ceph: fix type promotion bug on 32bit systems

In this code "ret" is type long and "src_objlen" is unsigned int.  The
problem is that on 32bit systems, when we do the comparison signed longs
are type promoted to unsigned int.  So negative error codes from
do_splice_direct() are treated as success instead of failure.

Cc: stable@vger.kernel.org
Fixes: 1b0c3b9f91 ("ceph: re-org copy_file_range and fix some error paths")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/file.c

@@ -2969,7 +2969,7 @@ static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off,
 		ret = do_splice_direct(src_file, &src_off, dst_file,
 				       &dst_off, src_objlen, flags);
 		/* Abort on short copies or on error */
-		if (ret < src_objlen) {
+		if (ret < (long)src_objlen) {
 			dout("Failed partial copy (%zd)\n", ret);
 			goto out;
 		}