helpdavfs2 - Support: sr #108850, mounting via systemd fails

 
 

sr #108850: mounting via systemd fails

Submitted by:  None
Submitted on:  Tue Jul 21 09:34:55 2015  
 
Category: NonePriority: 5 - Normal
Severity: 3 - NormalStatus: Done
Privacy: PublicAssigned to: Werner Baumann <wbaumann>
Originator Email: -unavailable-Open/Closed: Open
Operating System: GNU/Linux

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Sat Jul 25 10:24:08 2015, comment #1:

I tested on my Debian 8 system (amd64) and it is a bit confusing.

  • without mount option "_netdev": systemd tries to mount the davfs2 file system after the root file system has been remounted r/w. It calls mount with option -n and mounting fails. I'm not sure why it sets option -n, probably because /etc/mtab is a symbolic link to /proc/mounts.
  • with mount option "_netdev" set in fstab it will still first try to mount the davfs2 file system with option -n and before the network is up. So it fails again. But later it will retry after the netork is running and without option -n and mounting succeeds.

So setting mount option _netdev in fstab should help.

More info about the problem:

  • davfs2 should recognize option -n (and other generic options). But I'm not sure how it should behave.
  • davfs2 needs an entry in /etc/mtab or /var/run/mount/utab (a hardly documented new feature of mount). Without this entry the umount program will not be able to call the davfs2 umount helper. This helper is necessary to make sure that umount only returns after davfs2 has synchronized the cache or at least saved all necessary information to recover the state of the cache when mounted again.
  • davfs2 also needs write access to the cache directory. The default when mounted by systemd is /vare/cache/davfs2. So a davfs2 file system can not be mounted when /var/cache is read only.
  • davfs2 needs network connection.

Summary: a davfs2 file system must only be mounted after the root file system is mounted read/write and the network is working. If /etc/mtab is a symbolic link to /proc/mounts davfs2 will use /var/run/mount/utab, just like mount.

I will create a bug report for not recognizing the -n option, but I'm not yet sure how to treat it.

Werner

Werner Baumann <wbaumann>
Project AdministratorIn charge of this item.
Tue Jul 21 09:34:55 2015, original submission:

Hello

systemd uses "-n" mount option. This is not understood by davfs and mounting fails.

Please see this issue, where I reported before:

https://github.com/systemd/systemd/issues/507

Thanks

Anonymous

 

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    Follow 3 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Wed May 18 18:23:09 2016wbaumannStatusIn Progress=>Done
    Sat Jul 25 10:24:08 2015wbaumannStatusNone=>In Progress
      Assigned toNone=>wbaumann

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