Logo Search packages:      
Sourcecode: linux version File versions  Download package

lowcomms.c

/******************************************************************************
*******************************************************************************
**
**  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))
                        queue_work(recv_workqueue, &new_con->rwork);
            }
            break;

            case SCTP_COMM_LOST:
            case SCTP_SHUTDOWN_COMP:
            {
                  con = assoc2con(sn->sn_assoc_change.sac_assoc_id);
                  if (con) {
                        con->sctp_assoc = 0;
                  }
            }
            break;

            /* We don't know which INIT failed, so clear the PENDING flags
             * on them all.  if assoc_id is zero then it will then try
             * again */

            case SCTP_CANT_STR_ASSOC:
            {
                  log_print("Can't start SCTP association - retrying");
                  sctp_init_failed();
            }
            break;

            default:
                  log_print("unexpected SCTP assoc change id=%d state=%d",
                          (int)sn->sn_assoc_change.sac_assoc_id,
                          sn->sn_assoc_change.sac_state);
            }
      }
}

/* Data received from remote end */
static int receive_from_sock(struct connection *con)
{
      int ret = 0;
      struct msghdr msg = {};
      struct kvec iov[2];
      unsigned len;
      int r;
      int call_again_soon = 0;
      int nvec;
      char incmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];

      mutex_lock(&con->sock_mutex);

      if (con->sock == NULL) {
            ret = -EAGAIN;
            goto out_close;
      }

      if (con->rx_page == NULL) {
            /*
             * This doesn't need to be atomic, but I think it should
             * improve performance if it is.
             */
            con->rx_page = alloc_page(GFP_ATOMIC);
            if (con->rx_page == NULL)
                  goto out_resched;
            cbuf_init(&con->cb, PAGE_CACHE_SIZE);
      }

      /* Only SCTP needs these really */
      memset(&incmsg, 0, sizeof(incmsg));
      msg.msg_control = incmsg;
      msg.msg_controllen = sizeof(incmsg);

      /*
       * iov[0] is the bit of the circular buffer between the current end
       * point (cb.base + cb.len) and the end of the buffer.
       */
      iov[0].iov_len = con->cb.base - cbuf_data(&con->cb);
      iov[0].iov_base = page_address(con->rx_page) + cbuf_data(&con->cb);
      iov[1].iov_len = 0;
      nvec = 1;

      /*
       * iov[1] is the bit of the circular buffer between the start of the
       * buffer and the start of the currently used section (cb.base)
       */
      if (cbuf_data(&con->cb) >= con->cb.base) {
            iov[0].iov_len = PAGE_CACHE_SIZE - cbuf_data(&con->cb);
            iov[1].iov_len = con->cb.base;
            iov[1].iov_base = page_address(con->rx_page);
            nvec = 2;
      }
      len = iov[0].iov_len + iov[1].iov_len;

      r = ret = kernel_recvmsg(con->sock, &msg, iov, nvec, len,
                         MSG_DONTWAIT | MSG_NOSIGNAL);
      if (ret <= 0)
            goto out_close;

      /* Process SCTP notifications */
      if (msg.msg_flags & MSG_NOTIFICATION) {
            msg.msg_control = incmsg;
            msg.msg_controllen = sizeof(incmsg);

            process_sctp_notification(con, &msg,
                        page_address(con->rx_page) + con->cb.base);
            mutex_unlock(&con->sock_mutex);
            return 0;
      }
      BUG_ON(con->nodeid == 0);

      if (ret == len)
            call_again_soon = 1;
      cbuf_add(&con->cb, ret);
      ret = dlm_process_incoming_buffer(con->nodeid,
                                page_address(con->rx_page),
                                con->cb.base, con->cb.len,
                                PAGE_CACHE_SIZE);
      if (ret == -EBADMSG) {
            log_print("lowcomms: addr=%p, base=%u, len=%u, "
                    "iov_len=%u, iov_base[0]=%p, read=%d",
                    page_address(con->rx_page), con->cb.base, con->cb.len,
                    len, iov[0].iov_base, r);
      }
      if (ret < 0)
            goto out_close;
      cbuf_eat(&con->cb, ret);

