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xprtsock.c

/*
 * linux/net/sunrpc/xprtsock.c
 *
 * Client-side transport implementation for sockets.
 *
 * TCP callback races fixes (C) 1998 Red Hat Software <alan@redhat.com>
 * TCP send fixes (C) 1998 Red Hat Software <alan@redhat.com>
 * TCP NFS related read + write fixes
 *  (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
 *
 * Rewrite of larges part of the code in order to stabilize TCP stuff.
 * Fix behaviour when socket buffer is full.
 *  (C) 1999 Trond Myklebust <trond.myklebust@fys.uio.no>
 *
 * IP socket transport implementation, (C) 2005 Chuck Lever <cel@netapp.com>
 *
 * IPv6 support contributed by Gilles Quillard, Bull Open Source, 2005.
 *   <gilles.quillard@bull.net>
 */

#include <linux/types.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/capability.h>
#include <linux/pagemap.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/tcp.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/sched.h>
#include <linux/sunrpc/xprtsock.h>
#include <linux/file.h>

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

/*
 * xprtsock tunables
 */
unsigned int xprt_udp_slot_table_entries = RPC_DEF_SLOT_TABLE;
unsigned int xprt_tcp_slot_table_entries = RPC_DEF_SLOT_TABLE;

unsigned int xprt_min_resvport = RPC_DEF_MIN_RESVPORT;
unsigned int xprt_max_resvport = RPC_DEF_MAX_RESVPORT;

/*
 * We can register our own files under /proc/sys/sunrpc by
 * calling register_sysctl_table() again.  The files in that
 * directory become the union of all files registered there.
 *
 * We simply need to make sure that we don't collide with
 * someone else's file names!
 */

#ifdef RPC_DEBUG

static unsigned int min_slot_table_size = RPC_MIN_SLOT_TABLE;
static unsigned int max_slot_table_size = RPC_MAX_SLOT_TABLE;
static unsigned int xprt_min_resvport_limit = RPC_MIN_RESVPORT;
static unsigned int xprt_max_resvport_limit = RPC_MAX_RESVPORT;

static struct ctl_table_header *sunrpc_table_header;

/*
 * FIXME: changing the UDP slot table size should also resize the UDP
 *        socket buffers for existing UDP transports
 */
static ctl_table xs_tunables_table[] = {
      {
            .ctl_name   = CTL_SLOTTABLE_UDP,
            .procname   = "udp_slot_table_entries",
            .data       = &xprt_udp_slot_table_entries,
            .maxlen           = sizeof(unsigned int),
            .mode       = 0644,
            .proc_handler     = &proc_dointvec_minmax,
            .strategy   = &sysctl_intvec,
            .extra1           = &min_slot_table_size,
            .extra2           = &max_slot_table_size
      },
      {
            .ctl_name   = CTL_SLOTTABLE_TCP,
            .procname   = "tcp_slot_table_entries",
            .data       = &xprt_tcp_slot_table_entries,
            .maxlen           = sizeof(unsigned int),
            .mode       = 0644,
            .proc_handler     = &proc_dointvec_minmax,
            .strategy   = &sysctl_intvec,
            .extra1           = &min_slot_table_size,
            .extra2           = &max_slot_table_size
      },
      {
            .ctl_name   = CTL_MIN_RESVPORT,
            .procname   = "min_resvport",
            .data       = &xprt_min_resvport,
            .maxlen           = sizeof(unsigned int),
            .mode       = 0644,
            .proc_handler     = &proc_dointvec_minmax,
            .strategy   = &sysctl_intvec,
            .extra1           = &xprt_min_resvport_limit,
            .extra2           = &xprt_max_resvport_limit
      },
      {
            .ctl_name   = CTL_MAX_RESVPORT,
            .procname   = "max_resvport",
            .data       = &xprt_max_resvport,
            .maxlen           = sizeof(unsigned int),
            .mode       = 0644,
            .proc_handler     = &proc_dointvec_minmax,
            .strategy   = &sysctl_intvec,
            .extra1           = &xprt_min_resvport_limit,
            .extra2           = &xprt_max_resvport_limit
      },
      {
            .ctl_name = 0,
      },
};

static ctl_table sunrpc_table[] = {
      {
            .ctl_name   = CTL_SUNRPC,
            .procname   = "sunrpc",
            .mode       = 0555,
            .child            = xs_tunables_table
      },
      {
            .ctl_name = 0,
      },
};

