xprt.c

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/*
 *  linux/net/sunrpc/xprt.c
 *
 *  This is a generic RPC call interface supporting congestion avoidance,
 *  and asynchronous calls.
 *
 *  The interface works like this:
 *
 *  -	When a process places a call, it allocates a request slot if
 *	one is available. Otherwise, it sleeps on the backlog queue
 *	(xprt_reserve).
 *  -	Next, the caller puts together the RPC message, stuffs it into
 *	the request struct, and calls xprt_call().
 *  -	xprt_call transmits the message and installs the caller on the
 *	socket's wait list. At the same time, it installs a timer that
 *	is run after the packet's timeout has expired.
 *  -	When a packet arrives, the data_ready handler walks the list of
 *	pending requests for that socket. If a matching XID is found, the
 *	caller is woken up, and the timer removed.
 *  -	When no reply arrives within the timeout interval, the timer is
 *	fired by the kernel and runs xprt_timer(). It either adjusts the
 *	timeout values (minor timeout) or wakes up the caller with a status
 *	of -ETIMEDOUT.
 *  -	When the caller receives a notification from RPC that a reply arrived,
 *	it should release the RPC slot, and process the reply.
 *	If the call timed out, it may choose to retry the operation by
 *	adjusting the initial timeout value, and simply calling rpc_call
 *	again.
 *
 *  Support for async RPC is done through a set of RPC-specific scheduling
 *  primitives that `transparently' work for processes as well as async
 *  tasks that rely on callbacks.
 *
 *  Copyright (C) 1995-1997, Olaf Kirch <[e-mail]>
 *
 *  TCP callback races fixes (C) 1998 Red Hat Software <[e-mail]>
 *  TCP send fixes (C) 1998 Red Hat Software <[e-mail]>
 *  TCP NFS related read + write fixes
 *   (C) 1999 Dave Airlie, University of Limerick, Ireland <[e-mail]>
 *
 *  Rewrite of larges part of the code in order to stabilize TCP stuff.
 *  Fix behaviour when socket buffer is full.
 *   (C) 1999 Trond Myklebust <[e-mail]>
 */

#define __KERNEL_SYSCALLS__

#include <linux/version.h>
#include <linux/types.h>
#include <linux/malloc.h>
#include <linux/capability.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/net.h>
#include <linux/mm.h>
#include <linux/udp.h>
#include <linux/unistd.h>
#include <linux/sunrpc/clnt.h>
#include <linux/file.h>

#include <net/sock.h>
#include <net/checksum.h>
#include <net/udp.h>

#include <asm/uaccess.h>

/* Following value should be > 32k + RPC overhead */
#define XPRT_MIN_WRITE_SPACE (35000 + SOCK_MIN_WRITE_SPACE)

extern spinlock_t rpc_queue_lock;

/*
 * Local variables
 */

/* Spinlock for critical sections in the code. */
spinlock_t xprt_sock_lock = SPIN_LOCK_UNLOCKED;
spinlock_t xprt_lock = SPIN_LOCK_UNLOCKED;

#ifdef RPC_DEBUG
# undef  RPC_DEBUG_DATA
# define RPCDBG_FACILITY	RPCDBG_XPRT
#endif

#ifndef MAX
# define MAX(a, b)	((a) > (b)? (a) : (b))
# define MIN(a, b)	((a) < (b)? (a) : (b))
#endif

/*
 * Local functions
 */
static void	xprt_request_init(struct rpc_task *, struct rpc_xprt *);
static void	do_xprt_transmit(struct rpc_task *);
static void	xprt_reserve_status(struct rpc_task *task);
static void	xprt_disconnect(struct rpc_xprt *);
static void	xprt_reconn_status(struct rpc_task *task);
static struct socket *xprt_create_socket(int, struct rpc_timeout *);
static int	xprt_bind_socket(struct rpc_xprt *, struct socket *);
static void	xprt_remove_pending(struct rpc_xprt *);

#ifdef RPC_DEBUG_DATA
/*
 * Print the buffer contents (first 128 bytes only--just enough for
 * diropres return).
 */
static void
xprt_pktdump(char *msg, u32 *packet, unsigned int count)
{
	u8	*buf = (u8 *) packet;
	int	j;

	dprintk("RPC:      %s\n", msg);
	for (j = 0; j < count && j < 128; j += 4) {
		if (!(j & 31)) {
			if (j)
				dprintk("\n");
			dprintk("0x%04x ", j);
		}
		dprintk("%02x%02x%02x%02x ",
			buf[j], buf[j+1], buf[j+2], buf[j+3]);
	}
	dprintk("\n");
}
#else
static inline void
xprt_pktdump(char *msg, u32 *packet, unsigned int count)
{
	/* NOP */
}
#endif

