Re: No space left errors on shutdown with systemd-homed /home dir

[Wang Yugui <wangyugui@e16-tech.com>]

Hi,

> Why 'resize image size 128.0G → 1.8G'?
> 
> This 'No space left errors ' happen when 'resize image size 128.0G → 1.8G'.
> and it will not happen when ''resize image size 128.0G → 2.0G'?

'btrfs filesystem resize' and kernel btrfs_shrink_device() now does not
check whether the new shrinked size is too small.

if a too small shrinked size is specified to 'btrfs filesystem resize',
a same call trace will happen.

the min shrinkable size is in the unit of btrfs chunk, not the unit of btrfs
blockt.
This value is a little difficult to get correctly, so we need a new
feature such as 'btrfs filesystem resize min' in addition to 
the exist 'btrfs filesystem resize max'

Best Regards
Wang Yugui (wangyugui@e16-tech.com)
2022/01/27

> 
> Best Regards
> Wang Yugui (wangyugui@e16-tech.com)
> 2022/01/27
> 
> > I don't have a bpftrace setup and sadly i cant do much debugging on this machine.
> > 
> > However i am sure its systemd that is involved in it. The few lines before the crash read:
> > 
> > Ιαν 26 22:45:06 mainland systemd[1]: Stopped WPA supplicant.
> > Ιαν 26 22:45:06 mainland systemd-homework[14696]: Discovered used LUKS device /dev/mapper/home-toliz, and validated password.
> > Ιαν 26 22:45:07 mainland systemd-homework[14696]: Successfully re-activated LUKS device.
> > Ιαν 26 22:45:07 mainland systemd-homework[14696]: Discovered used loopback device /dev/loop0.
> > Ιαν 26 22:45:07 mainland systemd-homework[14696]: offset = 1048576, size = 137436856320, image = 137438953472
> > Ιαν 26 22:45:07 mainland systemd-homework[14696]: Ready to resize image size 128.0G → 1.8G, partition size 127.9G → 1.8G, file system size 127.9G → 1.7G.
> > Ιαν 26 22:45:07 mainland systemd-homework[14696]: Allocated additional 124.8G.
> > Ιαν 26 22:45:07 mainland kernel: BTRFS info (device dm-0): relocating block group 2177892352 flags data
> > Ιαν 26 22:45:07 mainland kernel: BTRFS info (device dm-0): relocating block group 1104150528 flags data
> > Ιαν 26 22:45:08 mainland systemd-homework[14696]: Failed to resize file system: Read-only file system
> > Ιαν 26 22:45:08 mainland kernel: BTRFS info (device dm-0): relocating block group 30408704 flags metadata|dup
> > 
> > On 27/1/22 01:19, Boris Burkov wrote:
> > > On Thu, Jan 27, 2022 at 12:07:53AM +0200, Apostolos B. wrote:
> > >>  ?This is what homectl inspect user reports:
> > >>
> > >>  ? Disk Size: 128.0G
> > >>  ? Disk Usage: 3.8G (= 3.1%)
> > >>  ? Disk Free: 124.0G (= 96.9%)
>