[pnfs] [PATCH 05/10] nfs41: NFSv4.1 callback structures

[Ricardo Labiaga]

On Wed, 2008-01-02 at 19:21 -0500, J. Bruce Fields wrote:
> On Wed, Jan 02, 2008 at 04:01:46PM -0800, Ricardo Labiaga wrote:
> > Adds new pointer to the rpc_xprt structure. Used to preallocate resources for
> > the backchannel and allocate backchannel requests.  Callbacks are not expected
> > to cause significant latency, so only one callback will be allowed at a time.
> 
> That's one callback per rpc_xprt?  (So roughly one per mounted nfsv4.1
> server?)
> 

Yes, that's correct, one callback per rpc_xprt.  Although I believe your
question just uncovered a bug.  The premise is that the client is able
to tell the server the number of backchannels it supports during session
negotiation.  I believe I have a problem where that a single rpc_xprt
can be shared by more than one session (I need to verify this).  If this
is true, then I have to figured out a different place to hang the
pre-allocated resources.

- ricardo



> --b.
> 
> > 
> > Signed-off-by: Ricardo Labiaga <ricardo.labiaga at netapp.com>
> > ---
> >  include/linux/sunrpc/xprt.h |   14 +++++++++++++-
> >  1 files changed, 13 insertions(+), 1 deletions(-)
> > 
> > diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
> > index b64d8df..6777793 100644
> > --- a/include/linux/sunrpc/xprt.h
> > +++ b/include/linux/sunrpc/xprt.h
> > @@ -170,7 +170,12 @@ struct rpc_xprt {
> >  	struct rpc_task *	snd_task;	/* Task blocked in send */
> >  #if defined(CONFIG_NFSD_V4_1)
> >  	struct svc_sock	       *svsk;           /* If this is a callback xprt */
> > -#endif
> > +#endif /* CONFIG_NFSD_V4_1 */
> > +#if defined(CONFIG_NFS_V4_1)
> > +	struct svc_serv		*serv;		/* The RPC service which will process the callback request */
> > +	unsigned long		bc_flags;	/* Backchannel flags */
> > +	struct rpc_rqst		*bc_rpc_rqst;	/* Preallocated backchannel rpc_rqst */
> > +#endif /* CONFIG_NFS_V4_1 */
> >  	struct list_head	recv;
> >  
> >  	struct {
> > @@ -189,6 +194,13 @@ struct rpc_xprt {
> >  	char *			address_strings[RPC_DISPLAY_MAX];
> >  };
> >  
> > +#if defined(CONFIG_NFS_V4_1)
> > +/*
> > + * Backchannel flags
> > + */
> > +#define	RPC_BC_PREALLOC_IN_USE	0x0001	/* Preallocated backchannel buffers in use */
> > +#endif /* CONFIG_NFS_V4_1 */
> > +
> >  struct xprt_create {
> >  	int			ident;		/* XPRT_TRANSPORT identifier */
> >  	struct sockaddr *	srcaddr;	/* optional local address */
> > -- 
> > 1.5.3.3
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