fs/ntfs3: fix an error code in ntfs_get_acl_ex()

The ntfs_get_ea() function returns negative error codes or on success
it returns the length.  In the original code a zero length return was
treated as -ENODATA and results in a NULL return.  But it should be
treated as an invalid length and result in an PTR_ERR(-EINVAL) return.

Fixes: be71b5c ("fs/ntfs3: Add attrib operations")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

fs/ntfs3/xattr.c

@@ -521,7 +521,7 @@ static struct posix_acl *ntfs_get_acl_ex(struct user_namespace *mnt_userns,
 		ni_unlock(ni);
 
 	/* Translate extended attribute to acl */
-	if (err > 0) {
+	if (err >= 0) {
 		acl = posix_acl_from_xattr(mnt_userns, buf, err);
 		if (!IS_ERR(acl))
 			set_cached_acl(inode, type, acl);