NFS: Ensure we call nfs_sb_deactive() after releasing the directory inode

In order to avoid the "Busy inodes after unmount" error message, we need to
ensure that nfs_async_unlink_release() releases the super block after the
call to nfs_free_unlinkdata().

Signed-off-by: Trond Myklebust <[e-mail]>

fs/nfs/unlink.c

···
 static void nfs_async_unlink_release(void *calldata)
 {
 	struct nfs_unlinkdata	*data = calldata;
+	struct super_block *sb = data->dir->i_sb;
 
 	nfs_dec_sillycount(data->dir);
-	nfs_sb_deactive(NFS_SERVER(data->dir));
 	nfs_free_unlinkdata(data);
+	nfs_sb_deactive(NFS_SB(sb));
 }
 
 static const struct rpc_call_ops nfs_unlink_ops = {