      if (cbuf_empty(&con->cb) && !call_again_soon) {
            __free_page(con->rx_page);
            con->rx_page = NULL;
      }

      if (call_again_soon)
            goto out_resched;
      mutex_unlock(&con->sock_mutex);
      return 0;

out_resched:
      if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
            queue_work(recv_workqueue, &con->rwork);
      mutex_unlock(&con->sock_mutex);
      return -EAGAIN;

out_close:
      mutex_unlock(&con->sock_mutex);
      if (ret != -EAGAIN) {
            close_connection(con, false);
            /* Reconnect when there is something to send */
      }
      /* Don't return success if we really got EOF */
      if (ret == 0)
            ret = -EAGAIN;

      return ret;
}

/* Listening socket is busy, accept a connection */
static int tcp_accept_from_sock(struct connection *con)
{
      int result;
      struct sockaddr_storage peeraddr;
      struct socket *newsock;
      int len;
      int nodeid;
      struct connection *newcon;
      struct connection *addcon;

      memset(&peeraddr, 0, sizeof(peeraddr));
      result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
                          IPPROTO_TCP, &newsock);
      if (result < 0)
            return -ENOMEM;

      mutex_lock_nested(&con->sock_mutex, 0);

      result = -ENOTCONN;
      if (con->sock == NULL)
            goto accept_err;

      newsock->type = con->sock->type;
      newsock->ops = con->sock->ops;

      result = con->sock->ops->accept(con->sock, newsock, O_NONBLOCK);
      if (result < 0)
            goto accept_err;

      /* Get the connected socket's peer */
      memset(&peeraddr, 0, sizeof(peeraddr));
      if (newsock->ops->getname(newsock, (struct sockaddr *)&peeraddr,
                          &len, 2)) {
            result = -ECONNABORTED;
            goto accept_err;
      }

      /* Get the new node's NODEID */
      make_sockaddr(&peeraddr, 0, &len);
      if (dlm_addr_to_nodeid(&peeraddr, &nodeid)) {
            log_print("connect from non cluster node");
            sock_release(newsock);
            mutex_unlock(&con->sock_mutex);
            return -1;
      }

      log_print("got connection from %d", nodeid);

      /*  Check to see if we already have a connection to this node. This
       *  could happen if the two nodes initiate a connection at roughly
       *  the same time and the connections cross on the wire.
       *  In this case we store the incoming one in "othercon"
       */
      newcon = nodeid2con(nodeid, GFP_KERNEL);
      if (!newcon) {
            result = -ENOMEM;
            goto accept_err;
      }
      mutex_lock_nested(&newcon->sock_mutex, 1);
      if (newcon->sock) {
            struct connection *othercon = newcon->othercon;

            if (!othercon) {
                  othercon = kmem_cache_zalloc(con_cache, GFP_KERNEL);
                  if (!othercon) {
                        log_print("failed to allocate incoming socket");
                        mutex_unlock(&newcon->sock_mutex);
                        result = -ENOMEM;
                        goto accept_err;
                  }
                  othercon->nodeid = nodeid;
                  othercon->rx_action = receive_from_sock;
                  mutex_init(&othercon->sock_mutex);
                  INIT_WORK(&othercon->swork, process_send_sockets);
                  INIT_WORK(&othercon->rwork, process_recv_sockets);
                  set_bit(CF_IS_OTHERCON, &othercon->flags);
            }
            if (!othercon->sock) {
                  newcon->othercon = othercon;
                  othercon->sock = newsock;
                  newsock->sk->sk_user_data = othercon;
                  add_sock(newsock, othercon);
                  addcon = othercon;
            }
            else {
                  printk("Extra connection from node %d attempted\n", nodeid);
                  result = -EAGAIN;
                  mutex_unlock(&newcon->sock_mutex);
                  goto accept_err;
            }
      }
      else {
            newsock->sk->sk_user_data = newcon;
            newcon->rx_action = receive_from_sock;
            add_sock(newsock, newcon);
            addcon = newcon;
      }

      mutex_unlock(&newcon->sock_mutex);

