Re: ext3 and SPEC SFS Run rules.

[Neil Brown]

On Monday July 26, akpm@xxxxxxxx wrote:
> >    2. For NFS Version 3, the server adheres to the protocol specification. 
> > In particular the requirement that for STABLE write requests and COMMIT 
> > operations the NFS server must not reply to the NFS client before any 
> > modified file system data or metadata, with the exception of access times, 
> > are written to stable storage for that specific or related operation. See 
> > RFC 1813, NFSv3 protocol specification for a definition of STABLE and 
> > COMMIT for NFS write requests.

Providing you use the "sync" export option, the Linux kNFSd should
meet this requirement.

> >    3. For NFS Version 3, operations which are specified to return wcc data 
> > must, in all cases, return TRUE and the correct attribute data. Those 
> > operations are:
> > 
> >       NFS Version 3
> >       SETATTR
> >       READLINK
> >       CREATE
> >       MKDIR
> >       SYMLINK
> >       MKNOD
> >       REMOVE
> >       RMDIR
> >       RENAME
> >       LINK
> 
> To confirm this we'd need to undertake an audit of the server
> implementation, and we'll need to ask Neil about it.

To help with the audit: the wcc data is set by "fh_unlock".  i.e. when
a filehandle is unlocked (up(i_sem)) a copy of the state information
is taken and included where appropriate in the reply.

The only place that I am aware of where we *do*not* return wcc data is
for the WRITE request (which you have not listed).  As the underlying
filesystem is left to do whatever locking it thinks is appropriate,
and vfs_write does none, nfsd is not in a position to lock it itself
against sys_write and so cannot record before and after stat
information that is atomic w.r.t the update.

NeilBrown
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/