Re: Peculiarity in handling NFSv4 mount paths with fsid=0

[NeilBrown <neilb@suse.de>]

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On Sat, 14 Jun 2014 10:37:14 +0100 Alex Bligh <alex@alex.org.uk> wrote:

> I've discovered I think a peculiarity with handling mount paths with fsid=0.

It looks to me like this has nothing to do with "fsid=0" and everything to do
with using the expected number of '/' characters.


> This is on Ubuntu Precise (old) but I've used 3.13 too with the same
> problem.
> 
> I have an exports line like this:
> /storage/local 
> *(rw,sync,wdelay,nohide,crossmnt,insecure,no_root_squash,no_all_squash,no_subtree_check,secure_locks,acl,fsid=0,anonuid=65534,anongid=65534)
> 
> 
> And mounted a directory like this (which succeeded)
> 
> # mount -t nfs4 10.157.208.1:nfs-01 /mnt
> 
> And unmount did this:
> 
> # umount 10.157.208.1:nfs-01
> /mnt was not found in /proc/mounts
> /mnt was not found in /proc/mounts
> 
> Examination showed /proc/mounts contained the line:
> 
> 10.157.208.1:/nfs-01 /mnt nfs4 
> rw,relatime,vers=4.0,rsize=262144,wsize=262144,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=10.157.208.1,local_lock=none,addr=10.157.208.1 
> 0 0
> 
> Whereas the outptut of 'mount' contained the line:
> 
> 10.157.208.1:nfs-01 on /mnt type nfs4 
> (rw,addr=10.157.208.1,clientaddr=10.157.208.1)
> 
> There is a difference here between "/nfs-01" and "nfs-01".
> 
> This might merely be an annoying bug, where it not for the fact that as
> far as I can tell the mount is now cannot be unmounted with userspace
> tools. No amount of --fake and -n appears to help. System reset required.

Doesn't
   umount /mnt
work?


> 
> Of course had I typed:
> 
> # mount -t nfs4 10.157.208.1:/nfs-01 /mnt
> 
> all would have been well.
> 
> I suspect something should be canonicalising the path consistently.
> 

I agree there.

NeilBrown


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