Code review comment for ~goneri/cloud-init:freebsd_mount_sync

On Mon, Mar 25, 2019 at 02:48:32PM -0000, Gonéri Le Bouder wrote:
> I'm actually not sure why we need the 'sync' option since the volume
> is supposed to be in RO mode.

mount_cb has a rw argument, so "the volume is supposed to be in RO mode"
isn't an accurate statement within that function.

> This is the reason why the uses of sync sounds more like a Linux
> specific work around. Since there is no real isolation, FreeBSD ends
> up with the parameter too and we have to ignore it. This is the reason
> why I took this approach: I enable it only on Linux, since it "may" be
> relevant there, I disable it everywhere else.

In the FreeBSD mount man page I pointed to ([0]), sync is a supported
mount option, so I don't believe that this should be Linux-specific.

[0] https://www.freebsd.org/cgi/man.cgi?mount(8)