Re: [PATCH] fstrim: add systemd units

[Ruediger Meier <sweet_f_a@gmx.de>]

On Thursday 10 April 2014, Ruediger Meier wrote:
> On Thursday 10 April 2014, Karel Zak wrote:
> > On Thu, Apr 10, 2014 at 11:17:04AM +0200, Ruediger Meier wrote:
> > > Thanks, maybe we could add another minor change to "fstrim -a"
> > > itself. If possible it would be IMO useful to skip bind mounts to
> > > avoid trimming the same filesystem several times in a row like
> > > this:
> > >
> > > $ grep "tmp" /etc/fstab
> > > /dev/vg0/tmpdirs     /mnt/tmpdirs   ext4       acl,user_xattr    
> > > 1 2 /mnt/tmpdirs/tmp     /tmp           none       bind
> > > 0 0 /mnt/tmpdirs/var/tmp /var/tmp       none       bind
> > >   0 0
> > >
> > > $ ./fstrim -av
> > > /tmp: 392 KiB (401408 bytes) trimmed
> > > /var/tmp: 0 B (0 bytes) trimmed
> > > /mnt/tmpdirs: 0 B (0 bytes) trimmed
> > >
> > > Skipping bind mounts should still trim all mounted filesytems.
> >
> > Good idea point, but what about systems where the original
> > mountpoint is umounted?
> >
> >  /dev/sda1  /foo    ext4    default
> >  /foo       /bar    none    bind
> >
> >   # mount /foo
> >   # mount /bar
> >   # umount /foo
>
> Nice, I thought that wouldn't be even possible to do.
>
> > the another story is that we use /proc/self/mountinfo where is
> > nothing about "bind". It would be probably better to de-duplicate
> > the list of the filesystems according to filesystem UUID or so.
> >
> > I'll think about it.
>
> Maybe you could borrow the filter from lsblk. With my fstab above it
> seems to skip the bind mounts:
>
> NAME            MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
> sda               8:0    0 232.9G  0 disk
> sda1            8:1    0   512M  0 part /boot
> sda2            8:2    0 232.4G  0 part
>   vg0-root    253:0    0    24G  0 lvm  /
>   vg0-swap    253:1    0     4G  0 lvm  [SWAP]
>   vg0-tmpdirs 253:2    0 204.4G  0 lvm  /mnt/tmpdirs

... seems the first mount wins. After umounting the origin:

$ umount /mnt/tmpdirs/
$ lsblk
NAME            MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda               8:0    0 232.9G  0 disk
├─sda1            8:1    0   512M  0 part /boot
└─sda2            8:2    0 232.4G  0 part
  ├─vg0-root    253:0    0    24G  0 lvm  /
  ├─vg0-swap    253:1    0     4G  0 lvm  [SWAP]
  └─vg0-tmpdirs 253:2    0 204.4G  0 lvm  /tmp
sr0              11:0    1  1024M  0 rom
loop0             7:0    0     1G  0 loop /mnt/a

cu,
Rudi