Btrfs: fix NULL pointer crash of deleting a seed device

Liu Bo · masoncl · commit 29cc83f69c83 · 2014-06-09T17:20:47.000-07:00
Same as normal devices, seed devices should be initialized with
fs_info-&gt;dev_root as well, otherwise we'll get a NULL pointer crash.

Cc: Chris Murphy &lt;lists@colorremedies.com&gt;
Reported-by: Chris Murphy &lt;lists@colorremedies.com&gt;
Signed-off-by: Liu Bo &lt;bo.li.liu@oracle.com&gt;
Signed-off-by: Chris Mason &lt;clm@fb.com&gt;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
@@ -6146,10 +6146,14 @@ void btrfs_init_devices_late(struct btrfs_fs_info *fs_info)
 	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 	struct btrfs_device *device;
 
-	mutex_lock(&fs_devices->device_list_mutex);
-	list_for_each_entry(device, &fs_devices->devices, dev_list)
-		device->dev_root = fs_info->dev_root;
-	mutex_unlock(&fs_devices->device_list_mutex);
+	while (fs_devices) {
+		mutex_lock(&fs_devices->device_list_mutex);
+		list_for_each_entry(device, &fs_devices->devices, dev_list)
+			device->dev_root = fs_info->dev_root;
+		mutex_unlock(&fs_devices->device_list_mutex);
+
+		fs_devices = fs_devices->seed;
+	}
 }
 
 static void __btrfs_reset_dev_stats(struct btrfs_device *dev)
