SUNRPC: Make RPC portmapper use per-transport storage

Move connection and bind state that was maintained in the rpc_clnt
structure to the rpc_xprt structure.  This will allow the creation of
a clean API for plugging in different types of bind mechanisms.

This brings improvements such as the elimination of a single spin lock to
control serialization for all in-kernel RPC binding.  A set of per-xprt
bitops is used to serialize tasks during RPC binding, just like it now
works for making RPC transport connections.

Test-plan:
Destructive testing (unplugging the network temporarily).  Connectathon
with UDP and TCP.  NFSv2/3 and NFSv4 mounting should be carefully checked.
Probably need to rig a server where certain services aren't running, or
that returns an error for some typical operation.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

include/linux/sunrpc/clnt.h

@@ -18,18 +18,6 @@
 #include <linux/sunrpc/timer.h>
 #include <asm/signal.h>
 
-/*
- * This defines an RPC port mapping
- */
-struct rpc_portmap {
-	__u32			pm_prog;
-	__u32			pm_vers;
-	__u32			pm_prot;
-	__u16			pm_port;
-	unsigned char		pm_binding : 1;	/* doing a getport() */
-	struct rpc_wait_queue	pm_bindwait;	/* waiting on getport() */
-};
-
 struct rpc_inode;
 
 /*
@@ -40,7 +28,9 @@ struct rpc_clnt {
 	atomic_t		cl_users;	/* number of references */
 	struct rpc_xprt *	cl_xprt;	/* transport */
 	struct rpc_procinfo *	cl_procinfo;	/* procedure info */
-	u32			cl_maxproc;	/* max procedure number */
+	u32			cl_prog,	/* RPC program number */
+				cl_vers,	/* RPC version number */
+				cl_maxproc;	/* max procedure number */
 
 	char *			cl_server;	/* server machine name */
 	char *			cl_protname;	/* protocol name */
@@ -55,7 +45,6 @@ struct rpc_clnt {
 				cl_dead     : 1;/* abandoned */
 
 	struct rpc_rtt *	cl_rtt;		/* RTO estimator data */
-	struct rpc_portmap *	cl_pmap;	/* port mapping */
 
 	int			cl_nodelen;	/* nodename length */
 	char 			cl_nodename[UNX_MAXNODENAME];
@@ -64,14 +53,8 @@ struct rpc_clnt {
 	struct dentry *		cl_dentry;	/* inode */
 	struct rpc_clnt *	cl_parent;	/* Points to parent of clones */
 	struct rpc_rtt		cl_rtt_default;
-	struct rpc_portmap	cl_pmap_default;
 	char			cl_inline_name[32];
 };
-#define cl_timeout		cl_xprt->timeout
-#define cl_prog			cl_pmap->pm_prog
-#define cl_vers			cl_pmap->pm_vers
-#define cl_port			cl_pmap->pm_port
-#define cl_prot			cl_pmap->pm_prot
 
 /*
  * General RPC program info

include/linux/sunrpc/xprt.h

@@ -138,6 +138,7 @@ struct rpc_xprt {
 	unsigned int		tsh_size;	/* size of transport specific
 						   header */
 
+	struct rpc_wait_queue	binding;	/* requests waiting on rpcbind */
 	struct rpc_wait_queue	sending;	/* requests waiting to send */
 	struct rpc_wait_queue	resend;		/* requests waiting to resend */
 	struct rpc_wait_queue	pending;	/* requests in flight */
@@ -270,6 +271,7 @@ int			xs_setup_tcp(struct rpc_xprt *xprt, struct rpc_timeout *to);
 #define XPRT_CONNECTING		(2)
 #define XPRT_CLOSE_WAIT		(3)
 #define XPRT_BOUND		(4)
+#define XPRT_BINDING		(5)
 
 static inline void xprt_set_connected(struct rpc_xprt *xprt)
 {
@@ -328,6 +330,18 @@ static inline void xprt_clear_bound(struct rpc_xprt *xprt)
 	clear_bit(XPRT_BOUND, &xprt->state);
 }
 
