Re: [RFC] Reinstate NFS exportability for JFFS2.

David Woodhouse
2008-08-01T01:00:41Z

On Thu, 2008-07-31 at 20:53 -0400, Chuck Lever wrote:
> For now it is sufficient, IMO. NFSv4 doesn't implement a readdirplus
> operation, and the performance benefits of NFSv3 readdirplus are
> equivocal -- there isn't a strong desire to replicate the complexity
> of NFSv3 readdirplus in NFSv4. I'm not even sure you can do it even
> with a single compound RPC, so even in the long run NFSv4 may not ever
> have the locking issues that NFSv3 does here.

AFAICT NFSv4 does have the same recursion issues already. The call trace
goes fs->readdir() ... nfsd4_encode_dirent() ...
nfsd4_encode_dirent_fattr() ... lookup_one_len() ... fs->lookup().

Or am I mistaken?

> I agree with Neil, though -- as a reviewer, I think the architecture
> of your solution is valid, but would need to audit these pretty
> closely to get a sense of the individual correctness/appropriateness
> of each change.

The important part to review is this one, which is fairly close to what
XFS has been doing (for local access too) for a long time already:

http://git.infradead.org/users/dwmw2/nfsexport-2.6.git?a=commitdiff;h=37f3aae5380eb4ef23a77f3f52b8849a18cee188

--
David Woodhouse Open Source Technology Centre
David.Woodhouse@intel.com Intel Corporation