[LTP] [PATCH v2 1/2] OVL_MNT: add setup_overlay helper

[Petr Vorel]

Hi Murphy,

> To create overlayfs dirs, and mount overlayfs if needed.

...
> +int setup_overlay(int mountovl)
> +{
> +	int ret;
> +
> +	/* Setup an overlay mount with lower dir and file */
> +	SAFE_MKDIR(OVL_LOWER, 0755);
> +	SAFE_MKDIR(OVL_UPPER, 0755);
> +	SAFE_MKDIR(OVL_WORK, 0755);
> +	SAFE_MKDIR(OVL_MNT, 0755);
> +
> +	/* Only create dirs, do not mount */
> +	if (mountovl == 0)
> +		return 0;
Instead of having int parameter, there could be create_overlay_dirs()
and mount_overlay(), which would call create_overlay_dirs().
(no need to lookup meaning of parameter).

> +
> +	ret = mount("overlay", OVL_MNT, "overlay", 0, "lowerdir="OVL_LOWER
> +		    ",upperdir="OVL_UPPER",workdir="OVL_WORK);
> +	if (ret < 0) {
> +		if (errno == ENODEV) {
> +			tst_res(TINFO,
> +				"overlayfs is not configured in this kernel.");
> +			return 1;
First I thought we'd implement it as a test flag (member of struct tst_test).
When we have it as separate function I wonder whether we could TCONF on ENODEV
instead of TINFO and return. Maybe there could be here for int strict parameter,
where 1 would be force safe (i.e. TCONF), otherwise only TINFO.
This could also to have SAFE_MOUNT_OVERLAY() macro which would use mount_overlay().
Similar approach as SAFE_SEND() and safe_send().

> +		}
> +		tst_brk(TBROK | TERRNO, "overlayfs mount failed");
> +	}
> +	return 0;
> +}

Kind regards,
Petr