[Gluster-devel] semantics about OPEN in NFS

[Niels de Vos]

On Wed, Dec 14, 2016 at 06:54:27PM +0800, jin deng wrote:
> >
> >
> 
> > Te NFSv3 protocol does not have a OPEN procedure. When an NFSv3 client
> > wants to read/write a file, the operations are like:
> >
> >   1. LOOKUP of the filename, returns a filehandle on success
> >   2. WRITE data with offset in the filehandle
> >
> > A LOOKUP is like stat(), and the filehandle is a opaque structure that
> > uniquely identifies the file on the storage backend. A filehandle
> > basically identifies the filesystem/volume and the inode of the file so
> > that Gluster/NFS can find it again. For Gluster/NFS the filehandle
> > consists out of the Volume-ID and the GFID of the file.
> >
> > Our GlusterFS protocol (for the I/O on the bricks) have support for
> > procedures that accept a GFID (like a Gluster Volume wide inode). The
> > Gluster/NFS server uses these procedures exclusively, except for LOOKUP.
> >
> 
>  Thanks for your explain,Niels.I know  the operations which you
> mentioned.While my confusion is
> 
> that why the xlators such as "debug/io-stats" defines a "open" procedure if
> the NFSv3 protocol doesn't
> 
> require it.And when will these procedures be called? I haven't found any
> caller in the code of "server/nfs". Any
> 
> other top xlator will call that?

I do not expect that any of the xlators will call OPEN. From my
understanding of what you wrote, I assume that debug/io-stats is not
very functional when using Gluster/NFS.

You also seem to have conformed in your original email that the
statistics are not complete. Reporting that as a bug against the io-stat
xlator is the first step. If you are able to write a patch to create the
inode-context when it it missing, then you can send it to our Gerrit
instance for review:
  http://gluster.readthedocs.io/en/latest/Developer-guide/Simplified-Development-Workflow/

Thanks,
Niels
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