Re: [Patch] Robustly search for ZFS labels & uberblocks

[Richard Laager]

On Sat, 2012-01-28 at 13:51 +0100, Vladimir 'φ-coder/phcoder' Serbinenko
wrote:
> > Index: grub/util/grub.d/10_linux.in
> > ===================================================================
> > --- grub.orig/util/grub.d/10_linux.in       2012-01-24 23:44:10.530591000 
> > -0600
> > +++ grub/util/grub.d/10_linux.in    2012-01-24 23:44:10.706928000 -0600
> > @@ -56,8 +56,10 @@
> >     LINUX_ROOT_DEVICE=UUID=${GRUB_DEVICE_UUID}
> >   fi
> >
> > -if [ "x`${grub_probe} --device ${GRUB_DEVICE} --target=fs 2>/dev/null || 
> > true`" = xbtrfs ] \
> > -    || [ "x`stat -f --printf=%T /`" = xbtrfs ]; then
> > +LINUX_ROOT_FS=`${grub_probe} --device ${GRUB_DEVICE} --target=fs 
> > 2>/dev/null || true`
> > +LINUX_ROOT_STAT=`stat -f --printf=%T / || true`
> > +
> > +if [ "x${LINUX_ROOT_FS}" = xbtrfs -o "x${LINUX_ROOT_STAT}" = xbtrfs ]; then
> >     rootsubvol="`make_system_path_relative_to_its_root /`"
> >     rootsubvol="${rootsubvol#/}"
> >     if [ "x${rootsubvol}" != x ]; then
> > @@ -76,6 +78,10 @@
> >       GRUB_CMDLINE_EXTRA="$GRUB_CMDLINE_EXTRA 
> > crashkernel=384M-2G:64M,2G-:128M"
> >   fi
> >
> > +if [ "x${LINUX_ROOT_FS}" = xzfs ]; then
> > +  GRUB_CMDLINE_LINUX="boot=zfs \$bootfs ${GRUB_CMDLINE_LINUX}"
> > +fi
> > +
> >   linux_entry ()
> >   {
> >     os="$1"
> > @@ -114,6 +120,12 @@
> >       fi
> >       printf '%s\n' "${prepare_boot_cache}"
> >     fi
> > +  if [ "x${LINUX_ROOT_FS}" = xzfs ]; then
> > +    cat<<  EOF
> > +   insmod zfsinfo
> > +   zfs-bootfs (\$root) bootfs
> This makes 3 wrong assumptions in a row:
> - / and /boot may be different.

Despite the variable being called LINUX_ROOT_FS, this is really the
output from grub-probe --device ${GRUB_DEVICE}. When / != /boot, is
$GRUB_DEVICE the device of / or /boot?

> - Linux may be in a non-root subvolume. Then the subvolid points to 
> wrong one.

By "Linux", you're talking about the kernel, as opposed to the root
filesystem, correct?

What do you mean by "non-root subvolume"? That sounds like a btrfs term,
not a ZFS term, so I don't follow.

> - / may be unaccessible to GRUB altogether.

Are you talking about at grub-install time or boot time? Can you provide
an example of when this might happen, so I can understand.

> In short: this command line part has to be generated on grub-mkconfig 
> time and have a stable representation. I'd recommend UUID and subvolume 
> name.

By "this command line part", are you talking about the path to the
kernel?

-- 
Richard

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