* Incorrect(?) use of open_state->stateid in pnfs
@ 2016-10-13 7:18 NeilBrown
2016-10-13 13:08 ` Trond Myklebust
0 siblings, 1 reply; 3+ messages in thread
From: NeilBrown @ 2016-10-13 7:18 UTC (permalink / raw)
To: Linux NFS Mailing List
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Suppose I open/create a file over pNFS and am given a WRITE delegation.
I then chmod the file (as rsync is wont to do) so the delegation is
immediately returned.
I then proceed to write, which triggers a LAYOUT_GET request. The
stateid for that request it taken from state->stateid, which is still
the delegation stateid. Naturally it gets NFS4ERR_BAD_STATEID.
When an OPEN is given a delegation, the delegation stateid gets copied
into ->stateid and the open stateid is left in ->open_stateid.
When the delegation is returned, this it done by inode, not open_state,
so it doesn't have easy access to reset the ->stateid. It could find
all the open_states and fix them up I guess it ....
Other than this usage in pnfs (which dates back to commit b1f69b754e and
is, I believe, incorrect) the ->stateid is *only* used to help find the
write state to recover when an error is reported and the state needs to
be recovered (... though the usage in nfs4_do_handle_exception()
introduced by 272289a3df is a bit different).
Anyway, no other code uses it when choosing a stateid to send in a
request. So no other code inadvertently uses the delegation stateid
after it has been returned.
How should this be fixed?
- have nfs_start_delegation_return() iterated over all open states
and copy the open_stateid over the stateid??
- have pnfs_update_layout() use ->open_stateid rather than ->stateid ??
I suspect that would be wrong.
- have pnfs_update_layout() use ->open_stateid if NFS_I()->delegation
is NULL ??
Something else?
The last seems easiest, but I'm not certain it is best.
Thanks,
NeilBrown
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* Re: Incorrect(?) use of open_state->stateid in pnfs
2016-10-13 7:18 Incorrect(?) use of open_state->stateid in pnfs NeilBrown
@ 2016-10-13 13:08 ` Trond Myklebust
2016-10-13 21:55 ` NeilBrown
0 siblings, 1 reply; 3+ messages in thread
From: Trond Myklebust @ 2016-10-13 13:08 UTC (permalink / raw)
To: NeilBrown; +Cc: List Linux NFS Mailing
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Incorrect(?) use of open_state->stateid in pnfs
2016-10-13 13:08 ` Trond Myklebust
@ 2016-10-13 21:55 ` NeilBrown
0 siblings, 0 replies; 3+ messages in thread
From: NeilBrown @ 2016-10-13 21:55 UTC (permalink / raw)
To: Trond Myklebust; +Cc: List Linux NFS Mailing
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On Fri, Oct 14 2016, Trond Myklebust wrote:
>> On Oct 13, 2016, at 03:18, NeilBrown <neilb@suse.com> wrote:
>>
>>
>> Suppose I open/create a file over pNFS and am given a WRITE delegation.
>> I then chmod the file (as rsync is wont to do) so the delegation is
>> immediately returned.
>> I then proceed to write, which triggers a LAYOUT_GET request. The
>> stateid for that request it taken from state->stateid, which is still
>> the delegation stateid. Naturally it gets NFS4ERR_BAD_STATEID.
>
> Umm… Why isn’t the client recovering open stateids as part of the delegation return? That would appear to be the root cause problem here.
Ahh.. that's where it happens. Of course. Thanks.
I was thinking that where would be no opens to recover because the
delegation wasn't used to complete any other opens. But there is more
to the recovery than that.
>
> Is this the latest upstream kernel?
No, it is 3.12 based. I now see that I am just missing
Commit: 5e99b532bb95 ("nfs4: reset states to use open_stateid when returning delegation voluntarily")
Thanks!
NeilBrown
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2016-10-13 13:08 ` Trond Myklebust
2016-10-13 21:55 ` NeilBrown
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