FreeBSD NFS client goes into infinite retry loop
korvus at comcast.net
Mon Mar 22 14:52:46 UTC 2010
On 3/19/2010 11:27 PM, Rick Macklem wrote:
> On Fri, 19 Mar 2010, Steve Polyack wrote:
> [good stuff snipped]
>> This makes sense. According to wireshark, the server is indeed
>> transmitting "Status: NFS3ERR_IO (5)". Perhaps this should be STALE
>> instead; it sounds more correct than marking it a general IO error.
>> Also, the NFS server is serving its share off of a ZFS filesystem, if
>> it makes any difference. I suppose ZFS could be talking to the NFS
>> server threads with some mismatched language, but I doubt it.
> Ok, now I think we're making progress. If VFS_FHTOVP() doesn't return
> ESTALE when the file no longer exists, the NFS server returns whatever
> error it has returned.
> So, either VFS_FHTOVP() succeeds after the file has been deleted, which
> would be a problem that needs to be fixed within ZFS
> ZFS returns an error other than ESTALE when it doesn't exist.
> Try the following patch on the server (which just makes any error
> returned by VFS_FHTOVP() into ESTALE) and see if that helps.
> --- nfsserver/nfs_srvsubs.c.sav 2010-03-19 22:06:43.000000000 -0400
> +++ nfsserver/nfs_srvsubs.c 2010-03-19 22:07:22.000000000 -0400
> @@ -1127,6 +1127,8 @@
> error = VFS_FHTOVP(mp, &fhp->fh_fid, vpp);
> + if (error != 0)
> + error = ESTALE;
> if (error)
> goto out;
> Please let me know if the patch helps, rick
The patch seems to fix the bad behavior. Running with the patch, I see
the following output from my patch (return code of nfs_doio from within
nfssvc_iod: iod 0 nfs_doio returned errno: 70
Furthermore, when inspecting the transaction with Wireshark, after
deleting the file on the NFS server it looks like there is only a single
error. This time there it is a reply to a V3 Lookup call that contains
a status of "NFS3ERR_NOENT (2)" coming from the NFS server. The client
also does not repeatedly try to complete the failed request.
Any suggestions on the next step here? Based on what you said it looks
like ZFS is falsely reporting an IO error to VFS instead of ESTALE /
NOENT. I tried looking around zfs_fhtovp() and only saw returns of
EINVAL, but I'm not even sure I'm looking in the right place.
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