Re-implement the client side of rpc.lockd in the kernel. This implementation

provides the correct semantics for flock(2) style locks which are used by the
lockf(1) command line tool and the pidfile(3) library. It also implements
recovery from server restarts and ensures that dirty cache blocks are written
to the server before obtaining locks (allowing multiple clients to use file
locking to safely share data).

Sponsored by:	Isilon Systems
PR:		94256
MFC after:	2 weeks

1 files changed, 88 insertions, 10 deletions

diff --git a/sys/rpc/clnt.h b/sys/rpc/clnt.h
index 4d6a778..03e3112 100644
--- a/sys/rpc/clnt.h
+++ b/sys/rpc/clnt.h
@@ -62,6 +62,7 @@
 #include <rpc/clnt_stat.h>
 #include <sys/cdefs.h>
 #ifdef _KERNEL
+#include <sys/refcount.h>
 #include <rpc/netconfig.h>
 #else
 #include <netconfig.h>
@@ -109,6 +110,23 @@ struct rpc_err {
 #define	re_lb		ru.RE_lb
 };
 
+#ifdef _KERNEL
+/*
+ * Functions of this type may be used to receive notification when RPC
+ * calls have to be re-transmitted etc.
+ */
+typedef void rpc_feedback(int cmd, int procnum, void *);
+
+/*
+ * A structure used with CLNT_CALL_EXT to pass extra information used
+ * while processing an RPC call.
+ */
+struct rpc_callextra {
+	AUTH		*rc_auth;	/* auth handle to use for this call */
+	rpc_feedback	*rc_feedback;	/* callback for retransmits etc. */
+	void		*rc_feedback_arg; /* argument for callback */
+};
+#endif
 
 /*
  * Client rpc handle.
@@ -116,12 +134,35 @@ struct rpc_err {
  * Client is responsible for initializing auth, see e.g. auth_none.c.
  */
 typedef struct __rpc_client {
+#ifdef _KERNEL
+	volatile u_int cl_refs;			/* reference count */
+	AUTH	*cl_auth;			/* authenticator */
+	struct clnt_ops {
+		/* call remote procedure */
+		enum clnt_stat	(*cl_call)(struct __rpc_client *,
+		    struct rpc_callextra *, rpcproc_t, xdrproc_t, void *,
+		    xdrproc_t, void *, struct timeval);
+		/* abort a call */
+		void		(*cl_abort)(struct __rpc_client *);
+		/* get specific error code */
+		void		(*cl_geterr)(struct __rpc_client *,
+					struct rpc_err *);
+		/* frees results */
+		bool_t		(*cl_freeres)(struct __rpc_client *,
+					xdrproc_t, void *);
+		/* destroy this structure */
+		void		(*cl_destroy)(struct __rpc_client *);
+		/* the ioctl() of rpc */
+		bool_t          (*cl_control)(struct __rpc_client *, u_int,
+				    void *);
+	} *cl_ops;
+#else
 	AUTH	*cl_auth;			/* authenticator */
 	struct clnt_ops {
 		/* call remote procedure */
 		enum clnt_stat	(*cl_call)(struct __rpc_client *,
-				    rpcproc_t, xdrproc_t, void *, xdrproc_t,
-				        void *, struct timeval);
+		    rpcproc_t, xdrproc_t, void *, xdrproc_t,
+		    void *, struct timeval);
 		/* abort a call */
 		void		(*cl_abort)(struct __rpc_client *);
 		/* get specific error code */
@@ -136,12 +177,12 @@ typedef struct __rpc_client {
 		bool_t          (*cl_control)(struct __rpc_client *, u_int,
 				    void *);
 	} *cl_ops;
+#endif
 	void 			*cl_private;	/* private stuff */
 	char			*cl_netid;	/* network token */
 	char			*cl_tp;		/* device name */
 } CLIENT;
 
