lowcomms.c

linux 内核源代码

/******************************************************************************
*******************************************************************************
**
**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
**  Copyright (C) 2004-2007 Red Hat, Inc.  All rights reserved.
**
**  This copyrighted material is made available to anyone wishing to use,
**  modify, copy, or redistribute it subject to the terms and conditions
**  of the GNU General Public License v.2.
**
*******************************************************************************
******************************************************************************/

/*
 * lowcomms.c
 *
 * This is the "low-level" comms layer.
 *
 * It is responsible for sending/receiving messages
 * from other nodes in the cluster.
 *
 * Cluster nodes are referred to by their nodeids. nodeids are
 * simply 32 bit numbers to the locking module - if they need to
 * be expanded for the cluster infrastructure then that is it's
 * responsibility. It is this layer's
 * responsibility to resolve these into IP address or
 * whatever it needs for inter-node communication.
 *
 * The comms level is two kernel threads that deal mainly with
 * the receiving of messages from other nodes and passing them
 * up to the mid-level comms layer (which understands the
 * message format) for execution by the locking core, and
 * a send thread which does all the setting up of connections
 * to remote nodes and the sending of data. Threads are not allowed
 * to send their own data because it may cause them to wait in times
 * of high load. Also, this way, the sending thread can collect together
 * messages bound for one node and send them in one block.
 *
 * lowcomms will choose to use wither TCP or SCTP as its transport layer
 * depending on the configuration variable 'protocol'. This should be set
 * to 0 (default) for TCP or 1 for SCTP. It shouldbe configured using a
 * cluster-wide mechanism as it must be the same on all nodes of the cluster
 * for the DLM to function.
 *
 */

#include <asm/ioctls.h>
#include <net/sock.h>
#include <net/tcp.h>
#include <linux/pagemap.h>
#include <linux/idr.h>
#include <linux/file.h>
#include <linux/sctp.h>
#include <net/sctp/user.h>

#include "dlm_internal.h"
#include "lowcomms.h"
#include "midcomms.h"
#include "config.h"

#define NEEDED_RMEM (4*1024*1024)

struct cbuf {
	unsigned int base;
	unsigned int len;
	unsigned int mask;
};

static void cbuf_add(struct cbuf *cb, int n)
{
	cb->len += n;
}

static int cbuf_data(struct cbuf *cb)
{
	return ((cb->base + cb->len) & cb->mask);
}

static void cbuf_init(struct cbuf *cb, int size)
{
	cb->base = cb->len = 0;
	cb->mask = size-1;
}

static void cbuf_eat(struct cbuf *cb, int n)
{
	cb->len  -= n;
	cb->base += n;
	cb->base &= cb->mask;
}

static bool cbuf_empty(struct cbuf *cb)
{
	return cb->len == 0;
}

struct connection {
	struct socket *sock;	/* NULL if not connected */
	uint32_t nodeid;	/* So we know who we are in the list */
	struct mutex sock_mutex;
	unsigned long flags;
#define CF_READ_PENDING 1
#define CF_WRITE_PENDING 2
#define CF_CONNECT_PENDING 3
#define CF_INIT_PENDING 4
#define CF_IS_OTHERCON 5
	struct list_head writequeue;  /* List of outgoing writequeue_entries */
	spinlock_t writequeue_lock;
	int (*rx_action) (struct connection *);	/* What to do when active */
	void (*connect_action) (struct connection *);	/* What to do to connect */
	struct page *rx_page;
	struct cbuf cb;
	int retries;
#define MAX_CONNECT_RETRIES 3
	int sctp_assoc;
	struct connection *othercon;
	struct work_struct rwork; /* Receive workqueue */
	struct work_struct swork; /* Send workqueue */
};
#define sock2con(x) ((struct connection *)(x)->sk_user_data)

/* An entry waiting to be sent */
struct writequeue_entry {
	struct list_head list;
	struct page *page;
	int offset;
	int len;
	int end;
	int users;
	struct connection *con;
};

static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
static int dlm_local_count;

