xfs_io: fix copy_file_range symbol name collision

glibc 2.27 has a copy_file_range wrapper, so we need to change our
internal function out of the way to avoid compiler warnings.

Reported-by: fredrik@crux.nu
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

diff --git a/io/copy_file_range.c b/io/copy_file_range.c
index d1dfc5a..99fba20 100644
--- a/io/copy_file_range.c
+++ b/io/copy_file_range.c
@@ -42,13 +42,18 @@
 "));
 }
 
+/*
+ * Issue a raw copy_file_range syscall; for our test program we don't want the
+ * glibc buffered copy fallback.
+ */
 static loff_t
-copy_file_range(int fd, loff_t *src, loff_t *dst, size_t len)
+copy_file_range_cmd(int fd, loff_t *src, loff_t *dst, size_t len)
 {
 	loff_t ret;
 
 	do {
-		ret = syscall(__NR_copy_file_range, fd, src, file->fd, dst, len, 0);
+		ret = syscall(__NR_copy_file_range, fd, src, file->fd, dst,
+				len, 0);
 		if (ret == -1) {
 			perror("copy_range");
 			return errno;
@@ -130,7 +135,7 @@
 		copy_dst_truncate();
 	}
 
-	ret = copy_file_range(fd, &src, &dst, len);
+	ret = copy_file_range_cmd(fd, &src, &dst, len);
 	close(fd);
 	return ret;
 }