Gluster users - Nov 2016 - question about nfs lookup result

On 11/16/2016 06:38 PM, Pranith Kumar Karampuri wrote:
> Added people who know nfs code.
>
> On Wed, Nov 16, 2016 at 6:21 PM, jin deng <cheneydeng88 at gmail.com
> <mailto:cheneydeng88 at gmail.com>> wrote:
>
>     Hi all,
>         I'm reading the code of 3.6.9 version and got a question.And
I'm
>     not very familiar with the code,so I have to confirm it(I checked
>     the master branch,it's same with 3.6.9).
>
>         The question is about the 'lookup' operation of NFS.And
i'm with
>     this code flow:
>
>         nfs3_lookup (nfs3.c) ==> nfs3_fh_resolve_and_resume
>     ==> nfs3_fh_resolve_root ==> nfs3_fh_resolve_resume
>     ==> nfs3_fh_resolve_entry ==> nfs3_fh_resolve_entry_hard.
>
>     Now enter the "nfs_entry_loc_fill" and return with -1 which
means
>     the "parent" not found,so we have to do hard resolve about
the
>     parent. After doing a hard resolve,we get into the callback
>     "nfs3_fh_resolve_inode_lookup_cbk".And the callback has the
>     following code:
>
>     >>> memcpy (&cs->stbuf, buf, sizeof(*buf));
>     >>> memcpy (&cs->postparent, buf, sizeof(*postparent))
This must had been done  (and required) in case if this was the last 
entry(/inode) to be looked up.
>
>     I think we've just done a parent resolve,how could we assign the
>     parent result into the "stbuf" and "postparent".The
later two should
>     be the information of the child file/directory.Do i made a
>     misunderstand?
In case if it was not the last entry we fall through below code in 
"nfs3_fh_resolve_inode_lookup_cbk" -

         if (cs->resolventry)
                 nfs3_fh_resolve_entry_hard (cs);

Callback is "nfs3_fh_resolve_entry_lookup_cbk()" where in cs->stbuf
and
cs->postparent get overridden with the values corresponding to the child 
entry.

Thanks,
Soumya
>
>     Thanks advance for your help.
>
>     _______________________________________________
>     Gluster-users mailing list
>     Gluster-users at gluster.org <mailto:Gluster-users at
gluster.org>
>     http://www.gluster.org/mailman/listinfo/gluster-users
>     <http://www.gluster.org/mailman/listinfo/gluster-users>
>
>
>
>
> --
> Pranith

Thank you so much.Soumya,you make me more clear about the logic of the code.

I used to wonder the code was to handle the last resolve case.However i
followed

the "nfs3_fh_resolve_entry_hard" and I thought it would get the ret ==
-2
case and went

into the "nfs3_lookup_op" branch,and finally call the
"nfs3_call_resume".Seems has

no chance to call "nfs3_fh_resolve_entry_lookup_cbk" because it was a
LOOKUP

operation.Am i wrong again? :-)



2016-11-16 21:45 GMT+08:00 Soumya Koduri <skoduri at redhat.com>:
>
>
> On 11/16/2016 06:38 PM, Pranith Kumar Karampuri wrote:
>
>> Added people who know nfs code.
>>
>> On Wed, Nov 16, 2016 at 6:21 PM, jin deng <cheneydeng88 at gmail.com
>> <mailto:cheneydeng88 at gmail.com>> wrote:
>>
>>     Hi all,
>>         I'm reading the code of 3.6.9 version and got a
question.And I'm
>>     not very familiar with the code,so I have to confirm it(I checked
>>     the master branch,it's same with 3.6.9).
>>
>>         The question is about the 'lookup' operation of NFS.And
i'm with
>>     this code flow:
>>
>>         nfs3_lookup (nfs3.c) ==> nfs3_fh_resolve_and_resume
>>     ==> nfs3_fh_resolve_root ==> nfs3_fh_resolve_resume
>>     ==> nfs3_fh_resolve_entry ==> nfs3_fh_resolve_entry_hard.
>>
>>     Now enter the "nfs_entry_loc_fill" and return with -1
which means
>>     the "parent" not found,so we have to do hard resolve
about the
>>     parent. After doing a hard resolve,we get into the callback
>>     "nfs3_fh_resolve_inode_lookup_cbk".And the callback has
the
>>     following code:
>>
>>     >>> memcpy (&cs->stbuf, buf, sizeof(*buf));
>>     >>> memcpy (&cs->postparent, buf,
sizeof(*postparent))
>>
>
> This must had been done  (and required) in case if this was the last
> entry(/inode) to be looked up
>
>>     I think we've just done a parent resolve,how could we assign
the
>>     parent result into the "stbuf" and
"postparent".The later two should
>>     be the information of the child file/directory.Do i made a
>>     misunderstand?
>>
>
> In case if it was not the last entry we fall through below code in
> "nfs3_fh_resolve_inode_lookup_cbk" -
>
>         if (cs->resolventry)
>                 nfs3_fh_resolve_entry_hard (cs);
>
> Callback is "nfs3_fh_resolve_entry_lookup_cbk()" where in
cs->stbuf and
> cs->postparent get overridden with the values corresponding to the child
> entry.
>
> Thanks,
> Soumya
>
>
>>     Thanks advance for your help.
>>
>>     _______________________________________________
>>     Gluster-users mailing list
>>     Gluster-users at gluster.org <mailto:Gluster-users at
gluster.org>
>>     http://www.gluster.org/mailman/listinfo/gluster-users
>>     <http://www.gluster.org/mailman/listinfo/gluster-users>
>>
>>
>>
>>
>> --
>> Pranith
>>
>
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