/* Work queues */
static struct workqueue_struct *recv_workqueue;
static struct workqueue_struct *send_workqueue;

static DEFINE_IDR(connections_idr);
static DECLARE_MUTEX(connections_lock);
static int max_nodeid;
static struct kmem_cache *con_cache;

static void process_recv_sockets(struct work_struct *work);
static void process_send_sockets(struct work_struct *work);

/*
 * If 'allocation' is zero then we don't attempt to create a new
 * connection structure for this node.
 */
static struct connection *__nodeid2con(int nodeid, gfp_t alloc)
{
	struct connection *con = NULL;
	int r;
	int n;

	con = idr_find(&connections_idr, nodeid);
	if (con || !alloc)
		return con;

	r = idr_pre_get(&connections_idr, alloc);
	if (!r)
		return NULL;

	con = kmem_cache_zalloc(con_cache, alloc);
	if (!con)
		return NULL;

	r = idr_get_new_above(&connections_idr, con, nodeid, &n);
	if (r) {
		kmem_cache_free(con_cache, con);
		return NULL;
	}

	if (n != nodeid) {
		idr_remove(&connections_idr, n);
		kmem_cache_free(con_cache, con);
		return NULL;
	}

	con->nodeid = nodeid;
	mutex_init(&con->sock_mutex);
	INIT_LIST_HEAD(&con->writequeue);
	spin_lock_init(&con->writequeue_lock);
	INIT_WORK(&con->swork, process_send_sockets);
	INIT_WORK(&con->rwork, process_recv_sockets);

	/* Setup action pointers for child sockets */
	if (con->nodeid) {
		struct connection *zerocon = idr_find(&connections_idr, 0);

		con->connect_action = zerocon->connect_action;
		if (!con->rx_action)
			con->rx_action = zerocon->rx_action;
	}

	if (nodeid > max_nodeid)
		max_nodeid = nodeid;

	return con;
}

static struct connection *nodeid2con(int nodeid, gfp_t allocation)
{
	struct connection *con;

	down(&connections_lock);
	con = __nodeid2con(nodeid, allocation);
	up(&connections_lock);

	return con;
}

/* This is a bit drastic, but only called when things go wrong */
static struct connection *assoc2con(int assoc_id)
{
	int i;
	struct connection *con;

	down(&connections_lock);
	for (i=0; i<=max_nodeid; i++) {
		con = __nodeid2con(i, 0);
		if (con && con->sctp_assoc == assoc_id) {
			up(&connections_lock);
			return con;
		}
	}
	up(&connections_lock);
	return NULL;
}

static int nodeid_to_addr(int nodeid, struct sockaddr *retaddr)
{
	struct sockaddr_storage addr;
	int error;

	if (!dlm_local_count)
		return -1;

	error = dlm_nodeid_to_addr(nodeid, &addr);
	if (error)
		return error;

	if (dlm_local_addr[0]->ss_family == AF_INET) {
		struct sockaddr_in *in4  = (struct sockaddr_in *) &addr;
		struct sockaddr_in *ret4 = (struct sockaddr_in *) retaddr;
		ret4->sin_addr.s_addr = in4->sin_addr.s_addr;
	} else {
		struct sockaddr_in6 *in6  = (struct sockaddr_in6 *) &addr;
		struct sockaddr_in6 *ret6 = (struct sockaddr_in6 *) retaddr;
		memcpy(&ret6->sin6_addr, &in6->sin6_addr,
		       sizeof(in6->sin6_addr));
	}

	return 0;
}

/* Data available on socket or listen socket received a connect */
static void lowcomms_data_ready(struct sock *sk, int count_unused)
{
	struct connection *con = sock2con(sk);
	if (con && !test_and_set_bit(CF_READ_PENDING, &con->flags))
		queue_work(recv_workqueue, &con->rwork);
}

