clnt.c

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/*
 *  linux/net/sunrpc/rpcclnt.c
 *
 *  This file contains the high-level RPC interface.
 *  It is modeled as a finite state machine to support both synchronous
 *  and asynchronous requests.
 *
 *  -	RPC header generation and argument serialization.
 *  -	Credential refresh.
 *  -	TCP reconnect handling (when finished).
 *  -	Retry of operation when it is suspected the operation failed because
 *	of uid squashing on the server, or when the credentials were stale
 *	and need to be refreshed, or when a packet was damaged in transit.
 *	This may be have to be moved to the VFS layer.
 *
 *  NB: BSD uses a more intelligent approach to guessing when a request
 *  or reply has been lost by keeping the RTO estimate for each procedure.
 *  We currently make do with a constant timeout value.
 *
 *  Copyright (C) 1992,1993 Rick Sladkey <[e-mail]>
 *  Copyright (C) 1995,1996 Olaf Kirch <[e-mail]>
 */

#include <asm/system.h>

#include <linux/types.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/in.h>
#include <linux/utsname.h>

#include <linux/sunrpc/clnt.h>

#include <linux/nfs.h>


#define RPC_SLACK_SPACE		512	/* total overkill */

#ifdef RPC_DEBUG
# define RPCDBG_FACILITY	RPCDBG_CALL
#endif

static DECLARE_WAIT_QUEUE_HEAD(destroy_wait);


static void	call_reserve(struct rpc_task *task);
static void	call_reserveresult(struct rpc_task *task);
static void	call_allocate(struct rpc_task *task);
static void	call_encode(struct rpc_task *task);
static void	call_decode(struct rpc_task *task);
static void	call_bind(struct rpc_task *task);
static void	call_transmit(struct rpc_task *task);
static void	call_status(struct rpc_task *task);
static void	call_refresh(struct rpc_task *task);
static void	call_refreshresult(struct rpc_task *task);
static void	call_timeout(struct rpc_task *task);
static void	call_reconnect(struct rpc_task *task);
static void	child_reconnect(struct rpc_task *);
static void	child_reconnect_status(struct rpc_task *);
static u32 *	call_header(struct rpc_task *task);
static u32 *	call_verify(struct rpc_task *task);


/*
 * Create an RPC client
 * FIXME: This should also take a flags argument (as in task->tk_flags).
 * It's called (among others) from pmap_create_client, which may in
 * turn be called by an async task. In this case, rpciod should not be
 * made to sleep too long.
 */
struct rpc_clnt *
rpc_create_client(struct rpc_xprt *xprt, char *servname,
		  struct rpc_program *program, u32 vers, int flavor)
{
	struct rpc_version	*version;
	struct rpc_clnt		*clnt = NULL;

	dprintk("RPC: creating %s client for %s (xprt %p)\n",
		program->name, servname, xprt);

#ifdef RPC_DEBUG
	rpc_register_sysctl();
#endif

	if (!xprt)
		goto out;
	if (vers >= program->nrvers || !(version = program->version[vers]))
		goto out;

	clnt = (struct rpc_clnt *) rpc_allocate(0, sizeof(*clnt));
	if (!clnt)
		goto out_no_clnt;
	memset(clnt, 0, sizeof(*clnt));
	atomic_set(&clnt->cl_users, 0);

	clnt->cl_xprt     = xprt;
	clnt->cl_procinfo = version->procs;
	clnt->cl_maxproc  = version->nrprocs;
	clnt->cl_server   = servname;
	clnt->cl_protname = program->name;
	clnt->cl_port     = xprt->addr.sin_port;
	clnt->cl_prog     = program->number;
	clnt->cl_vers     = version->number;
	clnt->cl_prot     = xprt->prot;
	clnt->cl_stats    = program->stats;
	clnt->cl_bindwait = RPC_INIT_WAITQ("bindwait");

	if (!clnt->cl_port)
		clnt->cl_autobind = 1;

	if (!rpcauth_create(flavor, clnt))
		goto out_no_auth;

	/* save the nodename */
	clnt->cl_nodelen = strlen(system_utsname.nodename);
	if (clnt->cl_nodelen > UNX_MAXNODENAME)
		clnt->cl_nodelen = UNX_MAXNODENAME;
	memcpy(clnt->cl_nodename, system_utsname.nodename, clnt->cl_nodelen);
out:
	return clnt;

out_no_clnt:
	printk(KERN_INFO "RPC: out of memory in rpc_create_client\n");
	goto out;
out_no_auth:
	printk(KERN_INFO "RPC: Couldn't create auth handle (flavor %d)\n",
		flavor);
	rpc_free(clnt);
	clnt = NULL;
	goto out;
}

