Btrfs: do not strdup non existent strings

When we close devices we add back empty devices for some reason that escapes
me.  In the case of a missing dev we don't allocate an rcu_string for it's
name, so check to see if the device has a name and if it doesn't don't
bother strdup()'ing it.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b8708f994e6..3b394503bd4 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -569,9 +569,11 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
                 memcpy(new_device, device, sizeof(*new_device));
 
                 /* Safe because we are under uuid_mutex */
-                name = rcu_string_strdup(device->name->str, GFP_NOFS);
-                BUG_ON(device->name && !name); /* -ENOMEM */
-                rcu_assign_pointer(new_device->name, name);
+                if (device->name) {
+                        name = rcu_string_strdup(device->name->str, GFP_NOFS);
+                        BUG_ON(device->name && !name); /* -ENOMEM */
+                        rcu_assign_pointer(new_device->name, name);
+                }
                 new_device->bdev = NULL;
                 new_device->writeable = 0;
                 new_device->in_fs_metadata = 0;