Re: Cannot mount DFS shares after upgrade to 10.9
Hi,
On Mon, Apr 05, 2021 at 07:35:45PM +0200, Salvatore Bonaccorso wrote:
> Hi,
>
> On Sat, Apr 03, 2021 at 06:32:50PM +0000, Joel Davies wrote:
> > We have some autofs mounts that stopped working after the 10.9
> > updates were applied. Seems that the kernel update is the cause - I
> > applied just the kernel update and same thing happens. The mounts
> > that stopped working were targeting Windows domain DFS shares. The
> > DFS root can still be mounted (//domain.local/DFS) which we may have
> > to end up using but then will have to reconfigure stuff. Subfolders
> > of normal shares also can still be mounted
> > (//Server.domain.local/Share/Subfolder). It is just the DFS shares
> > that don't work currently (//domain.local/DFS/Share).
> >
> > Here is what happens mounting the shares manually:
> >
> > Under kernel 4.19.0-14-amd64 (previous to 10.9 updates):
> >
> > $sudo mount -t cifs -o username=user,vers=3.0 //domain.local/DFS/Share /mnt --verbose
> > Password for user@//domain.local/DFS/Share: *********
> > mount.cifs kernel mount options: ip=10.x.x.x,unc=\\domain.local\DFS,vers=3.0,user=user,prefixpath=Share,pass=********
> >
> > Normally no messages in syslog and share is successfully mounted.
> >
> > After updating kernel to 4.19.0-16-amd64:
> >
> > $sudo mount -t cifs -o username=user, //domain.local/DFS/Share /mnt --verbose
> > Password for user@//domain.local/DFS/Share: *********
> > mount.cifs kernel mount options: ip=10.x.x.x,unc=\\domain.local\DFS,vers=3.0,user=user,prefixpath=Share,pass=********
> > mount error(2): No such file or directory
> > Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)
> >
> > Syslog shows:
> > CIFS VFS: cifs_read_super: get root inode failed
> >
> > I didn't find much of use online to troubleshoot that message. I did
> > try different values of vers option as well as each of serverino and
> > noserverino and several combinations of both - no difference. Any
> > suggestions?
> >
> > (Occasionally syslog also shows "CIFS VFS: error -2 on ioctl to get
> > interface list". This happened about one in five mount attempts both
> > before and after the kernel update, regardless of whether or not the
> > share mounted. Since it did appear before the update when mounting
> > always worked, I am assuming it is not relevant.)
>
> This is probably a regression between 4.19.171 and 4.19.181.
>
> There were cifs related changes. a738c93fb1c1 ("cifs: Set
> CIFS_MOUNT_USE_PREFIX_PATH flag on setting cifs_sb->prepath.") might
> be a candidate.
>
> Can you please report a bug against the kernel?
>
> If you can test a build, please do test with that commit reverted and
> see if the issue disappers.
More precisely I think to be able to reproduce the behaviour with
4.19.181-1 but not with 4.19.177-1.
Regards,
Salvatore
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