Re: 5.5-5.6-rc1, fstrim reports different value 1 minute later

[Chris Murphy <lists@colorremedies.com>]

On Wed, Feb 12, 2020 at 11:21 PM Roman Mamedov <rm@romanrm.net> wrote:
>
> On Wed, 12 Feb 2020 23:08:03 -0700
> Chris Murphy <lists@colorremedies.com> wrote:
>
> > Host: kernel 5.5.3, qemu-kvm, Btrfs, backing file is raw with +C  5.6.
> > Guest: kernel 5.6.0-rc1, / is Btrfs
> >
> > Boot and login, and immediately run these commands:
> >
> > [root@localhost ~]# df -h
> > /dev/vda4        96G  4.4G   91G   5% /
> > # fstrim -v /
> > /: 91 GiB (97633062912 bytes) trimmed
> >
> > 1 minute later
> >
> > [root@localhost ~]# fstrim -v /
> > /: 3.5 GiB (3747549184 bytes) trimmed
> > [root@localhost ~]#

Reboot the VM with 5.5.3 and I get very slightly different values but
same behavior.
~]$ sudo -i
[sudo] password for hack:
[root@localhost ~]# fstrim -v /
/: 92.2 GiB (98953457664 bytes) trimmed
[root@localhost ~]# fstrim -v /
/: 3.7 GiB (3950542848 bytes) trimmed
[root@localhost ~]# exit

5 minutes later

$ sudo fstrim -v /
/: 3.4 GiB (3658797056 bytes) trimmed


> For completeness, what would be returned the 3rd time you trim?

I'm not seeing a pattern. Sometimes it's the same. Sometimes it's a
little different like above.

-- 
Chris Murphy