[PATCH] kNFSd: Provide support for request deferral and revisit.

cache.c gets code to allow a 'request' to be referred pending
an update of a cache item, and revisited when the item is
updates.

svcsock.c gets code to store the relevant part of a request on deferral, and
to re-queue it when the cache item that caused the deferral is
filled in.

4 files changed, 51 insertions, 7 deletions

diff --git a/include/linux/nfsd/export.h b/include/linux/nfsd/export.h
index 8e658be46c87..4d692bb2797f 100644
--- a/include/linux/nfsd/export.h
+++ b/include/linux/nfsd/export.h
@@ -86,13 +86,16 @@ void			nfsd_export_shutdown(void);
 void			exp_readlock(void);
 void			exp_readunlock(void);
 struct svc_expkey *	exp_find_key(struct auth_domain *clp, 
-				     int fsid_type, u32 *fsidv);
+				     int fsid_type, u32 *fsidv,
+				     struct cache_req *reqp);
 struct svc_export *	exp_get_by_name(struct auth_domain *clp,
 					struct vfsmount *mnt,
-					struct dentry *dentry);
+					struct dentry *dentry,
+					struct cache_req *reqp);
 struct svc_export *	exp_parent(struct auth_domain *clp,
 				   struct vfsmount *mnt,
-				   struct dentry *dentry);
+				   struct dentry *dentry,
+				   struct cache_req *reqp);
 int			exp_rootfh(struct auth_domain *, 
 					char *path, struct knfsd_fh *, int maxsize);
 int			exp_pseudoroot(struct auth_domain *, struct svc_fh *fhp);
@@ -108,16 +111,17 @@ static inline void exp_put(struct svc_export *exp)
 }
 
 static inline struct svc_export *
-exp_find(struct auth_domain *clp, int fsid_type, u32 *fsidv)
+exp_find(struct auth_domain *clp, int fsid_type, u32 *fsidv,
+	 struct cache_req *reqp)
 {
-	struct svc_expkey *ek = exp_find_key(clp, fsid_type, fsidv);
+	struct svc_expkey *ek = exp_find_key(clp, fsid_type, fsidv, reqp);
 	if (ek && !IS_ERR(ek)) {
 		struct svc_export *exp = ek->ek_export;
 		int err;
 		cache_get(&exp->h);
 		expkey_put(&ek->h, &svc_expkey_cache);
 		if (exp &&
-		    (err = cache_check(&svc_export_cache, &exp->h))) 
+		    (err = cache_check(&svc_export_cache, &exp->h, reqp)))
 			exp = ERR_PTR(err);
 		return exp;
 	} else
diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h
index efbf31293a6c..ef69dfa21817 100644
--- a/include/linux/sunrpc/cache.h
+++ b/include/linux/sunrpc/cache.h
@@ -86,6 +86,25 @@ struct cache_detail {
 };
 
 
+/* this must be embedded in any request structure that
+ * identifies an object that will want a callback on
+ * a cache fill
+ */
+struct cache_req {
+	struct cache_deferred_req *(*defer)(struct cache_req *req);
+};
+/* this must be embedded in a deferred_request that is being
+ * delayed awaiting cache-fill
+ */
+struct cache_deferred_req {
+	struct list_head	hash;	/* on hash chain */
+	struct list_head	recent; /* on fifo */
+	struct cache_head	*item;  /* cache item we wait on */
+	time_t			recv_time;
+	void			(*revisit)(struct cache_deferred_req *req,
+					   int too_many);
+};
+
 /*
  * just like a template in C++, this macro does cache lookup
  * for us.
@@ -206,6 +225,9 @@ RTN *FNAME ARGS										\
 
 	     
 
+extern void cache_defer_req(struct cache_req *req, struct cache_head *item);
+extern void cache_revisit_request(struct cache_head *item);
+
 static inline struct cache_head  *cache_get(struct cache_head *h)
 {
 	atomic_inc(&h->refcnt);
@@ -230,7 +252,7 @@ extern void cache_init(struct cache_head *h);
 extern void cache_fresh(struct cache_detail *detail,
 			struct cache_head *head, time_t expiry);
 extern int cache_check(struct cache_detail *detail,
-		       struct cache_head *h);
+		       struct cache_head *h, struct cache_req *rqstp);
 extern int cache_clean(void);
 extern void cache_flush(void);
 extern void cache_purge(struct cache_detail *detail);
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 95e6b8d20fd1..36fde12f8d3e 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -101,6 +101,7 @@ struct svc_rqst {
 	struct auth_ops *	rq_authop;	/* authentication flavour */
 	struct svc_cred		rq_cred;	/* auth info */
 	struct sk_buff *	rq_skbuff;	/* fast recv inet buffer */
+	struct svc_deferred_req*rq_deferred;	/* deferred request we are replaying */
 	struct svc_buf		rq_defbuf;	/* default buffer */
 	struct svc_buf		rq_argbuf;	/* argument buffer */
 	struct svc_buf		rq_resbuf;	/* result buffer */
@@ -121,6 +122,9 @@ struct svc_rqst {
 						 * reserved for this request
 						 */
 
+	struct cache_req	rq_chandle;	/* handle passed to caches for 
+						 * request delaying 
+						 */
 	/* Catering to nfsd */
 	struct auth_domain *	rq_client;	/* RPC peer info */
 	struct svc_cacherep *	rq_cacherep;	/* cache info */
@@ -132,6 +136,16 @@ struct svc_rqst {
 	wait_queue_head_t	rq_wait;	/* synchronization */
 };
 
+struct svc_deferred_req {
+	struct svc_serv		*serv;
+	u32			prot;	/* protocol (UDP or TCP) */
+	struct sockaddr_in	addr;
+	struct svc_sock		*svsk;	/* where reply must go */
+	struct cache_deferred_req handle;
+	int			argslen;
+	u32			args[0];
+};
+
 /*
  * RPC program
  */
diff --git a/include/linux/sunrpc/svcsock.h b/include/linux/sunrpc/svcsock.h
index af29406521bc..2f90342e4c76 100644
--- a/include/linux/sunrpc/svcsock.h
+++ b/include/linux/sunrpc/svcsock.h
@@ -31,9 +31,13 @@ struct svc_sock {
 #define	SK_QUED		5			/* on serv->sk_sockets */
 #define	SK_DEAD		6			/* socket closed */
 #define	SK_CHNGBUF	7			/* need to change snd/rcv buffer sizes */
+#define	SK_DEFERRED	8			/* request on sk_deferred */
 
 	int			sk_reserved;	/* space on outq that is reserved */
 
+	struct list_head	sk_deferred;	/* deferred requests that need to
+						 * be revisted */
+
 	int			(*sk_recvfrom)(struct svc_rqst *rqstp);
 	int			(*sk_sendto)(struct svc_rqst *rqstp);