selftests/bpf: Copy file using read/write in local storage test

Splice (copy_file_range) doesn't work on all filesystems. I'm running
test kernels on top of my read-only disk image and it uses plan9 under the
hood. This prevents test_local_storage from successfully passing.

There is really no technical reason to use splice, so lets do
old-school read/write to copy file; this should work in all
environments.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201202174947.3621989-1-sdf@google.com

diff --git a/tools/testing/selftests/bpf/prog_tests/test_local_storage.c b/tools/testing/selftests/bpf/prog_tests/test_local_storage.c
index fcca7ba..c0fe73a 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/test_local_storage.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_local_storage.c
@@ -21,14 +21,6 @@ static inline int sys_pidfd_open(pid_t pid, unsigned int flags)
        return syscall(__NR_pidfd_open, pid, flags);
 }
 
-static inline ssize_t copy_file_range(int fd_in, loff_t *off_in, int fd_out,
-                                     loff_t *off_out, size_t len,
-                                     unsigned int flags)
-{
-       return syscall(__NR_copy_file_range, fd_in, off_in, fd_out, off_out,
-                      len, flags);
-}
-
 static unsigned int duration;
 
 #define TEST_STORAGE_VALUE 0xbeefdead
@@ -47,6 +39,7 @@ static int copy_rm(char *dest)
 {
        int fd_in, fd_out = -1, ret = 0;
        struct stat stat;
+       char *buf = NULL;
 
        fd_in = open("/bin/rm", O_RDONLY);
        if (fd_in < 0)
@@ -64,18 +57,33 @@ static int copy_rm(char *dest)
                goto out;
        }
 
-       ret = copy_file_range(fd_in, NULL, fd_out, NULL, stat.st_size, 0);
-       if (ret == -1) {
+       buf = malloc(stat.st_blksize);
+       if (!buf) {
                ret = -errno;
                goto out;
        }
 
+       while (ret = read(fd_in, buf, stat.st_blksize), ret > 0) {
+               ret = write(fd_out, buf, ret);
+               if (ret < 0) {
+                       ret = -errno;
+                       goto out;
+
+               }
+       }
+       if (ret < 0) {
+               ret = -errno;
+               goto out;
+
+       }
+
        /* Set executable permission on the copied file */
        ret = chmod(dest, 0100);
        if (ret == -1)
                ret = -errno;
 
 out:
+       free(buf);
        close(fd_in);
        close(fd_out);
        return ret;