Re: unable to mount nfs4 mount

[NeilBrown <neilb@suse.com>]

[-- Attachment #1: Type: text/plain, Size: 4765 bytes --]

On Fri, Jan 06 2017, daggs wrote:

> Greetings,
>
>> Subject: Re: unable to mount nfs4 mount
>>
>> On Tue, Dec 27 2016, daggs wrote:
>> 
>> > Greetings Neil,
>> >
>> >> On Mon, Dec 26 2016, daggs wrote:
>> >> 
>> >> > Greetings,
>> >> >
>> >> >> On Mon, Dec 26 2016, daggs wrote:
>> >> >> 
>> >> >> >> Can you strace mountd while you attempt a mount?
>> >> >> >> e.g.
>> >> >> >>   strace -o /tmp/trace -s 1000 -p 241
>> >> >> >> 
>> >> >> >> and send the /tmp/trace.
>> >> >> >> Also, after the attempt fails, run
>> >> >> >>  rpcdebug -m rpc -s cache
>> >> >> >>  grep . /proc/net/rpc/*/c*
>> >> >> >>  cat /proc/fs/nfsd/exports
>> >> >> >> 
>> >> >> >> and report the output.
>> >> >> >> 
>> >> >> > here:
>> >> >> >
>> >> >> > # cat /tmp/trace
>> >> >> > pselect6(1024, [3 4 5 7 8 9 10 11 12], NULL, NULL, NULL, NULL) = 1 (in [3])
>> >> >> > read(3, "nfsd 10.0.0.1\n", 32768)       = 14
>> >> >> > openat(AT_FDCWD, "/run/nfs/etab", O_RDONLY) = 14
>> >> >> > fstat(14, {st_mode=S_IFREG|0644, st_size=435, ...}) = 0
>> >> >> > close(14)                               = 0
>> >> >> > write(3, "nfsd 10.0.0.1 2079 10.0.0.0/24 \n", 32) = 32
>> >> >> 
>> >> >> This is weird.
>> >> >> Here mountd is telling nfsd that when a request comes from IP address
>> >> >> 10.0.0.1, it should look for export entries associated with the client
>> >> >> name "10.0.0.0/24", which is good.
>> >> >> However the expiry time for that information is "2079", which is back in
>> >> >> January 1970.
>> >> >> When mountd writes that number, it computes it as
>> >> >>    time(0) + DEFAULT_TTL
>> >> >> where DEFAULT_TTL is (30 * 60)
>> >> >> Which suggests time(0) is "279".
>> >> >> 
>> >> >> What is the current time on this system?
>> >> >> 
>> >> >> If it really was very early on Jan 1st 1970, it should work, however...
>> >> >> 
>> >> >> 
>> >> >> > pselect6(1024, [3 4 5 7 8 9 10 11 12], NULL, NULL, NULL, NULL <detached ...>
>> >> >> > # rpcdebug -m rpc -s cache
>> >> >> > rpc        cache
>> >> >> > # grep . /proc/net/rpc/*/c*
>> >> >> > /proc/net/rpc/auth.unix.gid/content:#uid cnt: gids...
>> >> >> > /proc/net/rpc/auth.unix.ip/channel:nfsd 10.0.0.1
>> >> >> > /proc/net/rpc/auth.unix.ip/channel:nfsd 10.0.0.1
>> >> >> > /proc/net/rpc/auth.unix.ip/content:#class IP domain
>> >> >> > /proc/net/rpc/auth.unix.ip/content:# expiry=2079 refcnt=1 flags=1
>> >> >> > /proc/net/rpc/auth.unix.ip/content:# nfsd 10.0.0.1 10.0.0.0/24
>> >> >> 
>> >> >> ...the fact that this line is commented out indicates that the entry in
>> >> >> the cache is already expired.  So the time must be after 2079.
>> >> >> 
>> >> >> Maybe the time is getting set from the network at an awkward time that
>> >> >> races with NFS service some how.
>> >> >> Can you find a way to run "exportfs -f" after the time has been set
>> >> >> correctly?
>> >> >> 
>> >> >> NeilBrown
>> >> >> 
>> >> >> 
>> >> >
>> >> > wait, I think I've seen this somewhere, does this feature needs rtc? this board doesn't have rtc component.
>> >> > for example, I cannot use openssh as ssh server because it needs rtc. I have to use dropbear.
>> >> > if so, this looks like it will affect nfsv3 mounts, am I right?
>> >> 
>> >> No, you shouldn't need an RTC.
>> >> You need the synchronize the clock with ntp or similar, else time stamps
>> >> on files will look wrong.
>> >> Though I think we fixed issues with wall-clock-time jumping in 2.6.37...
>> >> 
>> >> If you could try using "exportfs -f", and explain what does happen with
>> >> time - do you use ntp ?? - we might be able to make progress.
>> >
>> > I'll build ntp into the image and try. does this affects nfsv3 too?
>> 
>> Having correct time is quite important for any version of NFS.  With out
>> it, time stamps on files get confused.  "make" doesn't cope at all,
>> "tar" often complains, other tools might experience other problems.
>> 
>> I still cannot quite see why having an incorrect clock would cause the
>> particular symptoms you are experiencing, but it is worth fixing anyway.
> I worked around the issue by setting the date manually. the issue still presists.
>
>> 
>> >
>> > what should I do with the "exportfs -f"? jsut run it and retry?
>> 
>> Yes.
> exportfs -f didn't made any difference.

OK. Please:
 - make sure the time is (nearly) correct - e.g. running date manually.
 - run "exportfs -f"
 - run "strace" on mountd
 - try to mount the filesystem
 - stop the strace
 - run
      rpcdebug -m rpc -s cache
      grep . /proc/net/rpc/*/*
      cat /proc/fs/nfsd/exports

  (note that it isn't quite the same 'grep' as before).

then post the output of the 'strace', the 'grep', and the 'cat'.

Thanks,
NeilBrown

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 832 bytes --]