vfs: dentry_unhash immediately prior to rmdir

This presumes that there is no reason to unhash a dentry if we fail because
it is a mountpoint or the LSM check fails, and that the LSM checks do not
depend on the dentry being unhashed.
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -2564,24 +2564,24 @@ int vfs_rmdir(struct inode *dir, struct dentry *dentry)
 		return -EPERM;
 
 	mutex_lock(&dentry->d_inode->i_mutex);
-	dentry_unhash(dentry);
 	if (d_mountpoint(dentry))
 		error = -EBUSY;
 	else {
 		error = security_inode_rmdir(dir, dentry);
 		if (!error) {
+			dentry_unhash(dentry);
 			error = dir->i_op->rmdir(dir, dentry);
 			if (!error) {
 				dentry->d_inode->i_flags |= S_DEAD;
 				dont_mount(dentry);
 			}
+			dput(dentry);
 		}
 	}
 	mutex_unlock(&dentry->d_inode->i_mutex);
 	if (!error) {
 		d_delete(dentry);
 	}
-	dput(dentry);
 
 	return error;
 }