#endif

/*
 * How many times to try sending a request on a socket before waiting
 * for the socket buffer to clear.
 */
#define XS_SENDMSG_RETRY      (10U)

/*
 * Time out for an RPC UDP socket connect.  UDP socket connects are
 * synchronous, but we set a timeout anyway in case of resource
 * exhaustion on the local host.
 */
#define XS_UDP_CONN_TO        (5U * HZ)

/*
 * Wait duration for an RPC TCP connection to be established.  Solaris
 * NFS over TCP uses 60 seconds, for example, which is in line with how
 * long a server takes to reboot.
 */
#define XS_TCP_CONN_TO        (60U * HZ)

/*
 * Wait duration for a reply from the RPC portmapper.
 */
#define XS_BIND_TO            (60U * HZ)

/*
 * Delay if a UDP socket connect error occurs.  This is most likely some
 * kind of resource problem on the local host.
 */
#define XS_UDP_REEST_TO       (2U * HZ)

/*
 * The reestablish timeout allows clients to delay for a bit before attempting
 * to reconnect to a server that just dropped our connection.
 *
 * We implement an exponential backoff when trying to reestablish a TCP
 * transport connection with the server.  Some servers like to drop a TCP
 * connection when they are overworked, so we start with a short timeout and
 * increase over time if the server is down or not responding.
 */
#define XS_TCP_INIT_REEST_TO  (3U * HZ)
#define XS_TCP_MAX_REEST_TO   (5U * 60 * HZ)

/*
 * TCP idle timeout; client drops the transport socket if it is idle
 * for this long.  Note that we also timeout UDP sockets to prevent
 * holding port numbers when there is no RPC traffic.
 */
#define XS_IDLE_DISC_TO       (5U * 60 * HZ)

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

#ifdef RPC_DEBUG_DATA
static void xs_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 xs_pktdump(char *msg, u32 *packet, unsigned int count)
{
      /* NOP */
}
#endif

struct sock_xprt {
      struct rpc_xprt         xprt;

      /*
       * Network layer
       */
      struct socket *         sock;
      struct sock *           inet;

      /*
       * State of TCP reply receive
       */
      __be32                  tcp_fraghdr,
                        tcp_xid;

      u32               tcp_offset,
                        tcp_reclen;

      unsigned long           tcp_copied,
                        tcp_flags;

      /*
       * Connection of transports
       */
      struct delayed_work     connect_worker;
      struct sockaddr_storage addr;
      unsigned short          port;

      /*
       * UDP socket buffer size parameters
       */
      size_t                  rcvsize,
                        sndsize;

      /*
       * Saved socket callback addresses
       */
      void              (*old_data_ready)(struct sock *, int);
      void              (*old_state_change)(struct sock *);
      void              (*old_write_space)(struct sock *);
};

/*
 * TCP receive state flags
 */
#define TCP_RCV_LAST_FRAG     (1UL << 0)
#define TCP_RCV_COPY_FRAGHDR  (1UL << 1)
#define TCP_RCV_COPY_XID      (1UL << 2)
#define TCP_RCV_COPY_DATA     (1UL << 3)

static inline struct sockaddr *xs_addr(struct rpc_xprt *xprt)
{
      return (struct sockaddr *) &xprt->addr;
}

static inline struct sockaddr_in *xs_addr_in(struct rpc_xprt *xprt)
{
      return (struct sockaddr_in *) &xprt->addr;
}

static inline struct sockaddr_in6 *xs_addr_in6(struct rpc_xprt *xprt)
{
      return (struct sockaddr_in6 *) &xprt->addr;
}

static void xs_format_ipv4_peer_addresses(struct rpc_xprt *xprt)
{
      struct sockaddr_in *addr = xs_addr_in(xprt);
      char *buf;