/*
 * Look up RPC transport given an INET socket
 */
static inline struct rpc_xprt *
xprt_from_sock(struct sock *sk)
{
	return (struct rpc_xprt *) sk->user_data;
}

/*
 *	Adjust the iovec to move on 'n' bytes
 */
 
extern inline void
xprt_move_iov(struct msghdr *msg, struct iovec *niv, unsigned amount)
{
	struct iovec *iv=msg->msg_iov;
	int i;
	
	/*
	 *	Eat any sent iovecs
	 */
	while (iv->iov_len <= amount) {
		amount -= iv->iov_len;
		iv++;
		msg->msg_iovlen--;
	}

	/*
	 *	And chew down the partial one
	 */
	niv[0].iov_len = iv->iov_len-amount;
	niv[0].iov_base =((unsigned char *)iv->iov_base)+amount;
	iv++;

	/*
	 *	And copy any others
	 */
	for(i = 1; i < msg->msg_iovlen; i++)
		niv[i]=*iv++;

	msg->msg_iov=niv;
}

/*
 * Write data to socket.
 */
static inline int
xprt_sendmsg(struct rpc_xprt *xprt, struct rpc_rqst *req)
{
	struct socket	*sock = xprt->sock;
	struct msghdr	msg;
	mm_segment_t	oldfs;
	int		result;
	int		slen = req->rq_slen - req->rq_bytes_sent;
	struct iovec	niv[MAX_IOVEC];

	if (slen <= 0)
		return 0;

	if (!sock)
		return -ENOTCONN;

	xprt_pktdump("packet data:",
				req->rq_svec->iov_base,
				req->rq_svec->iov_len);

	msg.msg_flags   = MSG_DONTWAIT|MSG_NOSIGNAL;
	msg.msg_iov	= req->rq_svec;
	msg.msg_iovlen	= req->rq_snr;
	msg.msg_name	= (struct sockaddr *) &xprt->addr;
	msg.msg_namelen = sizeof(xprt->addr);
	msg.msg_control = NULL;
	msg.msg_controllen = 0;

	/* Dont repeat bytes */
	if (req->rq_bytes_sent)
		xprt_move_iov(&msg, niv, req->rq_bytes_sent);

	oldfs = get_fs(); set_fs(get_ds());
	result = sock_sendmsg(sock, &msg, slen);
	set_fs(oldfs);

	dprintk("RPC:      xprt_sendmsg(%d) = %d\n", slen, result);

	if (result >= 0)
		return result;

	switch (result) {
	case -ECONNREFUSED:
		/* When the server has died, an ICMP port unreachable message
		 * prompts ECONNREFUSED.
		 */
		break;
	case -EAGAIN:
		if (test_bit(SOCK_NOSPACE, &sock->flags))
			result = -ENOMEM;
		break;
	case -ENOTCONN:
	case -EPIPE:
		/* connection broken */
		if (xprt->stream)
			result = -ENOTCONN;
		break;
	default:
		printk(KERN_NOTICE "RPC: sendmsg returned error %d\n", -result);
	}
	return result;
}

/*
 * Read data from socket
 */
static int
xprt_recvmsg(struct rpc_xprt *xprt, struct iovec *iov, int nr, unsigned len, unsigned shift)
{
	struct socket	*sock = xprt->sock;
	struct msghdr	msg;
	mm_segment_t	oldfs;
	struct iovec	niv[MAX_IOVEC];
	int		result;

	if (!sock)
		return -ENOTCONN;

	msg.msg_flags   = MSG_DONTWAIT|MSG_NOSIGNAL;
	msg.msg_iov	= iov;
	msg.msg_iovlen	= nr;
	msg.msg_name	= NULL;
	msg.msg_namelen = 0;
	msg.msg_control = NULL;
	msg.msg_controllen = 0;

	/* Adjust the iovec if we've already filled it */
	if (shift)
		xprt_move_iov(&msg, niv, shift);

	oldfs = get_fs(); set_fs(get_ds());
	result = sock_recvmsg(sock, &msg, len, MSG_DONTWAIT);
	set_fs(oldfs);

	dprintk("RPC:      xprt_recvmsg(iov %p, len %d) = %d\n",
						iov, len, result);
	return result;
}


