Btrfs: Use btrfs_update_inode_fallback when creating a snapshot

On a really full file system I was getting ENOSPC back from
btrfs_update_inode when trying to update the parent inode when creating a
snapshot.  Just use the fallback method so we can update the inode and not
have to worry about having a delayed ref.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f92def2..5fc0990 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -94,8 +94,6 @@
 				   struct page *locked_page,
 				   u64 start, u64 end, int *page_started,
 				   unsigned long *nr_written, int unlock);
-static noinline int btrfs_update_inode_fallback(struct btrfs_trans_handle *trans,
-				struct btrfs_root *root, struct inode *inode);
 
 static int btrfs_init_inode_security(struct btrfs_trans_handle *trans,
 				     struct inode *inode,  struct inode *dir,
@@ -2746,8 +2744,9 @@
 	return btrfs_update_inode_item(trans, root, inode);
 }
 
-static noinline int btrfs_update_inode_fallback(struct btrfs_trans_handle *trans,
-				struct btrfs_root *root, struct inode *inode)
+noinline int btrfs_update_inode_fallback(struct btrfs_trans_handle *trans,
+					 struct btrfs_root *root,
+					 struct inode *inode)
 {
 	int ret;