vfs: Fix the posix_acl_xattr_list return value

When a filesystem that contains POSIX ACLs is mounted without ACL support
(-o noacl), the appropriate behavior is not to list any existing POSIX ACL
xattrs.  The return value for list xattr handlers in this case is 0, not an
error code: several filesystems that use the POSIX ACL xattr handlers do
not expect the list operation to fail.

Symlinks cannot have ACLs, so posix_acl_xattr_list will never be called for
symlinks in the first place.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/posix_acl.c

@@ -833,9 +833,7 @@ posix_acl_xattr_list(struct dentry *dentry, char *list, size_t list_size,
 	size_t size;
 
 	if (!IS_POSIXACL(d_backing_inode(dentry)))
-		return -EOPNOTSUPP;
-	if (d_is_symlink(dentry))
-		return -EOPNOTSUPP;
+		return 0;
 
 	if (type == ACL_TYPE_ACCESS)
 		xname = POSIX_ACL_XATTR_ACCESS;