/*
 * Adjust RPC congestion window
 * We use a time-smoothed congestion estimator to avoid heavy oscillation.
 */
static void
xprt_adjust_cwnd(struct rpc_xprt *xprt, int result)
{
	unsigned long	cwnd;

	if (xprt->nocong)
		return;
	spin_lock_bh(&xprt_sock_lock);
	cwnd = xprt->cwnd;
	if (result >= 0) {
		if (xprt->cong < cwnd || time_before(jiffies, xprt->congtime))
			goto out;
		/* The (cwnd >> 1) term makes sure
		 * the result gets rounded properly. */
		cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
		if (cwnd > RPC_MAXCWND)
			cwnd = RPC_MAXCWND;
		else
			pprintk("RPC: %lu %ld cwnd\n", jiffies, cwnd);
		xprt->congtime = jiffies + ((cwnd * HZ) << 2) / RPC_CWNDSCALE;
		dprintk("RPC:      cong %08lx, cwnd was %08lx, now %08lx, "
			"time %ld ms\n", xprt->cong, xprt->cwnd, cwnd,
			(xprt->congtime-jiffies)*1000/HZ);
	} else if (result == -ETIMEDOUT) {
		if ((cwnd >>= 1) < RPC_CWNDSCALE)
			cwnd = RPC_CWNDSCALE;
		xprt->congtime = jiffies + ((cwnd * HZ) << 3) / RPC_CWNDSCALE;
		dprintk("RPC:      cong %ld, cwnd was %ld, now %ld, "
			"time %ld ms\n", xprt->cong, xprt->cwnd, cwnd,
			(xprt->congtime-jiffies)*1000/HZ);
		pprintk("RPC: %lu %ld cwnd\n", jiffies, cwnd);
	}

	xprt->cwnd = cwnd;
 out:
	spin_unlock_bh(&xprt_sock_lock);
}

/*
 * Adjust timeout values etc for next retransmit
 */
int
xprt_adjust_timeout(struct rpc_timeout *to)
{
	if (to->to_retries > 0) {
		if (to->to_exponential)
			to->to_current <<= 1;
		else
			to->to_current += to->to_increment;
		if (to->to_maxval && to->to_current >= to->to_maxval)
			to->to_current = to->to_maxval;
	} else {
		if (to->to_exponential)
			to->to_initval <<= 1;
		else
			to->to_initval += to->to_increment;
		if (to->to_maxval && to->to_initval >= to->to_maxval)
			to->to_initval = to->to_maxval;
		to->to_current = to->to_initval;
	}

	if (!to->to_current) {
		printk(KERN_WARNING "xprt_adjust_timeout: to_current = 0!\n");
		to->to_current = 5 * HZ;
	}
	pprintk("RPC: %lu %s\n", jiffies,
			to->to_retries? "retrans" : "timeout");
	return to->to_retries-- > 0;
}

/*
 * Close down a transport socket
 */
static void
xprt_close(struct rpc_xprt *xprt)
{
	struct socket	*sock = xprt->sock;
	struct sock	*sk = xprt->inet;

	if (!sk)
		return;

	xprt->inet = NULL;
	xprt->sock = NULL;

	sk->user_data    = NULL;
	sk->data_ready   = xprt->old_data_ready;
	sk->state_change = xprt->old_state_change;
	sk->write_space  = xprt->old_write_space;

	xprt_disconnect(xprt);
	sk->no_check	 = 0;

	sock_release(sock);
	/*
	 *	TCP doesnt require the rpciod now - other things may
	 *	but rpciod handles that not us.
	 */
	if(xprt->stream)
		rpciod_down();
}

/*
 * Mark a transport as disconnected
 */
static void
xprt_disconnect(struct rpc_xprt *xprt)
{
	dprintk("RPC:      disconnected transport %p\n", xprt);
	xprt_clear_connected(xprt);
	xprt_remove_pending(xprt);
	rpc_wake_up_status(&xprt->pending, -ENOTCONN);
}

