On Thu, May 13, 2010 at 11:31 AM, Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote:
> On 05/13/2010 06:17 PM, William A. (Andy) Adamson wrote:
>> On Thu, May 13, 2010 at 10:40 AM, Benny Halevy <bhalevy@xxxxxxxxxxx> wrote:
>>> On May. 13, 2010, 17:19 +0300, "William A. (Andy) Adamson" <androsadamson@xxxxxxxxx> wrote:
>>>> On Thu, May 13, 2010 at 4:40 AM, Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote:
>>>>> I've tested the patch:
>>>>> FIXME: async layout return
>>>>>
>>>>> And there is a missing small hunk
>>>>>
>>>>> I have tested with this patch and it is a very good patch
>>>>> that should also go into 2.6.33. It is necessary in the rare
>>>>> case when one inode have more then one open_context.
>>>>
>>>> Do you mean more than one open context per open owner?
>>>
>>> What we see is one "regular" open context and one which is the layout_commit_ctx
>>
>> Isn't that a BUG?
>>
>> Here is what we're seeing:
>>
>> nfs_file_release->nfs_release->nfs_file_clear_open_context->__put_nfs_open_context->
>> NFS_PROTO(inode)->close_context->nfs4_close_sync->__nfs4_close->pnfs_layoutcommit_inode,
>>
>> This is the same code that Boaz's 'missing small hunk' adds the wait
>> to the pnfs_layout_commit_inode to. This is good, because when
>> __nfs4_close is called with sync, every thing must be sent/returned
>> prior to the nfs_do_close call.
>>
>> But there is still a problem. Here is the __nfs4_close call (with out
>> the wait that Boaz added)
>>
>> if (nfsi->layoutcommit_ctx)
>> pnfs_layoutcommit_inode(state->inode, 0);
>> if (has_layout(nfsi) && nfsi->layout.roc_iomode) {
>> struct nfs4_pnfs_layout_segment range;
>>
>> range.iomode = nfsi->layout.roc_iomode;
>> range.offset = 0;
>> range.length = NFS4_MAX_UINT64;
>> pnfs_return_layout(state->inode, &range, NULL,
>> RETURN_FILE);
>>
>> Note that a pnfs_return_layout which is always 'sync' (async with wait
>> for completion). So the (currently) async LAYOUTCOMMIT call returns,
>> and a LAYOUTRETURN is put on the wire
>>
>> Then the LAYOUTCOMMIT rpc_call_done routine calls
>> pnfs_layoutcommit_done which calls put_nfs_open_context. If the open
>> context is different from the open context that was put by
>> nfs_file_release, then
>>
>> pnfs_layoutcommit_done->put_nfs_open_context-> ..... ->__nfs4_close
>> and the return on close LAYOUTRETURN is sent again!
>>
>> Of couse this second LAYOUTRETURN either gets a zero stateid, or uses
>> the same stateid as the first LAYOUTRETURN, and the reply to the
>> second LAYOUTRETURN will result in a NFS4ERR_BAD_STATEID .....
>>
>> This will occur whether the LAYOUTCOMMIT is async or sync as they both
>> call pnfs_layoutcommit_done.
>>
>> I need to understand why there are two open contexts. On the face of
>> it, it seems wrong.
>>
>> We also add a pointer to the open context in the nfs_write_data, and
>> in the pnfs_layoutcommit_data. Do we take a reference on the open data
>> in theses cases? .
>>
>> -->Andy
>>
>>
>
> Yes on all acounts. This is what Benny's patch is fixing please try it out
> it is most important (Add my small fix)
Is this what you mean?
With Benny's patch, with return-on-close set and the layoutcommit_ctx
different from the open context that caused the __nfs4_close:
The (now) sync LAYOUTCOMMIT triggered from the nfs_file_release
__nfs4_close() will complete prior to calling the return-on-close
LAYOUTRETURN call. Since pnfs_layoutcommit_done is still called,
put_nfs_open_context will be call on the layoutconmit_ctx (saved in
pnfs_layoutcommit_data->ctx) and __nfs4_close will be called.
In _this_ instance of calling __nfs4_close (from
pnfs_layoutcommit_done), the nfsi->layoutcommit_ctx pointer is null so
the pnfs_layoutcommit_inode call is skipped, and pnfs_return_layout
is called. Since it is also a sync call, pnfs_layoutcommit_done does
not return until it is complete. So the layout is returned, the layout
is freed (all layout segments 'cause the range covers the whole file)
and pnfs_layoutcommit_inode returns to the FIRST __nfs4_close (from
nfs_file_release)
Now since return-on-close is set, pnfs_layout_return is called (in the
nfs_file_release __nfs4_close). This LAYOUTRETURN call will never go
on the wire because the first pnfs_layout_return (from the
pnfs_layoutcommit_done __nfs4_close) has removed the layout segment,
and all is well.
Sheese.
--->Andy
>
> And about the multiple contexts I don't understand as well but the fact of it
> is that an nfs_inode has an list_head of open_contexts and we must deal properly
> with when that happens. (BTW with 2.6.34 Kernel it happens regularly as in
> prev kernels it almost never trigger.)
>
> Benny's patch takes care of that and I've done heavy testing of it I can see cases
> of more then one contexts and it works correctly.
>
> But I too would like to understand when is it that an inode can have more then
> one open_context
>
> Boaz
>
>>
>>>
>>> Benny
>>>
>>>>
>>>> -->Andy
>>>>
>>>>>
>>>>> (For some reason I see that happening much more in 2.6.34
>>>>> I don't understand why)
>>>>>
>>>>> Boaz
>>>>> ---
>>>>> git diff --stat -p -M
>>>>> fs/nfs/nfs4state.c | 2 +-
>>>>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>>>>
>>>>> diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
>>>>> index 15c8bc8..6dbe893 100644
>>>>> --- a/fs/nfs/nfs4state.c
>>>>> +++ b/fs/nfs/nfs4state.c
>>>>> @@ -590,7 +590,7 @@ static void __nfs4_close(struct path *path, struct nfs4_state *state, fmode_t fm
>>>>> struct nfs_inode *nfsi = NFS_I(state->inode);
>>>>>
>>>>> if (nfsi->layoutcommit_ctx)
>>>>> - pnfs_layoutcommit_inode(state->inode, 0);
>>>>> + pnfs_layoutcommit_inode(state->inode, wait);
>>>>> if (has_layout(nfsi) && nfsi->layout.roc_iomode) {
>>>>> struct nfs4_pnfs_layout_segment range;
>>>>>
>>>>> --
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