ceph: fix compat_ioctl for ceph_dir_operations

The ceph_ioctl function is used both for files and directories, but only
the files support doing that in 32-bit compat mode.

On the s390 architecture, there is also a problem with invalid 31-bit
pointers that need to be passed through compat_ptr().

Use the new compat_ptr_ioctl() to address both issues.

Note: When backporting this patch to stable kernels, "compat_ioctl:
add compat_ptr_ioctl()" is needed as well.
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

fs/ceph/dir.c

@@ -1808,6 +1808,7 @@ const struct file_operations ceph_dir_fops = {
 	.open = ceph_open,
 	.release = ceph_release,
 	.unlocked_ioctl = ceph_ioctl,
+	.compat_ioctl = compat_ptr_ioctl,
 	.fsync = ceph_fsync,
 	.lock = ceph_lock,
 	.flock = ceph_flock,

fs/ceph/file.c

@@ -2162,7 +2162,7 @@ const struct file_operations ceph_file_fops = {
 	.splice_read = generic_file_splice_read,
 	.splice_write = iter_file_splice_write,
 	.unlocked_ioctl = ceph_ioctl,
-	.compat_ioctl	= ceph_ioctl,
+	.compat_ioctl = compat_ptr_ioctl,
 	.fallocate	= ceph_fallocate,
 	.copy_file_range = ceph_copy_file_range,
 };