Date: Mon, 22 Mar 2010 12:00:41 -0400 From: John Baldwin <jhb@freebsd.org> To: Steve Polyack <korvus@comcast.net> Cc: freebsd-fs@freebsd.org, Rick Macklem <rmacklem@uoguelph.ca>, User Questions <freebsd-questions@freebsd.org>, bseklecki@noc.cfi.pgh.pa.us Subject: Re: FreeBSD NFS client goes into infinite retry loop Message-ID: <201003221200.41607.jhb@freebsd.org> In-Reply-To: <4BA7911F.5060905@comcast.net> References: <4BA3613F.4070606@comcast.net> <4BA78444.4040707@comcast.net> <4BA7911F.5060905@comcast.net>
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On Monday 22 March 2010 11:47:43 am Steve Polyack wrote:
> On 03/22/10 10:52, Steve Polyack wrote:
> > 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
> >> OR
> >> 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;
> >> vfs_unbusy(mp);
> >> 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 nfsiod):
> > 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.
>
> Further on down the rabbit hole... here's the piece in zfs_fhtovp()
> where it's kicking out EINVAL instead of ESTALE - the following patch
> corrects the behavior, but of course also suggests further digging
> within the zfs_zget() function to ensure that _it_ is returning the
> correct thing and whether or not it needs to be handled there or within
> zfs_fhtovp().
>
> ---
> src-orig/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
> 2010-03-22 11:41:21.000000000 -0400
> +++ src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
> 2010-03-22 16:25:21.000000000 -0400
> @@ -1246,7 +1246,7 @@
> dprintf("getting %llu [%u mask %llx]\n", object, fid_gen, gen_mask);
> if (err = zfs_zget(zfsvfs, object, &zp)) {
> ZFS_EXIT(zfsvfs);
> - return (err);
> + return (ESTALE);
> }
> zp_gen = zp->z_phys->zp_gen & gen_mask;
> if (zp_gen == 0)
So the odd thing here is that ffs_fhtovp() doesn't return ESTALE if VFS_VGET()
(which calls ffs_vget()) fails, it only returns ESTALE if the generation count
doesn't matter.
--
John Baldwin
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