On Wed, 2012-09-05 at 14:40 +0200, Diego Moreno wrote:
> Hello everyone,
>
> Performing some attribute caching tests I think I found some
> inconsistencies between nfsv3 and nfsv4. Running a kernel based on
> rhel6.3 (2.6.32-279.el6.x86_64) I found nfsv4 doesn't manage a file
> modified on the server side (even with the noac mount option) while
> nfsv3 does.
>
> My test will be modifying a file every second on the server mount point:
>
> [root@nfs ~]# FILE=/tmp/nfs_server/myfile ; while true ; do sleep 1 ;
> sed -i 's/text1/text2/g' $FILE ; cat $FILE ; sleep 1; sed -i
> 's/text2/text1/g' $FILE ; cat $FILE ; done
> text2
> text1
> text2
> text1
> text2
> (and so on...)
>
> Meanwhile, the client (which BTW is the same machine) will read the file
> every second :
>
> With NFSv4:
>
> [root@nfs ~]# mount -o noac,vers=4 nfs:/tmp/nfs_server/ /tmp/nfs_client/
> [root@nfs ~]# for i in 1 2 3 4 5 ; do cat /tmp/nfs_client/myfile; sleep
> 1 ; done
> text2
> text1
> text1
> text1
> text1
>
> With NFSv3:
> [root@nfs ~]# mount -o noac,vers=3 nfs:/tmp/nfs_server/ /tmp/nfs_client/
> [root@nfs ~]# for i in 1 2 3 4 5 ; do cat /tmp/nfs_client/myfile; sleep
> 1 ; done
> text1
> text2
> text1
> text2
> text1
>
> I can see in the tcpdump traces how the new change attribute and the
> FATTR4_TIME_MODIFY attributes are well received but it's as if the nfs
> client were ignoring these changes. I've been searching in the NFS list
> but I didn't find anything similar. Is this a bug or just a normal
> behavior? Sorry if it has been already pointed out.
]If you can reproduce the same issues on the upstream kernel, then it is
on topic for this list, otherwise it is a question for Red Hat.
Cheers
Trond
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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