lsof and open files from the nfs-server

lsof and open files from the nfs-server

[Jesper Krogh]

Hi.

Quite often when you have to umount a fileshare you get the
message "Device or resource busy". Typically I traverse through
the output of lsof | grep mountpoint and stop processes or kill
until I can safely umount.

But the nfs-kernel-server does not register its open files, so
seen from userspace is it extremely hard to find out that is actually
is the nfs-server that prevents you from being able to umount
the filesystems.

Would it be possible to register the open files the same place
so administrators can see them?

... basically just a feature-request from one who just spend an hour on 
that.

-- 
Jesper

Re: lsof and open files from the nfs-server

[Boaz Harrosh]

On 10/13/2010 11:11 PM, Jesper Krogh wrote:
> Hi.
> 
> Quite often when you have to umount a fileshare you get the
> message "Device or resource busy". Typically I traverse through
> the output of lsof | grep mountpoint and stop processes or kill
> until I can safely umount.
> 
> But the nfs-kernel-server does not register its open files, so
> seen from userspace is it extremely hard to find out that is actually
> is the nfs-server that prevents you from being able to umount
> the filesystems.
> 
> Would it be possible to register the open files the same place
> so administrators can see them?
> 
> ... basically just a feature-request from one who just spend an hour on 
> that.
> 

Me to!

Also note that even if there are no open files in clients
and no client mounts on the server, but there where in the
passed. The used to be used super-block is referenced. Only
restart of the nfs service will release it.

But yes if it could register as a special file for lsof to
see it would help a lot.

Boaz
 

Re: lsof and open files from the nfs-server

[J. Bruce Fields]

On Mon, Oct 18, 2010 at 06:25:12PM +0200, Boaz Harrosh wrote:
> On 10/13/2010 11:11 PM, Jesper Krogh wrote:
> > Hi.
> > 
> > Quite often when you have to umount a fileshare you get the
> > message "Device or resource busy". Typically I traverse through
> > the output of lsof | grep mountpoint and stop processes or kill
> > until I can safely umount.
> > 
> > But the nfs-kernel-server does not register its open files, so
> > seen from userspace is it extremely hard to find out that is actually
> > is the nfs-server that prevents you from being able to umount
> > the filesystems.
> > 
> > Would it be possible to register the open files the same place
> > so administrators can see them?
> > 
> > ... basically just a feature-request from one who just spend an hour on 
> > that.
> > 
> 
> Me to!
> 
> Also note that even if there are no open files in clients
> and no client mounts on the server, but there where in the
> passed. The used to be used super-block is referenced. Only
> restart of the nfs service will release it.
> 
> But yes if it could register as a special file for lsof to
> see it would help a lot.

So what does lsof do, scan /proc/?  Does it make sense to have proc
entries for kernel threads?  Is there any other subsystem that does this
kind of thing?

--b.

Re: lsof and open files from the nfs-server

[Boaz Harrosh]

On 10/18/2010 07:04 PM, J. Bruce Fields wrote:
> On Mon, Oct 18, 2010 at 06:25:12PM +0200, Boaz Harrosh wrote:
>> On 10/13/2010 11:11 PM, Jesper Krogh wrote:
>>> Hi.
>>>
>>> Quite often when you have to umount a fileshare you get the
>>> message "Device or resource busy". Typically I traverse through
>>> the output of lsof | grep mountpoint and stop processes or kill
>>> until I can safely umount.
>>>
>>> But the nfs-kernel-server does not register its open files, so
>>> seen from userspace is it extremely hard to find out that is actually
>>> is the nfs-server that prevents you from being able to umount
>>> the filesystems.
>>>
>>> Would it be possible to register the open files the same place
>>> so administrators can see them?
>>>
>>> ... basically just a feature-request from one who just spend an hour on 
>>> that.
>>>
>>
>> Me to!
>>
>> Also note that even if there are no open files in clients
>> and no client mounts on the server, but there where in the
>> passed. The used to be used super-block is referenced. Only
>> restart of the nfs service will release it.
>>
>> But yes if it could register as a special file for lsof to
>> see it would help a lot.
> 
> So what does lsof do, scan /proc/?  Does it make sense to have proc
> entries for kernel threads?  Is there any other subsystem that does this
> kind of thing?
> 

Don't mind if I do ;-)

I don't know about policy here and what it actually means (Lifetime rules,
module dependency, ...) But it would be nice to have it, as a user.

If it can not be added to the regular /proc places. Maybe we can patch
lsof to also look in nfs special places and print those as well.

> --b.

Thanks
Boaz