[systemd-devel] [PATCH] swap: introduce Discard property

[Zbigniew Jędrzejewski-Szmek]

On Mon, Sep 29, 2014 at 01:23:30PM +0200, Jan Synacek wrote:
> Jan Synacek <jsynacek at redhat.com> writes:
> > Zbigniew Jędrzejewski-Szmek <zbyszek at in.waw.pl> writes:
> >> On Wed, Sep 24, 2014 at 02:29:05PM +0200, Jan Synacek wrote:
> >>> Process possible "discard" values from /etc/fstab.
> >> Hm, wouldn't it be enough to simply pass through the options like with
> >> mounts, using the Options= option? This might be less work and be more
> >> flexible.
> >>
> >> Zbyszek
> >
> > Swap options are special in that they're processed and used by the
> > swapon(8) command. You cannot pass swapon -o <options>, as you can to
> > ordinary mounts. And how many options for swapon, that at the same time
> > can be specified in /etc/fstab, do we really care about? I'm not sure.
> 
> Ping, could anybody comment, please?
C'mon, it's been four days, two of that being the weekend.

But actually, I've been looking at your patch... and the situation is
"complicated". I now have a patch series which fixes a buglets in swap
support, but I got stuck on a one which I don't know how to work around.
Namely, we rely on being able to read back the settings of the swap device,
but there appears to be no way to do that for discard settings.

Zbyszek