Re: question about nfs lookup result

[jin deng <cheneydeng88@xxxxxxxxx>]

sorry,I read you patch( http://review.gluster.org/14911),that fix the problem.Thanks very much.

2016-11-16 22:38 GMT+08:00 jin deng <cheneydeng88@xxxxxxxxx>:

2016-11-16 22:30 GMT+08:00 Soumya Koduri <skoduri@xxxxxxxxxx>:

On 11/16/2016 07:38 PM, jin deng wrote:

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? :-)

You are right :)...for LOOKUP fop, we go to "nfs3_call_resume" which is nfs3_lookup_resume and the callback is "nfs3svc_lookup_cbk" where in we are not updating cs->stbuf. But we seem to be constructing lookup reply (nfs3_lookup_reply) using 'buf' directly returned for the child entry instead of using cs->stbuf. Maybe that's the reason it was working well till now.
FYI - there was an issue in the lookup logic code path which we fixed as part of http://review.gluster.org/14911 . I will not be surprised if there are any more lurking around :)

  

 hmm...seems still has a problem.As the "cs->hardresolved" has been set to 1 in "nfs3_fh_resolve_inode_hard".The "nfs3_lookup_resume" callback will not

 get into the "nfs3svc_lookup_cbk".Instead,the "nfs3_lookup_resume" will terminate at here as I thought:

 if (cs->hardresolved) {

stat = NFS3_OK;

nfs3_fh_build_child_fh (&cs->parent, &cs->stbuf, &newfh);

goto nfs3err;

}

I wonder if this works fine because the NFS client always resolve the parent first, not very sure.

 

Thanks,
Soumya

2016-11-16 21:45 GMT+08:00 Soumya Koduri <skoduri@xxxxxxxxxx
<mailto:skoduri@xxxxxxxxxx>>:



    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@xxxxxxxxx <mailto:cheneydeng88@xxxxxxxxx>
        <mailto:cheneydeng88@xxxxxxxxx <mailto:cheneydeng88@xxxxxxxxx>>>

        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.

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        --
        Pranith

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