/*
 * Properly shut down an RPC client, terminating all outstanding
 * requests. Note that we must be certain that cl_oneshot and
 * cl_dead are cleared, or else the client would be destroyed
 * when the last task releases it.
 */
int
rpc_shutdown_client(struct rpc_clnt *clnt)
{
	dprintk("RPC: shutting down %s client for %s\n",
		clnt->cl_protname, clnt->cl_server);
	while (atomic_read(&clnt->cl_users)) {
#ifdef RPC_DEBUG
		dprintk("RPC: rpc_shutdown_client: client %s, tasks=%d\n",
			clnt->cl_protname, atomic_read(&clnt->cl_users));
#endif
		/* Don't let rpc_release_client destroy us */
		clnt->cl_oneshot = 0;
		clnt->cl_dead = 0;
		rpc_killall_tasks(clnt);
		sleep_on_timeout(&destroy_wait, 1*HZ);
	}
	return rpc_destroy_client(clnt);
}

/*
 * Delete an RPC client
 */
int
rpc_destroy_client(struct rpc_clnt *clnt)
{
	dprintk("RPC: destroying %s client for %s\n",
			clnt->cl_protname, clnt->cl_server);

	if (clnt->cl_auth) {
		rpcauth_destroy(clnt->cl_auth);
		clnt->cl_auth = NULL;
	}
	if (clnt->cl_xprt) {
		xprt_destroy(clnt->cl_xprt);
		clnt->cl_xprt = NULL;
	}
	rpc_free(clnt);
	return 0;
}

/*
 * Release an RPC client
 */
void
rpc_release_client(struct rpc_clnt *clnt)
{
	dprintk("RPC:      rpc_release_client(%p, %d)\n",
				clnt, atomic_read(&clnt->cl_users));

	if (!atomic_dec_and_test(&clnt->cl_users))
		return;
	wake_up(&destroy_wait);
	if (clnt->cl_oneshot || clnt->cl_dead)
		rpc_destroy_client(clnt);
}

/*
 * Default callback for async RPC calls
 */
static void
rpc_default_callback(struct rpc_task *task)
{
}

/*
 *	Export the signal mask handling for aysnchronous code that
 *	sleeps on RPC calls
 */
 
void rpc_clnt_sigmask(struct rpc_clnt *clnt, sigset_t *oldset)
{
	unsigned long	sigallow = sigmask(SIGKILL);
	unsigned long	irqflags;
	
	/* Turn off various signals */
	if (clnt->cl_intr) {
		struct k_sigaction *action = current->sig->action;
		if (action[SIGINT-1].sa.sa_handler == SIG_DFL)
			sigallow |= sigmask(SIGINT);
		if (action[SIGQUIT-1].sa.sa_handler == SIG_DFL)
			sigallow |= sigmask(SIGQUIT);
	}
	spin_lock_irqsave(&current->sigmask_lock, irqflags);
	*oldset = current->blocked;
	siginitsetinv(&current->blocked, sigallow & ~oldset->sig[0]);
	recalc_sigpending(current);
	spin_unlock_irqrestore(&current->sigmask_lock, irqflags);
}

void rpc_clnt_sigunmask(struct rpc_clnt *clnt, sigset_t *oldset)
{
	unsigned long	irqflags;
	
	spin_lock_irqsave(&current->sigmask_lock, irqflags);
	current->blocked = *oldset;
	recalc_sigpending(current);
	spin_unlock_irqrestore(&current->sigmask_lock, irqflags);
}

/*
 * New rpc_call implementation
 */
int rpc_call_sync(struct rpc_clnt *clnt, struct rpc_message *msg, int flags)
{
	struct rpc_task	my_task, *task = &my_task;
	sigset_t	oldset;
	int		status;

	/* If this client is slain all further I/O fails */
	if (clnt->cl_dead) 
		return -EIO;

	if (flags & RPC_TASK_ASYNC) {
		printk("rpc_call_sync: Illegal flag combination for synchronous task\n");
		flags &= ~RPC_TASK_ASYNC;
	}

	rpc_clnt_sigmask(clnt, &oldset);		

	/* Create/initialize a new RPC task */
	rpc_init_task(task, clnt, NULL, flags);
	rpc_call_setup(task, msg, 0);

	/* Set up the call info struct and execute the task */
	if (task->tk_status == 0)
		status = rpc_execute(task);
	else {
		status = task->tk_status;
		rpc_release_task(task);
	}

	rpc_clnt_sigunmask(clnt, &oldset);		

	return status;
}

/*
 * New rpc_call implementation
 */
int
rpc_call_async(struct rpc_clnt *clnt, struct rpc_message *msg, int flags,
	       rpc_action callback, void *data)
{
	struct rpc_task	*task;
	sigset_t	oldset;
	int		status;