/*
 * Reconnect a broken TCP connection.
 */
void
xprt_reconnect(struct rpc_task *task)
{
	struct rpc_xprt	*xprt = task->tk_xprt;
	struct socket	*sock = xprt->sock;
	struct sock	*inet = xprt->inet;
	int		status;

	dprintk("RPC: %4d xprt_reconnect %p connected %d\n",
				task->tk_pid, xprt, xprt_connected(xprt));
	if (xprt->shutdown)
		return;

	if (!xprt->stream)
		return;

	if (!xprt->addr.sin_port) {
		task->tk_status = -EIO;
		return;
	}

	spin_lock(&xprt_lock);
	if (xprt->connecting) {
		task->tk_timeout = 0;
		rpc_sleep_on(&xprt->reconn, task, NULL, NULL);
		spin_unlock(&xprt_lock);
		return;
	}
	xprt->connecting = 1;
	spin_unlock(&xprt_lock);

	status = -ENOTCONN;
	if (!inet) {
		/* Create an unconnected socket */
		if (!(sock = xprt_create_socket(xprt->prot, &xprt->timeout)))
			goto defer;
		xprt_bind_socket(xprt, sock);
		inet = sock->sk;
	}

	xprt_disconnect(xprt);

	/* Reset TCP record info */
	xprt->tcp_offset = 0;
	xprt->tcp_copied = 0;
	xprt->tcp_more = 0;

	/* Now connect it asynchronously. */
	dprintk("RPC: %4d connecting new socket\n", task->tk_pid);
	status = sock->ops->connect(sock, (struct sockaddr *) &xprt->addr,
				sizeof(xprt->addr), O_NONBLOCK);

	if (status < 0) {
		switch (status) {
		case -EALREADY:
		case -EINPROGRESS:
			status = 0;
			break;
		case -EISCONN:
		case -EPIPE:
			status = 0;
			xprt_close(xprt);
			goto defer;
		default:
			printk("RPC: TCP connect error %d!\n", -status);
			xprt_close(xprt);
			goto defer;
		}

		dprintk("RPC: %4d connect status %d connected %d\n",
				task->tk_pid, status, xprt_connected(xprt));

		spin_lock_bh(&xprt_sock_lock);
		if (!xprt_connected(xprt)) {
			task->tk_timeout = xprt->timeout.to_maxval;
			rpc_sleep_on(&xprt->reconn, task, xprt_reconn_status, NULL);
			spin_unlock_bh(&xprt_sock_lock);
			return;
		}
		spin_unlock_bh(&xprt_sock_lock);
	}
defer:
	spin_lock(&xprt_lock);
	xprt->connecting = 0;
	if (status < 0) {
		rpc_delay(task, 5*HZ);
		task->tk_status = -ENOTCONN;
	}
	rpc_wake_up(&xprt->reconn);
	spin_unlock(&xprt_lock);
}

/*
 * Reconnect timeout. We just mark the transport as not being in the
 * process of reconnecting, and leave the rest to the upper layers.
 */
static void
xprt_reconn_status(struct rpc_task *task)
{
	struct rpc_xprt	*xprt = task->tk_xprt;

	dprintk("RPC: %4d xprt_reconn_timeout %d\n",
				task->tk_pid, task->tk_status);

	spin_lock(&xprt_lock);
	xprt->connecting = 0;
	rpc_wake_up(&xprt->reconn);
	spin_unlock(&xprt_lock);
}

/*
 * Look up the RPC request corresponding to a reply, and then lock it.
 */
static inline struct rpc_rqst *
xprt_lookup_rqst(struct rpc_xprt *xprt, u32 xid)
{
	struct rpc_task	*head, *task;
	struct rpc_rqst	*req;
	int		safe = 0;

	spin_lock_bh(&rpc_queue_lock);
	if ((head = xprt->pending.task) != NULL) {
		task = head;
		do {
			if ((req = task->tk_rqstp) && req->rq_xid == xid)
				goto out;
			task = task->tk_next;
			if (++safe > 100) {
				printk("xprt_lookup_rqst: loop in Q!\n");
				goto out_bad;
			}
		} while (task != head);
	}
	dprintk("RPC:      unknown XID %08x in reply.\n", xid);
 out_bad:
	req = NULL;
 out:
	if (req && !__rpc_lock_task(req->rq_task))
		req = NULL;
	spin_unlock_bh(&rpc_queue_lock);
	return req;
}

/*
 * Complete reply received.
 * The TCP code relies on us to remove the request from xprt->pending.
 */
static inline void
xprt_complete_rqst(struct rpc_xprt *xprt, struct rpc_rqst *req, int copied)
{
	struct rpc_task	*task = req->rq_task;