+static inline void xprt_clear_binding(struct rpc_xprt *xprt)
+{
+	smp_mb__before_clear_bit();
+	clear_bit(XPRT_BINDING, &xprt->state);
+	smp_mb__after_clear_bit();
+}
+
+static inline int xprt_test_and_set_binding(struct rpc_xprt *xprt)
+{
+	return test_and_set_bit(XPRT_BINDING, &xprt->state);
+}
+
 #endif /* __KERNEL__*/
 
 #endif /* _LINUX_SUNRPC_XPRT_H */

net/sunrpc/clnt.c

@@ -147,13 +147,10 @@ rpc_new_client(struct rpc_xprt *xprt, char *servname,
 	clnt->cl_procinfo = version->procs;
 	clnt->cl_maxproc  = version->nrprocs;
 	clnt->cl_protname = program->name;
-	clnt->cl_pmap	  = &clnt->cl_pmap_default;
 	clnt->cl_prog     = program->number;
 	clnt->cl_vers     = version->number;
-	clnt->cl_prot     = xprt->prot;
 	clnt->cl_stats    = program->stats;
 	clnt->cl_metrics  = rpc_alloc_iostats(clnt);
-	rpc_init_wait_queue(&clnt->cl_pmap_default.pm_bindwait, "bindwait");
 
 	if (!xprt_bound(clnt->cl_xprt))
 		clnt->cl_autobind = 1;
@@ -243,8 +240,6 @@ rpc_clone_client(struct rpc_clnt *clnt)
 	atomic_set(&new->cl_users, 0);
 	new->cl_parent = clnt;
 	atomic_inc(&clnt->cl_count);
-	/* Duplicate portmapper */
-	rpc_init_wait_queue(&new->cl_pmap_default.pm_bindwait, "bindwait");
 	/* Turn off autobind on clones */
 	new->cl_autobind = 0;
 	new->cl_oneshot = 0;
@@ -254,8 +249,7 @@ rpc_clone_client(struct rpc_clnt *clnt)
 	rpc_init_rtt(&new->cl_rtt_default, clnt->cl_xprt->timeout.to_initval);
 	if (new->cl_auth)
 		atomic_inc(&new->cl_auth->au_count);
-	new->cl_pmap		= &new->cl_pmap_default;
-	new->cl_metrics         = rpc_alloc_iostats(clnt);
+	new->cl_metrics = rpc_alloc_iostats(clnt);
 	return new;
 out_no_clnt:
 	printk(KERN_INFO "RPC: out of memory in %s\n", __FUNCTION__);

net/sunrpc/pmap_clnt.c

@@ -24,11 +24,57 @@
 #define PMAP_UNSET		2
 #define PMAP_GETPORT		3
 
+struct portmap_args {
+	u32			pm_prog;
+	u32			pm_vers;
+	u32			pm_prot;
+	unsigned short		pm_port;
+	struct rpc_task *	pm_task;
+};
+
 static struct rpc_procinfo	pmap_procedures[];
 static struct rpc_clnt *	pmap_create(char *, struct sockaddr_in *, int, int);
-static void			pmap_getport_done(struct rpc_task *);
+static void			pmap_getport_done(struct rpc_task *, void *);
 static struct rpc_program	pmap_program;
-static DEFINE_SPINLOCK(pmap_lock);
+
+static void pmap_getport_prepare(struct rpc_task *task, void *calldata)
+{
+	struct portmap_args *map = calldata;
+	struct rpc_message msg = {
+		.rpc_proc	= &pmap_procedures[PMAP_GETPORT],
+		.rpc_argp	= map,
+		.rpc_resp	= &map->pm_port,
+	};
+
+	rpc_call_setup(task, &msg, 0);
+}
+
+static inline struct portmap_args *pmap_map_alloc(void)
+{
+	return kmalloc(sizeof(struct portmap_args), GFP_NOFS);
+}
+
+static inline void pmap_map_free(struct portmap_args *map)
+{
+	kfree(map);
+}
+
+static void pmap_map_release(void *data)
+{
+	pmap_map_free(data);
+}
+
+static const struct rpc_call_ops pmap_getport_ops = {
+	.rpc_call_prepare	= pmap_getport_prepare,
+	.rpc_call_done		= pmap_getport_done,
+	.rpc_release		= pmap_map_release,
+};
+
+static inline void pmap_wake_portmap_waiters(struct rpc_xprt *xprt)
+{
+	xprt_clear_binding(xprt);
+	rpc_wake_up(&xprt->binding);
+}
 
