reiserfs: fix handling of -EOPNOTSUPP in reiserfs_for_each_xattr

Commit 60e4cf67 (reiserfs: fix extended attributes on the root
directory) introduced a regression open_xa_root started returning
-EOPNOTSUPP but it was not handled properly in reiserfs_for_each_xattr.

When the reiserfs module is built without CONFIG_REISERFS_FS_XATTR,
deleting an inode would result in a warning and chowning an inode
would also result in a warning and then fail to complete.

With CONFIG_REISERFS_FS_XATTR enabled, the xattr root would always be
present for read-write operations.

This commit handles -EOPNOSUPP in the same way -ENODATA is handled.

Fixes: 60e4cf67 ("reiserfs: fix extended attributes on the root directory")
CC: stable@vger.kernel.org	# Commit 60e4cf67 was picked up by stable
Link: https://lore.kernel.org/r/20200115180059.6935-1-jeffm@suse.comReported-by: Michael Brunnbauer <brunni@netestate.de>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/reiserfs/xattr.c

@@ -319,8 +319,12 @@ static int reiserfs_for_each_xattr(struct inode *inode,
 out_dir:
 	dput(dir);
 out:
-	/* -ENODATA isn't an error */
-	if (err == -ENODATA)
+	/*
+	 * -ENODATA: this object doesn't have any xattrs
+	 * -EOPNOTSUPP: this file system doesn't have xattrs enabled on disk.
+	 * Neither are errors
+	 */
+	if (err == -ENODATA || err == -EOPNOTSUPP)
 		err = 0;
 	return err;
 }