On Fri, 2008-10-17 at 13:48 -0400, J. Bruce Fields wrote:
> On Wed, Oct 15, 2008 at 05:00:24PM -0400, andros@xxxxxxxxxx wrote:
> > From: Andy Adamson <andros@xxxxxxxxxx>
> >
> > For EOS, NFSD compound RPC deferred processing should restart operation which
> > caused the deferral.
> >
> > Add a callback and a defer_data pointer in svc_rqst to enable svc_defer to
> > save partial result state in the deferral request.
> >
> > Add page pointer storage to svc_deferred_req to cache the pages holding the
> > partially processed request.
> >
> > Add callbacks and a defer_data pointer in svc_deferred_request to enable
> > svc_deferred_recv to restore and release the partial result state.
> >
> > Signed-off-by: Andy Adamson<andros@xxxxxxxxx>
>
> Could you fix the missing space there?
Oops..:)
>
> > ---
> > include/linux/sunrpc/svc.h | 10 ++++++++++
> > net/sunrpc/svc_xprt.c | 20 +++++++++++++++-----
> > 2 files changed, 25 insertions(+), 5 deletions(-)
> >
> > diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
> > index dc69068..46a4097 100644
> > --- a/include/linux/sunrpc/svc.h
> > +++ b/include/linux/sunrpc/svc.h
> > @@ -215,6 +215,9 @@ struct svc_rqst {
> > struct svc_cred rq_cred; /* auth info */
> > void * rq_xprt_ctxt; /* transport specific context ptr */
> > struct svc_deferred_req*rq_deferred; /* deferred request we are replaying */
> > + /* callback to save deferred request state */
> > + void (*rq_save_state)(struct svc_rqst *, struct svc_deferred_req *);
> > + void *rq_defer_data; /* defer state data to save */
> >
> > size_t rq_xprt_hlen; /* xprt header len */
> > struct xdr_buf rq_arg;
> > @@ -323,6 +326,13 @@ struct svc_deferred_req {
> > union svc_addr_u daddr; /* where reply must come from */
> > struct cache_deferred_req handle;
> > size_t xprt_hlen;
> > + /* callbacks to restore and release deferred request state
> > + * set in rq_save_state */
> > + void (*restore_state)(struct svc_rqst *, struct svc_deferred_req *);
> > + void (*release_state)(struct svc_deferred_req *);
> > + void *defer_data; /* defer state data */
> > + struct page *respages[RPCSVC_MAXPAGES];
> > + short resused;
> > int argslen;
> > __be32 args[0];
> > };
> > diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
> > index e46c825..531b325 100644
> > --- a/net/sunrpc/svc_xprt.c
> > +++ b/net/sunrpc/svc_xprt.c
> > @@ -876,6 +876,8 @@ static void svc_revisit(struct cache_deferred_req *dreq, int too_many)
> > struct svc_xprt *xprt = dr->xprt;
> >
> > if (too_many) {
> > + if (dr->release_state)
> > + dr->release_state(dr);
> > svc_xprt_put(xprt);
> > kfree(dr);
> > return;
> > @@ -902,10 +904,10 @@ static void svc_revisit(struct cache_deferred_req *dreq, int too_many)
> > static struct cache_deferred_req *svc_defer(struct cache_req *req)
> > {
> > struct svc_rqst *rqstp = container_of(req, struct svc_rqst, rq_chandle);
> > - struct svc_deferred_req *dr;
> > + struct svc_deferred_req *dr = NULL;
> >
> > if (rqstp->rq_arg.page_len)
> > - return NULL; /* if more than a page, give up FIXME */
> > + goto out; /* if more than a page, give up FIXME */
> > if (rqstp->rq_deferred) {
> > dr = rqstp->rq_deferred;
> > rqstp->rq_deferred = NULL;
> > @@ -914,9 +916,9 @@ static struct cache_deferred_req *svc_defer(struct cache_req *req)
> > size_t size;
> > /* FIXME maybe discard if size too large */
> > size = sizeof(struct svc_deferred_req) + rqstp->rq_arg.len;
> > - dr = kmalloc(size, GFP_KERNEL);
> > + dr = kzalloc(size, GFP_KERNEL);
> > if (dr == NULL)
> > - return NULL;
> > + goto out;
> >
> > dr->handle.owner = rqstp->rq_server;
> > dr->prot = rqstp->rq_prot;
> > @@ -935,7 +937,13 @@ static struct cache_deferred_req *svc_defer(struct cache_req *req)
> > dr->xprt = rqstp->rq_xprt;
> >
> > dr->handle.revisit = svc_revisit;
> > - return &dr->handle;
> > + if (rqstp->rq_save_state)
> > + rqstp->rq_save_state(rqstp, dr);
> > +out:
> > + rqstp->rq_defer_data = NULL;
> > + rqstp->rq_save_state = NULL;
> > +
> > + return dr ? &dr->handle: NULL;
>
> I may not be thinking this through clearly, but: I think the correct
> place to initialize rq_defer_data and rq_save_state is not here but at
> the very start of request processing (in svc_recv or at the top of
> svc_process). We shouldn't depend on svc_defer()--it may never get
> called.
In patch 3/3, nfsd4_proc_compound sets the rq_defer_data and
rq_defer_state prior to operation processing, and then sets them back to
NULL after operation processing, so the initialization to NULL in
svc_defer is not needed.
We could indeed initialize these fields at the top of svc_process in
which case the setting to NULL at the end of operation processing in
nfsd4_proc_compound would not be needed. Your call.
-->Andy
> --b.
>
> > }
> >
> > /*
> > @@ -959,6 +967,8 @@ static int svc_deferred_recv(struct svc_rqst *rqstp)
> > rqstp->rq_xprt_hlen = dr->xprt_hlen;
> > rqstp->rq_daddr = dr->daddr;
> > rqstp->rq_respages = rqstp->rq_pages;
> > + if (dr->restore_state)
> > + dr->restore_state(rqstp, dr);
> > return (dr->argslen<<2) - dr->xprt_hlen;
> > }
> >
> > --
> > 1.5.4.3
> >
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