      /*
       * Add it to the active queue in case we got data
       * beween processing the accept adding the socket
       * to the read_sockets list
       */
      if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
            queue_work(recv_workqueue, &addcon->rwork);
      mutex_unlock(&con->sock_mutex);

      return 0;

accept_err:
      mutex_unlock(&con->sock_mutex);
      sock_release(newsock);

      if (result != -EAGAIN)
            log_print("error accepting connection from node: %d", result);
      return result;
}

static void free_entry(struct writequeue_entry *e)
{
      __free_page(e->page);
      kfree(e);
}

/* Initiate an SCTP association.
   This is a special case of send_to_sock() in that we don't yet have a
   peeled-off socket for this association, so we use the listening socket
   and add the primary IP address of the remote node.
 */
static void sctp_init_assoc(struct connection *con)
{
      struct sockaddr_storage rem_addr;
      char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
      struct msghdr outmessage;
      struct cmsghdr *cmsg;
      struct sctp_sndrcvinfo *sinfo;
      struct connection *base_con;
      struct writequeue_entry *e;
      int len, offset;
      int ret;
      int addrlen;
      struct kvec iov[1];

      if (test_and_set_bit(CF_INIT_PENDING, &con->flags))
            return;

      if (con->retries++ > MAX_CONNECT_RETRIES)
            return;

      log_print("Initiating association with node %d", con->nodeid);

      if (nodeid_to_addr(con->nodeid, (struct sockaddr *)&rem_addr)) {
            log_print("no address for nodeid %d", con->nodeid);
            return;
      }
      base_con = nodeid2con(0, 0);
      BUG_ON(base_con == NULL);

      make_sockaddr(&rem_addr, dlm_config.ci_tcp_port, &addrlen);

      outmessage.msg_name = &rem_addr;
      outmessage.msg_namelen = addrlen;
      outmessage.msg_control = outcmsg;
      outmessage.msg_controllen = sizeof(outcmsg);
      outmessage.msg_flags = MSG_EOR;

      spin_lock(&con->writequeue_lock);
      e = list_entry(con->writequeue.next, struct writequeue_entry,
                   list);

      BUG_ON((struct list_head *) e == &con->writequeue);

      len = e->len;
      offset = e->offset;
      spin_unlock(&con->writequeue_lock);
      kmap(e->page);

      /* Send the first block off the write queue */
      iov[0].iov_base = page_address(e->page)+offset;
      iov[0].iov_len = len;

      cmsg = CMSG_FIRSTHDR(&outmessage);
      cmsg->cmsg_level = IPPROTO_SCTP;
      cmsg->cmsg_type = SCTP_SNDRCV;
      cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
      sinfo = CMSG_DATA(cmsg);
      memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
      sinfo->sinfo_ppid = cpu_to_le32(dlm_our_nodeid());
      outmessage.msg_controllen = cmsg->cmsg_len;

      ret = kernel_sendmsg(base_con->sock, &outmessage, iov, 1, len);
      if (ret < 0) {
            log_print("Send first packet to node %d failed: %d",
                    con->nodeid, ret);

            /* Try again later */
            clear_bit(CF_CONNECT_PENDING, &con->flags);
            clear_bit(CF_INIT_PENDING, &con->flags);
      }
      else {
            spin_lock(&con->writequeue_lock);
            e->offset += ret;
            e->len -= ret;

            if (e->len == 0 && e->users == 0) {
                  list_del(&e->list);
                  kunmap(e->page);
                  free_entry(e);
            }
            spin_unlock(&con->writequeue_lock);
      }
}

/* Connect a new socket to its peer */
static void tcp_connect_to_sock(struct connection *con)
{
      int result = -EHOSTUNREACH;
      struct sockaddr_storage saddr;
      int addr_len;
      struct socket *sock;

      if (con->nodeid == 0) {
            log_print("attempt to connect sock 0 foiled");
            return;
      }

      mutex_lock(&con->sock_mutex);
      if (con->retries++ > MAX_CONNECT_RETRIES)
            goto out;

