On Fri, Jan 9, 2015 at 9:33 AM, Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx> wrote: > On Fri, 9 Jan 2015 09:28:35 -0800 > Jeff Layton <jlayton@xxxxxxxxxxxxxxx> wrote: > >> On Fri, 9 Jan 2015 18:16:41 +0100 >> Christoph Hellwig <hch@xxxxxx> wrote: >> >> > On Fri, Jan 09, 2015 at 08:51:30AM -0800, Jeff Layton wrote: >> > > Ok, it'd be good to document that in some comments then for the sake of >> > > posterity (maybe it is later in the set -- I haven't gotten to the end >> > > yet). >> > >> > What kinds of comments do you expect? Not implementing unused features >> > of a protocol should be the default for anything in Linux. >> > >> >> I was thinking just a comment saying that ROC is always true in this >> implementation, or maybe consider eliminating the lg_roc field in >> struct nfsd4_layoutget altogether since it's currently always "1". >> >> It's a little confusing now since the encoder can handle the case where >> lg_roc is 0, but the rest of the code can't. >> >> > > Now, that said...I think that your ROC semantics are wrong here. You >> > > also have to take delegations into account. [1] >> > > >> > > Basically the semantics that you want are that nfsd should do all of >> > > the ROC stuff on last close iff there are no outstanding delegations or >> > > on delegreturn iff there are no opens. >> > > >> > > What we ended up doing in the unreleased code we have was to create a >> > > new per-client and per-file object (that we creatively called an >> > > "odstate"). An open stateid and a delegation stateid would hold a >> > > reference to this object which is put when those stateids are freed. >> > > When its refcount goes to zero, then we'd free any outstanding layouts >> > > on the file for that client and free the object. >> > > >> > > You probably want to do something similar here. >> > > >> > > [1]: Tom and Trond mentioned that there's a RFC5661 errata pending for >> > > this, but I don't see it right offhand. >> > >> > It would be good to look at the errata. While the idea of keeping >> > layouts around longer makes sense, I would only expect to do this >> > if they layout state was created based on a delegation stateid, not >> > a lock or open stateid. In that case having the layouts hang off >> > the "parent" stateid might be another option. >> >> I found it: >> >> http://www.rfc-editor.org/errata_search.php?rfc=5661&eid=3226 >> > > Oh, hmm...except that doesn't seem to have been updated according to > the discussion from around a year ago. See the thread entitled: > > [nfsv4] NFSv4.1 errata id 3226 (the return of return-on-close layouts) > > ...on thee nfsv4@xxxxxxxx mailing list. Trond mentions it there. > Perhaps we need to revise that errata? > Please see: http://www.rfc-editor.org/errata_search.php?eid=3901 -- Trond Myklebust Linux NFS client maintainer, PrimaryData trond.myklebust@xxxxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
