RFC: Pass TRIM through GELI

[Fabian Keil]

"Matthew D. Fuller" <fullermd at over-yonder.net> wrote:

> > > But that lack of checking is a Real Bug by itself anyway, so merits
> > > a fix.
> > Stuffed into bugzilla as
> > <https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=198860>
> 
> [...]
> 
> > After last round, everybody seems happy enough with this, so I've
> > filed it as
> > <https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=198863>.
> 
> Does anybody have outstanding concerns on these?  Or, if not, what
> else do we need to move them along?  They're working fine for me
> here...

One minor issue I ran into is that a patched kernel will
reject onetime requests from an unpatched userland:

$ geli version
kernel: 7
userland: 7
$ geli onetime -s 4096 /dev/gpt/swap-ada0
geli: Missing trim argument

If the update steps are:

1) Update kernel
2) Reboot
3) Update userland

the system will not be able to attach an encrypted swap partition
at step 2.

The culprit is:

@@ -256,12 +256,19 @@ g_eli_ctl_onetime(struct gctl_req *req, struct g_class *mp)
                gctl_error(req, "No '%s' argument.", "detach");
                return;
        }
+       trim = gctl_get_paraml(req, "trim", sizeof(*trim));
+       if (trim == NULL) {
+               gctl_error(req, "No '%s' argument.", "trim");
+               return;
+       }

This patch fixes this:
https://www.fabiankeil.de/sourcecode/electrobsd/geli-Accept-onetime-requests-from-userland-without-Trim-support.diff

BTW, the gctl_error() call is superfluous because it's already
called by gctl_get_paraml() and only the first error is recorded.
Looks like lots of gctl_error() calls in the file could be removed.

Fabian
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