reiserfs: deal with NULL xattr root w/ xattrs disabled

This avoids an Oops in open_xa_root that can occur when deleting a file
with xattrs disabled.  It assumes that the xattr root will be there, and
that is not guaranteed.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/reiserfs/super.c

@@ -448,13 +448,11 @@ int remove_save_link(struct inode *inode, int truncate)
 static void reiserfs_kill_sb(struct super_block *s)
 {
 	if (REISERFS_SB(s)) {
-#ifdef CONFIG_REISERFS_FS_XATTR
 		if (REISERFS_SB(s)->xattr_root) {
 			d_invalidate(REISERFS_SB(s)->xattr_root);
 			dput(REISERFS_SB(s)->xattr_root);
 			REISERFS_SB(s)->xattr_root = NULL;
 		}
-#endif
 		if (REISERFS_SB(s)->priv_root) {
 			d_invalidate(REISERFS_SB(s)->priv_root);
 			dput(REISERFS_SB(s)->priv_root);

fs/reiserfs/xattr.c

@@ -123,7 +123,9 @@ static struct dentry *open_xa_root(struct super_block *sb, int flags)
 	mutex_lock_nested(&privroot->d_inode->i_mutex, I_MUTEX_XATTR);
 
 	xaroot = dget(REISERFS_SB(sb)->xattr_root);
-	if (!xaroot->d_inode) {
+	if (!xaroot)
+		xaroot = ERR_PTR(-ENODATA);
+	else if (!xaroot->d_inode) {
 		int err = -ENODATA;
 		if (xattr_may_create(flags))
 			err = xattr_mkdir(privroot->d_inode, xaroot, 0700);