	/* If this client is slain all further I/O fails */
	if (clnt->cl_dead) 
		return -EIO;

	flags |= RPC_TASK_ASYNC;

	rpc_clnt_sigmask(clnt, &oldset);		

	/* Create/initialize a new RPC task */
	if (!callback)
		callback = rpc_default_callback;
	status = -ENOMEM;
	if (!(task = rpc_new_task(clnt, callback, flags)))
		goto out;
	task->tk_calldata = data;

	rpc_call_setup(task, msg, 0);

	/* Set up the call info struct and execute the task */
	if (task->tk_status == 0)
		status = rpc_execute(task);
	else {
		status = task->tk_status;
		rpc_release_task(task);
	}

out:
	rpc_clnt_sigunmask(clnt, &oldset);		

	return status;
}


void
rpc_call_setup(struct rpc_task *task, struct rpc_message *msg, int flags)
{
	task->tk_msg   = *msg;
	task->tk_flags |= flags;
	/* Bind the user cred */
	if (task->tk_msg.rpc_cred != NULL) {
		rpcauth_holdcred(task);
	} else
		rpcauth_bindcred(task);

	if (task->tk_status == 0)
		task->tk_action = call_reserve;
	else
		task->tk_action = NULL;

	/* Increment call count */
	if (task->tk_msg.rpc_proc < task->tk_client->cl_maxproc)
		rpcproc_count(task->tk_client, task->tk_msg.rpc_proc)++;
}

/*
 * Restart an (async) RPC call. Usually called from within the
 * exit handler.
 */
void
rpc_restart_call(struct rpc_task *task)
{
	if (RPC_ASSASSINATED(task))
		return;

	task->tk_action = call_reserve;
	rpcproc_count(task->tk_client, task->tk_msg.rpc_proc)++;
}

/*
 * 1.	Reserve an RPC call slot
 */
static void
call_reserve(struct rpc_task *task)
{
	struct rpc_clnt	*clnt = task->tk_client;

	if (task->tk_msg.rpc_proc > clnt->cl_maxproc) {
		printk(KERN_WARNING "%s (vers %d): bad procedure number %d\n",
			clnt->cl_protname, clnt->cl_vers, task->tk_msg.rpc_proc);
		rpc_exit(task, -EIO);
		return;
	}

	dprintk("RPC: %4d call_reserve\n", task->tk_pid);
	if (!rpcauth_uptodatecred(task)) {
		task->tk_action = call_refresh;
		return;
	}

	task->tk_status  = 0;
	task->tk_action  = call_reserveresult;
	task->tk_timeout = clnt->cl_timeout.to_resrvval;
	clnt->cl_stats->rpccnt++;
	xprt_reserve(task);
}

/*
 * 1b.	Grok the result of xprt_reserve()
 */
static void
call_reserveresult(struct rpc_task *task)
{
	int status = task->tk_status;

	dprintk("RPC: %4d call_reserveresult (status %d)\n",
				task->tk_pid, task->tk_status);
	/*
	 * After a call to xprt_reserve(), we must have either
	 * a request slot or else an error status.
	 */
	if ((task->tk_status >= 0 && !task->tk_rqstp) ||
	    (task->tk_status < 0 && task->tk_rqstp))
		printk(KERN_ERR "call_reserveresult: status=%d, request=%p??\n",
		 task->tk_status, task->tk_rqstp);

	if (task->tk_status >= 0) {
		task->tk_action = call_allocate;
		return;
	}

	task->tk_status = 0;
	switch (status) {
	case -EAGAIN:
	case -ENOBUFS:
		task->tk_timeout = task->tk_client->cl_timeout.to_resrvval;
		task->tk_action = call_reserve;
		break;
	case -ETIMEDOUT:
		dprintk("RPC: task timed out\n");
		task->tk_action = call_timeout;
		break;
	default:
		if (!task->tk_rqstp) {
			printk(KERN_INFO "RPC: task has no request, exit EIO\n");
			rpc_exit(task, -EIO);
		} else
			rpc_exit(task, status);
	}
}

/*
 * 2.	Allocate the buffer. For details, see sched.c:rpc_malloc.
 *	(Note: buffer memory is freed in rpc_task_release).
 */
static void
call_allocate(struct rpc_task *task)
{
	struct rpc_clnt	*clnt = task->tk_client;
	unsigned int	bufsiz;

	dprintk("RPC: %4d call_allocate (status %d)\n", 
				task->tk_pid, task->tk_status);
	task->tk_action = call_encode;
	if (task->tk_buffer)
		return;

	/* FIXME: compute buffer requirements more exactly using
	 * auth->au_wslack */
	bufsiz = rpcproc_bufsiz(clnt, task->tk_msg.rpc_proc) + RPC_SLACK_SPACE;

	if ((task->tk_buffer = rpc_malloc(task, bufsiz << 1)) != NULL)