static void lowcomms_write_space(struct sock *sk)
{
	struct connection *con = sock2con(sk);

	if (con && !test_and_set_bit(CF_WRITE_PENDING, &con->flags))
		queue_work(send_workqueue, &con->swork);
}

static inline void lowcomms_connect_sock(struct connection *con)
{
	if (!test_and_set_bit(CF_CONNECT_PENDING, &con->flags))
		queue_work(send_workqueue, &con->swork);
}

static void lowcomms_state_change(struct sock *sk)
{
	if (sk->sk_state == TCP_ESTABLISHED)
		lowcomms_write_space(sk);
}

/* Make a socket active */
static int add_sock(struct socket *sock, struct connection *con)
{
	con->sock = sock;

	/* Install a data_ready callback */
	con->sock->sk->sk_data_ready = lowcomms_data_ready;
	con->sock->sk->sk_write_space = lowcomms_write_space;
	con->sock->sk->sk_state_change = lowcomms_state_change;
	con->sock->sk->sk_user_data = con;
	return 0;
}

/* Add the port number to an IPv6 or 4 sockaddr and return the address
   length */
static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
			  int *addr_len)
{
	saddr->ss_family =  dlm_local_addr[0]->ss_family;
	if (saddr->ss_family == AF_INET) {
		struct sockaddr_in *in4_addr = (struct sockaddr_in *)saddr;
		in4_addr->sin_port = cpu_to_be16(port);
		*addr_len = sizeof(struct sockaddr_in);
		memset(&in4_addr->sin_zero, 0, sizeof(in4_addr->sin_zero));
	} else {
		struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)saddr;
		in6_addr->sin6_port = cpu_to_be16(port);
		*addr_len = sizeof(struct sockaddr_in6);
	}
	memset((char *)saddr + *addr_len, 0, sizeof(struct sockaddr_storage) - *addr_len);
}

/* Close a remote connection and tidy up */
static void close_connection(struct connection *con, bool and_other)
{
	mutex_lock(&con->sock_mutex);

	if (con->sock) {
		sock_release(con->sock);
		con->sock = NULL;
	}
	if (con->othercon && and_other) {
		/* Will only re-enter once. */
		close_connection(con->othercon, false);
	}
	if (con->rx_page) {
		__free_page(con->rx_page);
		con->rx_page = NULL;
	}

	con->retries = 0;
	mutex_unlock(&con->sock_mutex);
}

/* We only send shutdown messages to nodes that are not part of the cluster */
static void sctp_send_shutdown(sctp_assoc_t associd)
{
	static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
	struct msghdr outmessage;
	struct cmsghdr *cmsg;
	struct sctp_sndrcvinfo *sinfo;
	int ret;
	struct connection *con;

	con = nodeid2con(0,0);
	BUG_ON(con == NULL);

	outmessage.msg_name = NULL;
	outmessage.msg_namelen = 0;
	outmessage.msg_control = outcmsg;
	outmessage.msg_controllen = sizeof(outcmsg);
	outmessage.msg_flags = MSG_EOR;

	cmsg = CMSG_FIRSTHDR(&outmessage);
	cmsg->cmsg_level = IPPROTO_SCTP;
	cmsg->cmsg_type = SCTP_SNDRCV;
	cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
	outmessage.msg_controllen = cmsg->cmsg_len;
	sinfo = CMSG_DATA(cmsg);
	memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));

	sinfo->sinfo_flags |= MSG_EOF;
	sinfo->sinfo_assoc_id = associd;

	ret = kernel_sendmsg(con->sock, &outmessage, NULL, 0, 0);

	if (ret != 0)
		log_print("send EOF to node failed: %d", ret);
}

/* INIT failed but we don't know which node...
   restart INIT on all pending nodes */
static void sctp_init_failed(void)
{
	int i;
	struct connection *con;

	down(&connections_lock);
	for (i=1; i<=max_nodeid; i++) {
		con = __nodeid2con(i, 0);
		if (!con)
			continue;
		con->sctp_assoc = 0;
		if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
			if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
				queue_work(send_workqueue, &con->swork);
			}
		}
	}
	up(&connections_lock);
}

