[systemd-devel] PATCH: do not run fsck on tmpfs mountpoint

[Karel Zak]

On Wed, Nov 02, 2011 at 03:39:37PM +0100, Kay Sievers wrote:
> On Wed, Nov 2, 2011 at 15:27, Karel Zak <kzak at redhat.com> wrote:
> > On Wed, Nov 02, 2011 at 12:15:29PM +0100, Kay Sievers wrote:
> >> On Wed, Nov 2, 2011 at 11:21, Frederic Crozat <fcrozat at suse.com> wrote:
> >> > Le mardi 01 novembre 2011 à 16:54 +0100, Lennart Poettering a écrit :
> >> >> On Thu, 27.10.11 16:19, Frederic Crozat (fcrozat at suse.com) wrote:
> >> >>
> >> >> > You really don't want to fsck a tmpfs, even if passno is non-null (it
> >> >> > was causing many issue, forcing system to go to emergency).
> >> >>
> >> >> Hmm, I wonder if this is the right fix. I wonder what fsck -a does if it
> >> >> finds a passno != 0 for an entry where /sbin/fsck.xxx. If that fails on
> >> >> it we should probably do so too. If it silently ignores passno != 0
> >> >> where the fsck is missing then we probably should implement a similar
> >> >> logic. However doing an explicit check for tmpfs sounds wrong to me:
> >> >> there are other fs where fsck makes little sense, and we would have to
> >> >> either check them all or none?
> >> >
> >> > I've just checked fsck code :
> >> > - it has a list of "ignore" filesystems :
> >>
> >> Please let's not start copying that stuff, fsck is hardly an example
> >> how things should be done today. Such lists can never be up-to-date,
> >> and they are not today.
> >>
> >> I guess, if such broken configs should be supported, which I'm really
> >> not sure about, fsck itself should be made to find that out and return
> >> successful without doing anything. Such things should not be guarded
> >> in systemd with just another static blacklist.
> >>
> >> Not sure if there are valid use cases, maybe we are able to skip all
> >> mounts which are not backed by a device, where major(s.st_rdev) == 0?
> >
> >  Unfortunately major(s.st_rdev) is probably useless, try to mount any
> >  btrfs device :-)
> 
> Yeah, it was about fsck only, not mount. :)

 Hmm... I'm talking about fsck, try to mount btrfs and check major(st.st_dev)
 for the mountpoint.

> >  BTW, in systemd/src/fsck.c I see:
> >
> >        /* Virtual root devices don't need an fsck */
> >        if (major(st.st_dev) == 0)
> >              return 0;
> >
> >  it means that btrfs root will be interpreted as a virtual device :-)
> 
> Oh, why do we run into the issues with tmpfs then?

 This code is used for system root ("/").

    Karel

-- 
 Karel Zak  <kzak at redhat.com>
 http://karelzak.blogspot.com