      /* Some odd races can cause double-connects, ignore them */
      if (con->sock) {
            result = 0;
            goto out;
      }

      /* Create a socket to communicate with */
      result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
                          IPPROTO_TCP, &sock);
      if (result < 0)
            goto out_err;

      memset(&saddr, 0, sizeof(saddr));
      if (dlm_nodeid_to_addr(con->nodeid, &saddr))
            goto out_err;

      sock->sk->sk_user_data = con;
      con->rx_action = receive_from_sock;
      con->connect_action = tcp_connect_to_sock;
      add_sock(sock, con);

      make_sockaddr(&saddr, dlm_config.ci_tcp_port, &addr_len);

      log_print("connecting to %d", con->nodeid);
      result =
            sock->ops->connect(sock, (struct sockaddr *)&saddr, addr_len,
                           O_NONBLOCK);
      if (result == -EINPROGRESS)
            result = 0;
      if (result == 0)
            goto out;

out_err:
      if (con->sock) {
            sock_release(con->sock);
            con->sock = NULL;
      }
      /*
       * Some errors are fatal and this list might need adjusting. For other
       * errors we try again until the max number of retries is reached.
       */
      if (result != -EHOSTUNREACH && result != -ENETUNREACH &&
          result != -ENETDOWN && result != EINVAL
          && result != -EPROTONOSUPPORT) {
            lowcomms_connect_sock(con);
            result = 0;
      }
out:
      mutex_unlock(&con->sock_mutex);
      return;
}

static struct socket *tcp_create_listen_sock(struct connection *con,
                                   struct sockaddr_storage *saddr)
{
      struct socket *sock = NULL;
      int result = 0;
      int one = 1;
      int addr_len;

      if (dlm_local_addr[0]->ss_family == AF_INET)
            addr_len = sizeof(struct sockaddr_in);
      else
            addr_len = sizeof(struct sockaddr_in6);

      /* Create a socket to communicate with */
      result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
                          IPPROTO_TCP, &sock);
      if (result < 0) {
            log_print("Can't create listening comms socket");
            goto create_out;
      }

      result = kernel_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
                           (char *)&one, sizeof(one));

      if (result < 0) {
            log_print("Failed to set SO_REUSEADDR on socket: %d", result);
      }
      sock->sk->sk_user_data = con;
      con->rx_action = tcp_accept_from_sock;
      con->connect_action = tcp_connect_to_sock;
      con->sock = sock;

      /* Bind to our port */
      make_sockaddr(saddr, dlm_config.ci_tcp_port, &addr_len);
      result = sock->ops->bind(sock, (struct sockaddr *) saddr, addr_len);
      if (result < 0) {
            log_print("Can't bind to port %d", dlm_config.ci_tcp_port);
            sock_release(sock);
            sock = NULL;
            con->sock = NULL;
            goto create_out;
      }
      result = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
                         (char *)&one, sizeof(one));
      if (result < 0) {
            log_print("Set keepalive failed: %d", result);
      }

      result = sock->ops->listen(sock, 5);
      if (result < 0) {
            log_print("Can't listen on port %d", dlm_config.ci_tcp_port);
            sock_release(sock);
            sock = NULL;
            goto create_out;
      }

create_out:
      return sock;
}

/* Get local addresses */
static void init_local(void)
{
      struct sockaddr_storage sas, *addr;
      int i;

      dlm_local_count = 0;
      for (i = 0; i < DLM_MAX_ADDR_COUNT - 1; i++) {
            if (dlm_our_addr(&sas, i))
                  break;

            addr = kmalloc(sizeof(*addr), GFP_KERNEL);
            if (!addr)
                  break;
            memcpy(addr, &sas, sizeof(*addr));
            dlm_local_addr[dlm_local_count++] = addr;
      }
}

