Date: Mon, 22 Mar 2010 12:44:04 -0400 From: Steve Polyack <korvus@comcast.net> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-fs@freebsd.org, User Questions <freebsd-questions@freebsd.org>, bseklecki@noc.cfi.pgh.pa.us Subject: Re: FreeBSD NFS client goes into infinite retry loop Message-ID: <4BA79E54.5030504@comcast.net> In-Reply-To: <201003221200.41607.jhb@freebsd.org> References: <4BA3613F.4070606@comcast.net> <4BA78444.4040707@comcast.net> <4BA7911F.5060905@comcast.net> <201003221200.41607.jhb@freebsd.org>
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On 03/22/10 12:00, John Baldwin wrote:
> 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.
>
>
It looks like it also returns ESTALE when the inode is invalid (<
ROOTINO || > max inodes?) - would an unlinked file in FFS referenced at
a later time report an invalid inode?
But back to your point, zfs_zget() seems to be failing and returning the
EINVAL before zfs_fhtovp() even has a chance to set and check zp_gen.
I'm trying to get some more details through the use of gratuitous
dprintf()'s, but they don't seem to be making it to any logs or the
console even with vfs.zfs.debug=1 set. Any pointers on how to get these
dprintf() calls working?
Thanks again.
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