Re: grub2-probe confused by double bind mount?

[Chris Murphy]

On Tue, Aug 8, 2017 at 2:04 AM, Vladimir 'phcoder' Serbinenko
<address@hidden> wrote:
> Did you mount /proc ? What is the contents of /proc/self/mountinfo ?

/proc is mounted. The way these ostree environments get assembled is
super messy, and I can't be sure I'm truly assembling it exactly as
the OS installer does, because the installer isn't logging the chroot
commands. However, doing my own chroot to get a cat
/proc/self/mountinfo from inside the chroot, I get a grub-probe fail
only with Btrfs not ext4.


This is mountinfo inside the chroot, with Btrfs installation.
https://pastebin.com/d2twu4qi

This is mountinfo inside the chroot, with ext4 installation.
https://pastebin.com/vqyJiNz4

This is interleaving the two mountinfo outputs, Btrfs (top line) and
ext4 (bottom line), deleting the duplicates where the two match.
https://pastebin.com/nYX71ckR

OK so there are a few discrepancies I'm seeing in this 3rd paste
showing comparisons:

1. Neither one has / in the fifth column, for mountpoint. And yet this
doesn't cause a grub-probe problem in the ext4 case. Lines 7 and 8.

2. Each Btrfs case has /root/ as a prefix for column 4, that's the
name of the subvolume the installation is put into, so it should be
OK. grub2-probe doesn't have a problem with this when it's a
conventional non-ostree installation.

3. The one thing that is kinda screwy is the mountinfo for btrfs mount
options, shows a bogus subvol= path. The kernel code shows the correct
subvolid= in each case, but the multiple bind mounts ostree is doing
is causing the kernel code to *assume* those are subvolumes when in
fact they are not. There is only one legit subvolume on this
installation and that's a subvolume named "root". So all the other
subvol= paths are not really subvolumes. I hope that makes sense...

If grub-probe does not parse for subvol= then that's not likely the
problem here.



-- 
Chris Murphy