/* Bind to an IP address. SCTP allows multiple address so it can do
   multi-homing */
static int add_sctp_bind_addr(struct connection *sctp_con,
                        struct sockaddr_storage *addr,
                        int addr_len, int num)
{
      int result = 0;

      if (num == 1)
            result = kernel_bind(sctp_con->sock,
                             (struct sockaddr *) addr,
                             addr_len);
      else
            result = kernel_setsockopt(sctp_con->sock, SOL_SCTP,
                                 SCTP_SOCKOPT_BINDX_ADD,
                                 (char *)addr, addr_len);

      if (result < 0)
            log_print("Can't bind to port %d addr number %d",
                    dlm_config.ci_tcp_port, num);

      return result;
}

/* Initialise SCTP socket and bind to all interfaces */
static int sctp_listen_for_all(void)
{
      struct socket *sock = NULL;
      struct sockaddr_storage localaddr;
      struct sctp_event_subscribe subscribe;
      int result = -EINVAL, num = 1, i, addr_len;
      struct connection *con = nodeid2con(0, GFP_KERNEL);
      int bufsize = NEEDED_RMEM;

      if (!con)
            return -ENOMEM;

      log_print("Using SCTP for communications");

      result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_SEQPACKET,
                          IPPROTO_SCTP, &sock);
      if (result < 0) {
            log_print("Can't create comms socket, check SCTP is loaded");
            goto out;
      }

      /* Listen for events */
      memset(&subscribe, 0, sizeof(subscribe));
      subscribe.sctp_data_io_event = 1;
      subscribe.sctp_association_event = 1;
      subscribe.sctp_send_failure_event = 1;
      subscribe.sctp_shutdown_event = 1;
      subscribe.sctp_partial_delivery_event = 1;

      result = kernel_setsockopt(sock, SOL_SOCKET, SO_RCVBUFFORCE,
                         (char *)&bufsize, sizeof(bufsize));
      if (result)
            log_print("Error increasing buffer space on socket %d", result);

      result = kernel_setsockopt(sock, SOL_SCTP, SCTP_EVENTS,
                           (char *)&subscribe, sizeof(subscribe));
      if (result < 0) {
            log_print("Failed to set SCTP_EVENTS on socket: result=%d",
                    result);
            goto create_delsock;
      }

      /* Init con struct */
      sock->sk->sk_user_data = con;
      con->sock = sock;
      con->sock->sk->sk_data_ready = lowcomms_data_ready;
      con->rx_action = receive_from_sock;
      con->connect_action = sctp_init_assoc;

      /* Bind to all interfaces. */
      for (i = 0; i < dlm_local_count; i++) {
            memcpy(&localaddr, dlm_local_addr[i], sizeof(localaddr));
            make_sockaddr(&localaddr, dlm_config.ci_tcp_port, &addr_len);

            result = add_sctp_bind_addr(con, &localaddr, addr_len, num);
            if (result)
                  goto create_delsock;
            ++num;
      }

      result = sock->ops->listen(sock, 5);
      if (result < 0) {
            log_print("Can't set socket listening");
            goto create_delsock;
      }

      return 0;

create_delsock:
      sock_release(sock);
      con->sock = NULL;
out:
      return result;
}

static int tcp_listen_for_all(void)
{
      struct socket *sock = NULL;
      struct connection *con = nodeid2con(0, GFP_KERNEL);
      int result = -EINVAL;

      if (!con)
            return -ENOMEM;