      buf = kzalloc(20, GFP_KERNEL);
      if (buf) {
            snprintf(buf, 20, NIPQUAD_FMT,
                        NIPQUAD(addr->sin_addr.s_addr));
      }
      xprt->address_strings[RPC_DISPLAY_ADDR] = buf;

      buf = kzalloc(8, GFP_KERNEL);
      if (buf) {
            snprintf(buf, 8, "%u",
                        ntohs(addr->sin_port));
      }
      xprt->address_strings[RPC_DISPLAY_PORT] = buf;

      buf = kzalloc(8, GFP_KERNEL);
      if (buf) {
            if (xprt->prot == IPPROTO_UDP)
                  snprintf(buf, 8, "udp");
            else
                  snprintf(buf, 8, "tcp");
      }
      xprt->address_strings[RPC_DISPLAY_PROTO] = buf;

      buf = kzalloc(48, GFP_KERNEL);
      if (buf) {
            snprintf(buf, 48, "addr="NIPQUAD_FMT" port=%u proto=%s",
                  NIPQUAD(addr->sin_addr.s_addr),
                  ntohs(addr->sin_port),
                  xprt->prot == IPPROTO_UDP ? "udp" : "tcp");
      }
      xprt->address_strings[RPC_DISPLAY_ALL] = buf;

      buf = kzalloc(10, GFP_KERNEL);
      if (buf) {
            snprintf(buf, 10, "%02x%02x%02x%02x",
                        NIPQUAD(addr->sin_addr.s_addr));
      }
      xprt->address_strings[RPC_DISPLAY_HEX_ADDR] = buf;

      buf = kzalloc(8, GFP_KERNEL);
      if (buf) {
            snprintf(buf, 8, "%4hx",
                        ntohs(addr->sin_port));
      }
      xprt->address_strings[RPC_DISPLAY_HEX_PORT] = buf;

      buf = kzalloc(30, GFP_KERNEL);
      if (buf) {
            snprintf(buf, 30, NIPQUAD_FMT".%u.%u",
                        NIPQUAD(addr->sin_addr.s_addr),
                        ntohs(addr->sin_port) >> 8,
                        ntohs(addr->sin_port) & 0xff);
      }
      xprt->address_strings[RPC_DISPLAY_UNIVERSAL_ADDR] = buf;

      xprt->address_strings[RPC_DISPLAY_NETID] =
            kstrdup(xprt->prot == IPPROTO_UDP ?
                  RPCBIND_NETID_UDP : RPCBIND_NETID_TCP, GFP_KERNEL);
}

static void xs_format_ipv6_peer_addresses(struct rpc_xprt *xprt)
{
      struct sockaddr_in6 *addr = xs_addr_in6(xprt);
      char *buf;

      buf = kzalloc(40, GFP_KERNEL);
      if (buf) {
            snprintf(buf, 40, NIP6_FMT,
                        NIP6(addr->sin6_addr));
      }
      xprt->address_strings[RPC_DISPLAY_ADDR] = buf;

      buf = kzalloc(8, GFP_KERNEL);
      if (buf) {
            snprintf(buf, 8, "%u",
                        ntohs(addr->sin6_port));
      }
      xprt->address_strings[RPC_DISPLAY_PORT] = buf;

      buf = kzalloc(8, GFP_KERNEL);
      if (buf) {
            if (xprt->prot == IPPROTO_UDP)
                  snprintf(buf, 8, "udp");
            else
                  snprintf(buf, 8, "tcp");
      }
      xprt->address_strings[RPC_DISPLAY_PROTO] = buf;

      buf = kzalloc(64, GFP_KERNEL);
      if (buf) {
            snprintf(buf, 64, "addr="NIP6_FMT" port=%u proto=%s",
                        NIP6(addr->sin6_addr),
                        ntohs(addr->sin6_port),
                        xprt->prot == IPPROTO_UDP ? "udp" : "tcp");
      }
      xprt->address_strings[RPC_DISPLAY_ALL] = buf;

      buf = kzalloc(36, GFP_KERNEL);
      if (buf) {
            snprintf(buf, 36, NIP6_SEQFMT,
                        NIP6(addr->sin6_addr));
      }
      xprt->address_strings[RPC_DISPLAY_HEX_ADDR] = buf;

