[LTP] [PATCH] syscalls/statx01: Add stx_mnt_id check

[Cyril Hrubis]

Hi!
> +static int file_fd = -1;
> +
> +#ifdef HAVE_STRUCT_STATX_STX_MNT_ID
> +static void test_mnt_id(struct statx *buf)
> +{
> +	FILE *file;
> +	char line[PATH_MAX];
> +	int pid;
> +	unsigned int line_mjr, line_mnr, mnt_id;

Shouldn't we check the STATX_MNT_ID bit here before we event attempt to
continue? Otherwise if we compile the test with headers where stx_mnt_id
is defined then run it on old kernel there will be garbage in the
stx_mnt_id field.

> +	file = SAFE_FOPEN("/proc/self/mountinfo", "r");
> +
> +	while (fgets(line, sizeof(line), file)) {
> +		if (sscanf(line, "%d %*d %d:%d", &mnt_id, &line_mjr, &line_mnr) != 3)
> +			continue;
> +
> +		if (line_mjr == buf->stx_dev_major && line_mnr == buf->stx_dev_minor)
> +			break;
> +	}
> +
> +	SAFE_FCLOSE(file);
> +
> +	if (buf->stx_mnt_id == mnt_id)
> +		tst_res(TPASS,
> +			"statx.stx_mnt_id equals to mount_id(%d) in /proc/self/mountinfo",
> +			mnt_id);
> +	else
> +		tst_res(TFAIL,
> +			"statx.stx_mnt_id(%d) is different from mount_id(%d) in /proc/self/mountinfo",
> +			buf->stx_mnt_id, mnt_id);
> +
> +	pid = getpid();
> +	snprintf(line, PATH_MAX, "/proc/%d/fdinfo/%d", pid, file_fd);
> +	TST_ASSERT_FILE_INT(line, "mnt_id:", buf->stx_mnt_id);
> +}
> +#endif
> +
>  static void test_normal_file(void)
>  {
>  	struct statx buff;
> @@ -106,6 +146,11 @@ static void test_normal_file(void)
>  		tst_res(TFAIL, "stx_nlink(%u) is different from expected(1)",
>  			buff.stx_nlink);
>  
> +#ifdef HAVE_STRUCT_STATX_STX_MNT_ID
> +	test_mnt_id(&buff);
> +#else
> +	tst_res(TCONF, "stx_mnt_id was not supported until linux 5.8.");

This is confusing at best, if we end up here we were missing the
structure member during compilation regardless the kernel version.

So this message really should be:

"stx_mnt_id not defined in struct statx"


-- 
Cyril Hrubis
chrubis@suse.cz