmode_t mode)
 {
 	struct rbd_device *rbd_dev = bdev->bd_disk->private_data;
+	bool removing = false;
 
 	if ((mode & FMODE_WRITE) && rbd_dev->mapping.read_only)
 		return -EROFS;
 
+	spin_lock(&rbd_dev->lock);
+	if (test_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags))
+		removing = true;
+	else
+		rbd_dev->open_count++;
+	spin_unlock(&rbd_dev->lock);
+	if (removing)
+		return -ENOENT;
+
 	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
 	(void) get_device(&rbd_dev->dev);
 	set_device_ro(bdev, rbd_dev->mapping.read_only);
-	rbd_dev->open_count++;
 	mutex_unlock(&ctl_mutex);
 
 	return 0;
@@ -399,10 +414,14 @@ static int rbd_open(struct block_device *bdev, fmode_t mode)
 static int rbd_release(struct gendisk *disk, fmode_t mode)
 {
 	struct rbd_device *rbd_dev = disk->private_data;
+	unsigned long open_count_before;
+
+	spin_lock(&rbd_dev->lock);
+	open_count_before = rbd_dev->open_count--;
+	spin_unlock(&rbd_dev->lock);
+	rbd_assert(open_count_before > 0);
 
 	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
-	rbd_assert(rbd_dev->open_count > 0);
-	rbd_dev->open_count--;
 	put_device(&rbd_dev->dev);
 	mutex_unlock(&ctl_mutex);
 
@@ -4083,10 +4102,14 @@ static ssize_t rbd_remove(struct bus_type *bus,
 		goto done;
 	}
 
-	if (rbd_dev->open_count) {
+	spin_lock(&rbd_dev->lock);
+	if (rbd_dev->open_count)
 		ret = -EBUSY;
+	else
+		set_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags);
+	spin_unlock(&rbd_dev->lock);
+	if (ret < 0)
 		goto done;
-	}
 
 	rbd_remove_all_snaps(rbd_dev);
 	rbd_bus_del_dev(rbd_dev);