 /*
  * Obtain the port for a given RPC service on a given host. This one can
@@ -37,67 +83,71 @@ static DEFINE_SPINLOCK(pmap_lock);
 void
 rpc_getport(struct rpc_task *task, struct rpc_clnt *clnt)
 {
-	struct rpc_portmap *map = clnt->cl_pmap;
-	struct sockaddr_in *sap = &clnt->cl_xprt->addr;
-	struct rpc_message msg = {
-		.rpc_proc	= &pmap_procedures[PMAP_GETPORT],
-		.rpc_argp	= map,
-		.rpc_resp	= &clnt->cl_port,
-		.rpc_cred	= NULL
-	};
+	struct rpc_xprt *xprt = task->tk_xprt;
+	struct sockaddr_in *sap = &xprt->addr;
+	struct portmap_args *map;
 	struct rpc_clnt	*pmap_clnt;
-	struct rpc_task	*child;
+	struct rpc_task *child;
 
-	dprintk("RPC: %4d rpc_getport(%s, %d, %d, %d)\n",
+	dprintk("RPC: %4d rpc_getport(%s, %u, %u, %d)\n",
 			task->tk_pid, clnt->cl_server,
-			map->pm_prog, map->pm_vers, map->pm_prot);
+			clnt->cl_prog, clnt->cl_vers, xprt->prot);
 
 	/* Autobind on cloned rpc clients is discouraged */
 	BUG_ON(clnt->cl_parent != clnt);
 
-	spin_lock(&pmap_lock);
-	if (map->pm_binding) {
-		rpc_sleep_on(&map->pm_bindwait, task, NULL, NULL);
-		spin_unlock(&pmap_lock);
+	if (xprt_test_and_set_binding(xprt)) {
+		task->tk_status = -EACCES;	/* tell caller to check again */
+		rpc_sleep_on(&xprt->binding, task, NULL, NULL);
 		return;
 	}
-	map->pm_binding = 1;
-	spin_unlock(&pmap_lock);
+
+	/* Someone else may have bound if we slept */
+	if (xprt_bound(xprt)) {
+		task->tk_status = 0;
+		goto bailout_nofree;
+	}
+
+	map = pmap_map_alloc();
+	if (!map) {
+		task->tk_status = -ENOMEM;
+		goto bailout_nofree;
+	}
+	map->pm_prog = clnt->cl_prog;
+	map->pm_vers = clnt->cl_vers;
+	map->pm_prot = xprt->prot;
+	map->pm_port = 0;
+	map->pm_task = task;
 
 	pmap_clnt = pmap_create(clnt->cl_server, sap, map->pm_prot, 0);
 	if (IS_ERR(pmap_clnt)) {
 		task->tk_status = PTR_ERR(pmap_clnt);
 		goto bailout;
 	}
-	task->tk_status = 0;
 
-	/*
-	 * Note: rpc_new_child will release client after a failure.
-	 */
-	if (!(child = rpc_new_child(pmap_clnt, task)))
+	child = rpc_run_task(pmap_clnt, RPC_TASK_ASYNC, &pmap_getport_ops, map);
+	if (IS_ERR(child)) {
+		task->tk_status = -EIO;
 		goto bailout;
+	}
+	rpc_release_task(child);
 
-	/* Setup the call info struct */
-	rpc_call_setup(child, &msg, 0);
+	rpc_sleep_on(&xprt->binding, task, NULL, NULL);
 
-	/* ... and run the child task */
 	task->tk_xprt->stat.bind_count++;
-	rpc_run_child(task, child, pmap_getport_done);
 	return;
 
 bailout:
-	spin_lock(&pmap_lock);
-	map->pm_binding = 0;
-	rpc_wake_up(&map->pm_bindwait);
-	spin_unlock(&pmap_lock);
-	rpc_exit(task, -EIO);
+	pmap_map_free(map);
+bailout_nofree:
+	pmap_wake_portmap_waiters(xprt);
 }
 
