Re: [NFS] question about file identifier in NFS trace data

[Xue Peng Li <xuepengl at cn dot ibm dot com>]

Thanks.

Best Regards,

Li Xuepeng  (李雪鹏)

Linux Performance, China Systems & Technology Lab
China Development Labs, Beijing
Email: xuepengl@cn.ibm.com

systemtap-owner@sourceware.org wrote on 2006-08-29 11:58:15:

> On Tue, 2006-08-29 at 11:12 +0800, Xue Peng Li wrote:
> > Hi,
> >     I am now working on NFS trace hooks of LKET. I want to know what 
file 
> > is being operated for both client side and server 
> > side NFS functions. On client side, two kinds of data can be used to 
> > identify files, i.e. i_ino field of the inode object
> > which can identify the filesystem inode on disk, and the other is NFS 
file 
> > handler which is used to identify files between 
> > client and server.On server side ,only NFS file handler received from 
> > client can be used to identify file(It's very 
> > complicated to convert it to inode object at nfsd_* probe point).
> > 
> >     I am not sure which one should be traced. If file handler is 
traced 
> > ,there is another problem , the total length of
> > file handler is 128 bytes,and for NFSV3 the length is variable. I am 
not 
> > sure how many bytes should be traced, if 128 bytes
> > are traced ,it's will so long for performance penalty, usually we only 

> > trace serval bytes for one data.
> > 
> >    Could anyone give me some suggestions? Thanks in advance
> 
> See what we use for dprintk(): use dentries whenever possible, else use
which filed of dentries should be traced , i_ino and file name?
> the combination sb->s_id + fileid.
do you think the combination can identify the file between server and 
client?
On server side , nfsd_proc function only receives file handler as its 
input arguments ,
how can I extract the s_id and fileid from file handler , because at 
nfsd_proc probe
point ,I can't call fh_verify to convert file handler to inode . Do you 
think it's 
possible to extract such information from file handler according to 
comments in
include/linux/nfsd/nfsfh.h
> 
> Cheers,
>   Trond
>