Re: Ways to Monitor NFS Calls from Client

[Lee Eric <openlinuxsource at gmail dot com>]

Hi David,

Thanks for your information and I just gave a try on nfs.proc.open
which is working fine. However, I have some questions about the return
values.

from the tapset manual nfs.proc.open has 6 return values so how do I
know the types of those return values? For instance, how do I look up
the return value type of prot?

Thanks.

Hui

On Mon, Aug 22, 2016 at 7:43 AM, David Smith <dsmith@redhat.com> wrote:
> On 08/22/2016 02:40 AM, Lee Eric wrote:
>> Hi,
>>
>> I'm not sure if this topic had been raised previously. I am exploring
>> some ways to monitor NFS calls from client side. So I checked
>> https://sourceware.org/systemtap/examples/io/nfs_func_users.stp and
>> https://sourceware.org/systemtap/tapsets/nfsd.stp.html. However, that
>> makes me confused that because both does not work(or maybe the way I'm
>> using is wrong).
>>
>> For the first one there's no output when client access files on NFS
>> server. For the second one I wrote a very small and simple stp:
>>
>> probe nfs.proc.open {
>>     printf("Opening file %s from server %x\n", filename, server_ip)
>> }
>>
>> Still, if I access any files there's no output either.
>>
>> So I'm curious is there any actual way to capture NFS calls from
>> client side via SystemTap? Also, for the second method, any way to get
>> other NFS calls like GETATTR, READDIRPLUS etc.?
>
> Systemtap can monitor nfs client and nfs server activity.
>
> The nfsd.stp tapset is for NFS server monitoring. Any script using the
> nfsd.stp tapset must be run on the NFS server system. A script using the
> nfsd.stp tapset will see NFS activity from all NFS client systems.
>
> The nfs_proc.stp tapset is for NFS client monitoring. Any script using
> the nfs_proc.stp tapset must be run on the particular NFS client system.
> Note that a script using nfs_proc.stp to do client side NFS monitoring
> will only be able to monitor NFS activity on that particular client
> system. It won't see any NFS activity from different client systems.
>
> Since you'd like to monitor NFS calls from a NFS client, you'd want to
> use the nfs_proc.stp tapset. Here's an example run from one of my
> systems that is an NFS client. In the following example, the file
> 'ChangeLog' is stored on an NFS partition:
>
> ====
> # stap -e 'probe nfs.proc.open { printf("%s(%s)\n", name, argstr) }' -c
> 'cat ChangeLog > /dev/null'
> nfs.proc.open(ChangeLog,32768,32797)
> ====
>
> If something similar doesn't work for you, we'll have to dig deeper into
> your setup.
>
> As far as GETATTR and READDIRPLUS goes, it appears that the nfs_proc.stp
> tapset doesn't have probes for those calls. However, it would be fairly
> easy to add your own.
>
> --
> David Smith
> dsmith@redhat.com
> Red Hat
> http://www.redhat.com
> 256.217.0141 (direct)
> 256.837.0057 (fax)