ovl: support the FS_IOC_FS[SG]ETXATTR ioctls

They are the extended version of FS_IOC_FS[SG]ETFLAGS ioctls.
xfs_io -c "chattr <flags>" uses the new ioctls for setting flags.

This used to work in kernel pre v4.19, before stacked file ops
introduced the ovl_ioctl whitelist.
Reported-by: Dave Chinner <david@fromorbit.com>
Fixes: d1d04ef8 ("ovl: stack file ops")
Cc: <stable@vger.kernel.org> # v4.19
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/file.c

@@ -426,7 +426,8 @@ static unsigned int ovl_get_inode_flags(struct inode *inode)
 	return ovl_iflags;
 }
 
-static long ovl_ioctl_set_flags(struct file *file, unsigned long arg)
+static long ovl_ioctl_set_flags(struct file *file, unsigned int cmd,
+				unsigned long arg)
 {
 	long ret;
 	struct inode *inode = file_inode(file);
@@ -456,7 +457,7 @@ static long ovl_ioctl_set_flags(struct file *file, unsigned long arg)
 	if (ret)
 		goto unlock;
 
-	ret = ovl_real_ioctl(file, FS_IOC_SETFLAGS, arg);
+	ret = ovl_real_ioctl(file, cmd, arg);
 
 	ovl_copyflags(ovl_inode_real(inode), inode);
 unlock:
@@ -474,11 +475,13 @@ static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 
 	switch (cmd) {
 	case FS_IOC_GETFLAGS:
+	case FS_IOC_FSGETXATTR:
 		ret = ovl_real_ioctl(file, cmd, arg);
 		break;
 
 	case FS_IOC_SETFLAGS:
-		ret = ovl_ioctl_set_flags(file, arg);
+	case FS_IOC_FSSETXATTR:
+		ret = ovl_ioctl_set_flags(file, cmd, arg);
 		break;
 
 	default: