Re: /etc/fstab rootfs options vs grub2 rootflags cmdline

[Andrei Borzenkov <arvidjaar@gmail.com>]

04.05.2016 18:54, Duncan пишет:
> Niccolò Belli posted on Wed, 04 May 2016 15:52:39 +0200 as excerpted:
> 
>> Thanks,
>> Now my fstab option are
>> rw,noatime,compress=lzo,discard,autodefrag,subvolid=257,subvol=/@
>> I tried to add rootflags=noatime,compress=lzo,discard,autodefrag to
>> GRUB_CMDLINE_LINUX in /etc/default/grub as you suggested but my system
>> didn't manage to boot, probably because grub automatically adds
>> rootflags=subvol=@ and only a single rootflags can be taken into
>> account.
>> Do you have any suggestion?
> 
> What about the subvol=/@?
> 
> I think if you specifically add your own rootflags, grub won't add its 
> own, and you said
> 

It will, but it will prepend it to GRUB_CMDLINE_LINUX and last
occurrence on kernel command line should win, so rootflags from
GRUB_CMDLINE_LINUX should be used.

> noatime,compress=lzo,discard,autodefrag
> 
> but left off the subvol=/@ (unless you simply forgot to put it in the 
> posting), and without that, it would have mounted the btrfs default 
> subvolume, which would be (the filesystem's) / (subvolid=5) if you 
> haven't changed it, and would have failed to boot as a result.
> 

But if I understand it correctly, GRUB already adds correct subvolume,
and none of listed options should cause failure to boot.