Mailinglist Archive: yast-devel (42 mails)

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Re: [yast-devel] openQA broken for Storage-NG
On 04/18/2017 10:07 AM, Stefan Hundhammer wrote:
On 2017-04-17 13:06, Ancor Gonzalez Sosa wrote:
I don't think is related to snapshots, but to some btrfs wizardly I fail
to understand.

I compared a working TW (yast-storage) and our ISO (yast-storage-ng).

With our ISO
============

1) At the end of installation, before bootloader is installed/configured

- /dev/sda1 is mounted on /mnt and contains an empty boot/grub2/i386-pc
- The corresponding subvol is mounted at /mnt/boot/grub2/i386-pc
- The subvolume is empty as well

2) During the bootloader installation

- /mnt/boot/grub2/i386-pc is populated with several files.

3) When the system is about to restart and everything is unmounted, you
can do this checks:

# First check
mount /dev/sda1 /mnt
ls /mnt/boot/grub2/i386-pc
# Result: no files there

# Second check (after umounting the previous)
mount /dev/sda1 /mnt
mount -o subvol=/@/boot/grub2/i386-pc /dev/sda1 /mnt/boot/grub2/i386-pc
ls /mnt/boot/grub2/i386-pc
# Result: the files are there, as expected

That sounds like the subvolume was not mounted while grub2 was written:
Obviously the files went to the toplevel subvolume or to no subvolume at
all (is this possible?), not to the correct subvolume.

Not really. In this case, the files were actually written in the
subvolume, but NOT in the toplevel subvolume. That's why booting is failing.

In the successful case (TW), the files were available also if the
subvolume was not mounted.

Or maybe the subvolume was not mounted with the correct mount options
("-o subvol=...")? But that would mean that that mount had silently failed.
Or did it complain, and we just didn't react to the error properly?

As far as I was able to see, the subvolume was mounted with the right
options in both cases (TW and StorageNG) during the whole installation
process.

Conclusions:

1) I don't understand btrfs (time for some reading!)
2) Something is different in the way subvolumes are created/managed in
both cases.

Both options were not exclusive. ;-)

I assume 2).

Now the question is "what is different?"

Cheers.

--
Ancor González Sosa
YaST Team at SUSE Linux GmbH
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