 #ifdef CONFIG_ROOT_NFS
 int
 rpc_getport_external(struct sockaddr_in *sin, __u32 prog, __u32 vers, int prot)
 {
-	struct rpc_portmap map = {
+	struct portmap_args map = {
 		.pm_prog	= prog,
 		.pm_vers	= vers,
 		.pm_prot	= prot,
@@ -133,32 +183,32 @@ rpc_getport_external(struct sockaddr_in *sin, __u32 prog, __u32 vers, int prot)
 #endif
 
 static void
-pmap_getport_done(struct rpc_task *task)
+pmap_getport_done(struct rpc_task *child, void *data)
 {
-	struct rpc_clnt	*clnt = task->tk_client;
+	struct portmap_args *map = data;
+	struct rpc_task *task = map->pm_task;
 	struct rpc_xprt *xprt = task->tk_xprt;
-	struct rpc_portmap *map = clnt->cl_pmap;
-
-	dprintk("RPC: %4d pmap_getport_done(status %d, port %d)\n",
-			task->tk_pid, task->tk_status, clnt->cl_port);
+	int status = child->tk_status;
 
-	if (task->tk_status < 0) {
-		/* Make the calling task exit with an error */
+	if (status < 0) {
+		/* Portmapper not available */
 		xprt->ops->set_port(xprt, 0);
-		task->tk_action = rpc_exit_task;
-	} else if (clnt->cl_port == 0) {
-		/* Program not registered */
+		task->tk_status = status;
+	} else if (map->pm_port == 0) {
+		/* Requested RPC service wasn't registered */
 		xprt->ops->set_port(xprt, 0);
-		rpc_exit(task, -EACCES);
+		task->tk_status = -EACCES;
 	} else {
-		xprt->ops->set_port(xprt, clnt->cl_port);
+		/* Succeeded */
+		xprt->ops->set_port(xprt, map->pm_port);
 		xprt_set_bound(xprt);
-		clnt->cl_port = htons(clnt->cl_port);
+		task->tk_status = 0;
 	}
-	spin_lock(&pmap_lock);
-	map->pm_binding = 0;
-	rpc_wake_up(&map->pm_bindwait);
-	spin_unlock(&pmap_lock);
+
+	dprintk("RPC: %4d pmap_getport_done(status %d, port %u)\n",
+			child->tk_pid, child->tk_status, map->pm_port);
+
+	pmap_wake_portmap_waiters(xprt);
 }
 
 /*
@@ -172,7 +222,7 @@ rpc_register(u32 prog, u32 vers, int prot, unsigned short port, int *okay)
 		.sin_family	= AF_INET,
 		.sin_addr.s_addr = htonl(INADDR_LOOPBACK),
 	};
-	struct rpc_portmap	map = {
+	struct portmap_args	map = {
 		.pm_prog	= prog,
 		.pm_vers	= vers,
 		.pm_prot	= prot,
@@ -239,7 +289,7 @@ pmap_create(char *hostname, struct sockaddr_in *srvaddr, int proto, int privileg
  * XDR encode/decode functions for PMAP
  */
 static int
-xdr_encode_mapping(struct rpc_rqst *req, u32 *p, struct rpc_portmap *map)
+xdr_encode_mapping(struct rpc_rqst *req, u32 *p, struct portmap_args *map)
 {
 	dprintk("RPC: xdr_encode_mapping(%d, %d, %d, %d)\n",
 		map->pm_prog, map->pm_vers, map->pm_prot, map->pm_port);

net/sunrpc/xprt.c

@@ -928,6 +928,7 @@ static struct rpc_xprt *xprt_setup(int proto, struct sockaddr_in *ap, struct rpc
 	xprt->last_used = jiffies;
 	xprt->cwnd = RPC_INITCWND;
 
+	rpc_init_wait_queue(&xprt->binding, "xprt_binding");
 	rpc_init_wait_queue(&xprt->pending, "xprt_pending");
 	rpc_init_wait_queue(&xprt->sending, "xprt_sending");
 	rpc_init_wait_queue(&xprt->resend, "xprt_resend");