      /* We don't support multi-homed hosts */
      if (dlm_local_addr[1] != NULL) {
            log_print("TCP protocol can't handle multi-homed hosts, "
                    "try SCTP");
            return -EINVAL;
      }

      log_print("Using TCP for communications");

      sock = tcp_create_listen_sock(con, dlm_local_addr[0]);
      if (sock) {
            add_sock(sock, con);
            result = 0;
      }
      else {
            result = -EADDRINUSE;
      }

      return result;
}



static struct writequeue_entry *new_writequeue_entry(struct connection *con,
                                         gfp_t allocation)
{
      struct writequeue_entry *entry;

      entry = kmalloc(sizeof(struct writequeue_entry), allocation);
      if (!entry)
            return NULL;

      entry->page = alloc_page(allocation);
      if (!entry->page) {
            kfree(entry);
            return NULL;
      }

      entry->offset = 0;
      entry->len = 0;
      entry->end = 0;
      entry->users = 0;
      entry->con = con;

      return entry;
}

void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
{
      struct connection *con;
      struct writequeue_entry *e;
      int offset = 0;
      int users = 0;

      con = nodeid2con(nodeid, allocation);
      if (!con)
            return NULL;

      spin_lock(&con->writequeue_lock);
      e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
      if ((&e->list == &con->writequeue) ||
          (PAGE_CACHE_SIZE - e->end < len)) {
            e = NULL;
      } else {
            offset = e->end;
            e->end += len;
            users = e->users++;
      }
      spin_unlock(&con->writequeue_lock);

      if (e) {
      got_one:
            if (users == 0)
                  kmap(e->page);
            *ppc = page_address(e->page) + offset;
            return e;
      }

      e = new_writequeue_entry(con, allocation);
      if (e) {
            spin_lock(&con->writequeue_lock);
            offset = e->end;
            e->end += len;
            users = e->users++;
            list_add_tail(&e->list, &con->writequeue);
            spin_unlock(&con->writequeue_lock);
            goto got_one;
      }
      return NULL;
}

void dlm_lowcomms_commit_buffer(void *mh)
{
      struct writequeue_entry *e = (struct writequeue_entry *)mh;
      struct connection *con = e->con;
      int users;

      spin_lock(&con->writequeue_lock);
      users = --e->users;
      if (users)
            goto out;
      e->len = e->end - e->offset;
      kunmap(e->page);
      spin_unlock(&con->writequeue_lock);

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

out:
      spin_unlock(&con->writequeue_lock);
      return;
}

/* Send a message */
static void send_to_sock(struct connection *con)
{
      int ret = 0;
      ssize_t(*sendpage) (struct socket *, struct page *, int, size_t, int);
      const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
      struct writequeue_entry *e;
      int len, offset;

      mutex_lock(&con->sock_mutex);
      if (con->sock == NULL)
            goto out_connect;

      sendpage = con->sock->ops->sendpage;

      spin_lock(&con->writequeue_lock);
      for (;;) {
            e = list_entry(con->writequeue.next, struct writequeue_entry,
                         list);
            if ((struct list_head *) e == &con->writequeue)
                  break;

            len = e->len;
            offset = e->offset;
            BUG_ON(len == 0 && e->users == 0);
            spin_unlock(&con->writequeue_lock);
            kmap(e->page);

            ret = 0;
            if (len) {
                  ret = sendpage(con->sock, e->page, offset, len,
                               msg_flags);
                  if (ret == -EAGAIN || ret == 0) {
                        cond_resched();
                        goto out;
                  }
                  if (ret <= 0)
                        goto send_error;
            }
                  /* Don't starve people filling buffers */
                  cond_resched();

            spin_lock(&con->writequeue_lock);
            e->offset += ret;
            e->len -= ret;

            if (e->len == 0 && e->users == 0) {
                  list_del(&e->list);
                  kunmap(e->page);
                  free_entry(e);
                  continue;
            }
      }
      spin_unlock(&con->writequeue_lock);
out:
      mutex_unlock(&con->sock_mutex);
      return;

send_error:
      mutex_unlock(&con->sock_mutex);
      close_connection(con, false);
      lowcomms_connect_sock(con);
      return;

out_connect:
      mutex_unlock(&con->sock_mutex);
      if (!test_bit(CF_INIT_PENDING, &con->flags))
            lowcomms_connect_sock(con);
      return;
}

static void clean_one_writequeue(struct connection *con)
{
      struct list_head *list;
      struct list_head *temp;

      spin_lock(&con->writequeue_lock);
      list_for_each_safe(list, temp, &con->writequeue) {
            struct writequeue_entry *e =
                  list_entry(list, struct writequeue_entry, list);
            list_del(&e->list);
            free_entry(e);
      }
      spin_unlock(&con->writequeue_lock);
}

