eCryptfs: Clear i_nlink in rmdir

eCryptfs wasn't clearing the eCryptfs inode's i_nlink after a successful
vfs_rmdir() on the lower directory. This resulted in the inode evict and
destroy paths to be missed.

https://bugs.launchpad.net/ecryptfs/+bug/723518Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
Cc: <stable@kernel.org>

fs/ecryptfs/inode.c

@@ -527,6 +527,8 @@ static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
 	dget(lower_dentry);
 	rc = vfs_rmdir(lower_dir_dentry->d_inode, lower_dentry);
 	dput(lower_dentry);
+	if (!rc && dentry->d_inode)
+		clear_nlink(dentry->d_inode);
 	fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
 	dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
 	unlock_dir(lower_dir_dentry);