-
 /*
  * Timers used for the pseudo-transport protocol when using datagrams
  */
@@ -154,8 +195,10 @@ struct rpc_timers {
 /*      
  * Feedback values used for possible congestion and rate control
  */
-#define FEEDBACK_REXMIT1	1	/* first retransmit */
-#define FEEDBACK_OK		2	/* no retransmits */    
+#define FEEDBACK_OK		1	/* no retransmits */    
+#define FEEDBACK_REXMIT1	2	/* first retransmit */
+#define FEEDBACK_REXMIT2	3	/* second and subsequent retransmit */
+#define FEEDBACK_RECONNECT	4	/* client reconnect */
 
 /* Used to set version of portmapper used in broadcast */
   
@@ -171,6 +214,30 @@ struct rpc_timers {
  *
  */
 
+#ifdef _KERNEL
+#define CLNT_ACQUIRE(rh)			\
+	refcount_acquire(&(rh)->cl_refs)
+#define CLNT_RELEASE(rh)			\
+	if (refcount_release(&(rh)->cl_refs))	\
+		CLNT_DESTROY(rh)
+
+/*
+ * enum clnt_stat
+ * CLNT_CALL_EXT(rh, ext, proc, xargs, argsp, xres, resp, timeout)
+ * 	CLIENT *rh;
+ *	struct rpc_callextra *ext;
+ *	rpcproc_t proc;
+ *	xdrproc_t xargs;
+ *	void *argsp;
+ *	xdrproc_t xres;
+ *	void *resp;
+ *	struct timeval timeout;
+ */
+#define	CLNT_CALL_EXT(rh, ext, proc, xargs, argsp, xres, resp, secs)	\
+	((*(rh)->cl_ops->cl_call)(rh, ext, proc, xargs,		\
+		argsp, xres, resp, secs))
+#endif
+
 /*
  * enum clnt_stat
  * CLNT_CALL(rh, proc, xargs, argsp, xres, resp, timeout)
@@ -182,12 +249,21 @@ struct rpc_timers {
  *	void *resp;
  *	struct timeval timeout;
  */
-#define	CLNT_CALL(rh, proc, xargs, argsp, xres, resp, secs) \
-	((*(rh)->cl_ops->cl_call)(rh, proc, xargs, \
+#ifdef _KERNEL
+#define	CLNT_CALL(rh, proc, xargs, argsp, xres, resp, secs)		\
+	((*(rh)->cl_ops->cl_call)(rh, NULL, proc, xargs,	\
 		argsp, xres, resp, secs))
-#define	clnt_call(rh, proc, xargs, argsp, xres, resp, secs) \
-	((*(rh)->cl_ops->cl_call)(rh, proc, xargs, \
+#define	clnt_call(rh, proc, xargs, argsp, xres, resp, secs)		\
+	((*(rh)->cl_ops->cl_call)(rh, NULL, proc, xargs,	\
 		argsp, xres, resp, secs))
+#else
+#define	CLNT_CALL(rh, proc, xargs, argsp, xres, resp, secs)		\
+	((*(rh)->cl_ops->cl_call)(rh, proc, xargs,	\
+		argsp, xres, resp, secs))
+#define	clnt_call(rh, proc, xargs, argsp, xres, resp, secs)		\
+	((*(rh)->cl_ops->cl_call)(rh, proc, xargs,	\
+		argsp, xres, resp, secs))
+#endif
 
 /*
  * void
@@ -262,6 +338,8 @@ struct rpc_timers {
 #define CLGET_WAITCHAN		22	/* get string used in msleep call */
 #define CLSET_INTERRUPTIBLE	23	/* set interruptible flag */
 #define CLGET_INTERRUPTIBLE	24	/* set interruptible flag */
+#define CLSET_RETRIES		25	/* set retry count for reconnect */
+#define CLGET_RETRIES		26	/* get retry count for reconnect */
 #endif
 
 
@@ -534,6 +612,7 @@ __END_DECLS
 #define rpc_createerr		(*(__rpc_createerr()))
 #endif
 
+#ifndef _KERNEL
 /*
  * The simplified interface:
  * enum clnt_stat
@@ -612,7 +691,6 @@ extern enum clnt_stat rpc_broadcast_exp(const rpcprog_t, const rpcvers_t,
 					const int, const char *);
 __END_DECLS
 
-#ifndef _KERNEL
 /* For backward compatibility */
 #include <rpc/clnt_soc.h>
 #endif