/* Called from recovery when it knows that a node has
   left the cluster */
int dlm_lowcomms_close(int nodeid)
{
      struct connection *con;

      log_print("closing connection to node %d", nodeid);
      con = nodeid2con(nodeid, 0);
      if (con) {
            clean_one_writequeue(con);
            close_connection(con, true);
      }
      return 0;
}

/* Receive workqueue function */
static void process_recv_sockets(struct work_struct *work)
{
      struct connection *con = container_of(work, struct connection, rwork);
      int err;

      clear_bit(CF_READ_PENDING, &con->flags);
      do {
            err = con->rx_action(con);
      } while (!err);
}

/* Send workqueue function */
static void process_send_sockets(struct work_struct *work)
{
      struct connection *con = container_of(work, struct connection, swork);

      if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
            con->connect_action(con);
      }
      clear_bit(CF_WRITE_PENDING, &con->flags);
      send_to_sock(con);
}


/* Discard all entries on the write queues */
static void clean_writequeues(void)
{
      int nodeid;

      for (nodeid = 1; nodeid <= max_nodeid; nodeid++) {
            struct connection *con = __nodeid2con(nodeid, 0);

            if (con)
                  clean_one_writequeue(con);
      }
}

static void work_stop(void)
{
      destroy_workqueue(recv_workqueue);
      destroy_workqueue(send_workqueue);
}

static int work_start(void)
{
      int error;
      recv_workqueue = create_workqueue("dlm_recv");
      error = IS_ERR(recv_workqueue);
      if (error) {
            log_print("can't start dlm_recv %d", error);
            return error;
      }

      send_workqueue = create_singlethread_workqueue("dlm_send");
      error = IS_ERR(send_workqueue);
      if (error) {
            log_print("can't start dlm_send %d", error);
            destroy_workqueue(recv_workqueue);
            return error;
      }

      return 0;
}

void dlm_lowcomms_stop(void)
{
      int i;
      struct connection *con;

      /* Set all the flags to prevent any
         socket activity.
      */
      down(&connections_lock);
      for (i = 0; i <= max_nodeid; i++) {
            con = __nodeid2con(i, 0);
            if (con) {
                  con->flags |= 0x0F;
                  if (con->sock)
                        con->sock->sk->sk_user_data = NULL;
            }
      }
      up(&connections_lock);

      work_stop();

      down(&connections_lock);
      clean_writequeues();

      for (i = 0; i <= max_nodeid; i++) {
            con = __nodeid2con(i, 0);
            if (con) {
                  close_connection(con, true);
                  kmem_cache_free(con_cache, con);
            }
      }
      max_nodeid = 0;
      up(&connections_lock);
      kmem_cache_destroy(con_cache);
      idr_init(&connections_idr);
}

int dlm_lowcomms_start(void)
{
      int error = -EINVAL;
      struct connection *con;

      init_local();
      if (!dlm_local_count) {
            error = -ENOTCONN;
            log_print("no local IP address has been set");
            goto out;
      }

      error = -ENOMEM;
      con_cache = kmem_cache_create("dlm_conn", sizeof(struct connection),
                              __alignof__(struct connection), 0,
                              NULL);
      if (!con_cache)
            goto out;

      /* Start listening */
      if (dlm_config.ci_protocol == 0)
            error = tcp_listen_for_all();
      else
            error = sctp_listen_for_all();
      if (error)
            goto fail_unlisten;

      error = work_start();
      if (error)
            goto fail_unlisten;

      return 0;

fail_unlisten:
      con = nodeid2con(0,0);
      if (con) {
            close_connection(con, false);
            kmem_cache_free(con_cache, con);
      }
      kmem_cache_destroy(con_cache);

out:
      return error;
}

Generated by  Doxygen 1.6.0   Back to index