/* Something happened to an association */
static void process_sctp_notification(struct connection *con,
				      struct msghdr *msg, char *buf)
{
	union sctp_notification *sn = (union sctp_notification *)buf;

	if (sn->sn_header.sn_type == SCTP_ASSOC_CHANGE) {
		switch (sn->sn_assoc_change.sac_state) {

		case SCTP_COMM_UP:
		case SCTP_RESTART:
		{
			/* Check that the new node is in the lockspace */
			struct sctp_prim prim;
			int nodeid;
			int prim_len, ret;
			int addr_len;
			struct connection *new_con;
			struct file *file;
			sctp_peeloff_arg_t parg;
			int parglen = sizeof(parg);

			/*
			 * We get this before any data for an association.
			 * We verify that the node is in the cluster and
			 * then peel off a socket for it.
			 */
			if ((int)sn->sn_assoc_change.sac_assoc_id <= 0) {
				log_print("COMM_UP for invalid assoc ID %d",
					 (int)sn->sn_assoc_change.sac_assoc_id);
				sctp_init_failed();
				return;
			}
			memset(&prim, 0, sizeof(struct sctp_prim));
			prim_len = sizeof(struct sctp_prim);
			prim.ssp_assoc_id = sn->sn_assoc_change.sac_assoc_id;

			ret = kernel_getsockopt(con->sock,
						IPPROTO_SCTP,
						SCTP_PRIMARY_ADDR,
						(char*)&prim,
						&prim_len);
			if (ret < 0) {
				log_print("getsockopt/sctp_primary_addr on "
					  "new assoc %d failed : %d",
					  (int)sn->sn_assoc_change.sac_assoc_id,
					  ret);

				/* Retry INIT later */
				new_con = assoc2con(sn->sn_assoc_change.sac_assoc_id);
				if (new_con)
					clear_bit(CF_CONNECT_PENDING, &con->flags);
				return;
			}
			make_sockaddr(&prim.ssp_addr, 0, &addr_len);
			if (dlm_addr_to_nodeid(&prim.ssp_addr, &nodeid)) {
				int i;
				unsigned char *b=(unsigned char *)&prim.ssp_addr;
				log_print("reject connect from unknown addr");
				for (i=0; i<sizeof(struct sockaddr_storage);i++)
					printk("%02x ", b[i]);
				printk("\n");
				sctp_send_shutdown(prim.ssp_assoc_id);
				return;
			}

			new_con = nodeid2con(nodeid, GFP_KERNEL);
			if (!new_con)
				return;

			/* Peel off a new sock */
			parg.associd = sn->sn_assoc_change.sac_assoc_id;
			ret = kernel_getsockopt(con->sock, IPPROTO_SCTP,
						SCTP_SOCKOPT_PEELOFF,
						(void *)&parg, &parglen);
			if (ret) {
				log_print("Can't peel off a socket for "
					  "connection %d to node %d: err=%d\n",
					  parg.associd, nodeid, ret);
			}
			file = fget(parg.sd);
			new_con->sock = SOCKET_I(file->f_dentry->d_inode);
			add_sock(new_con->sock, new_con);
			fput(file);
			put_unused_fd(parg.sd);

			log_print("got new/restarted association %d nodeid %d",
				 (int)sn->sn_assoc_change.sac_assoc_id, nodeid);

			/* Send any pending writes */
			clear_bit(CF_CONNECT_PENDING, &new_con->flags);
			clear_bit(CF_INIT_PENDING, &con->flags);
			if (!test_and_set_bit(CF_WRITE_PENDING, &new_con->flags)) {
				queue_work(send_workqueue, &new_con->swork);
			}
			if (!test_and_set_bit(CF_READ_PENDING, &new_con->flags))