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

[Alex Bligh <alex@alex.org.uk>]

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Neil,

On 18/06/2014 07:27, NeilBrown wrote:
> 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.

I don't *think* I saw the same issue without fsid=0, but I might be
wrong.

>> 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?

No, umount /mnt gives the same error.

> 
> 
>> 
>> 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
> 


- -- 
Alex Bligh
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