      buf = kzalloc(8, GFP_KERNEL);
      if (buf) {
            snprintf(buf, 8, "%4hx",
                        ntohs(addr->sin6_port));
      }
      xprt->address_strings[RPC_DISPLAY_HEX_PORT] = buf;

      buf = kzalloc(50, GFP_KERNEL);
      if (buf) {
            snprintf(buf, 50, NIP6_FMT".%u.%u",
                        NIP6(addr->sin6_addr),
                        ntohs(addr->sin6_port) >> 8,
                        ntohs(addr->sin6_port) & 0xff);
      }
      xprt->address_strings[RPC_DISPLAY_UNIVERSAL_ADDR] = buf;

      xprt->address_strings[RPC_DISPLAY_NETID] =
            kstrdup(xprt->prot == IPPROTO_UDP ?
                  RPCBIND_NETID_UDP6 : RPCBIND_NETID_TCP6, GFP_KERNEL);
}

static void xs_free_peer_addresses(struct rpc_xprt *xprt)
{
      int i;

      for (i = 0; i < RPC_DISPLAY_MAX; i++)
            kfree(xprt->address_strings[i]);
}

#define XS_SENDMSG_FLAGS      (MSG_DONTWAIT | MSG_NOSIGNAL)

static int xs_send_kvec(struct socket *sock, struct sockaddr *addr, int addrlen, struct kvec *vec, unsigned int base, int more)
{
      struct msghdr msg = {
            .msg_name   = addr,
            .msg_namelen      = addrlen,
            .msg_flags  = XS_SENDMSG_FLAGS | (more ? MSG_MORE : 0),
      };
      struct kvec iov = {
            .iov_base   = vec->iov_base + base,
            .iov_len    = vec->iov_len - base,
      };

      if (iov.iov_len != 0)
            return kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
      return kernel_sendmsg(sock, &msg, NULL, 0, 0);
}

static int xs_send_pagedata(struct socket *sock, struct xdr_buf *xdr, unsigned int base, int more)
{
      struct page **ppage;
      unsigned int remainder;
      int err, sent = 0;

      remainder = xdr->page_len - base;
      base += xdr->page_base;
      ppage = xdr->pages + (base >> PAGE_SHIFT);
      base &= ~PAGE_MASK;
      for(;;) {
            unsigned int len = min_t(unsigned int, PAGE_SIZE - base, remainder);
            int flags = XS_SENDMSG_FLAGS;

            remainder -= len;
            if (remainder != 0 || more)
                  flags |= MSG_MORE;
            err = sock->ops->sendpage(sock, *ppage, base, len, flags);
            if (remainder == 0 || err != len)
                  break;
            sent += err;
            ppage++;
            base = 0;
      }
      if (sent == 0)
            return err;
      if (err > 0)
            sent += err;
      return sent;
}

/**
 * xs_sendpages - write pages directly to a socket
 * @sock: socket to send on
 * @addr: UDP only -- address of destination
 * @addrlen: UDP only -- length of destination address
 * @xdr: buffer containing this request
 * @base: starting position in the buffer
 *
 */
static int xs_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen, struct xdr_buf *xdr, unsigned int base)
{
      unsigned int remainder = xdr->len - base;
      int err, sent = 0;

      if (unlikely(!sock))
            return -ENOTCONN;

      clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
      if (base != 0) {
            addr = NULL;
            addrlen = 0;
      }

      if (base < xdr->head[0].iov_len || addr != NULL) {
            unsigned int len = xdr->head[0].iov_len - base;
            remainder -= len;
            err = xs_send_kvec(sock, addr, addrlen, &xdr->head[0], base, remainder != 0);
            if (remainder == 0 || err != len)
                  goto out;
            sent += err;
            base = 0;
      } else
            base -= xdr->head[0].iov_len;

      if (base < xdr->page_len) {
            unsigned int len = xdr->page_len - base;
            remainder -= len;
            err = xs_send_pagedata(sock, xdr, base, remainder != 0);
            if (remainder == 0 || err != len)
                  goto out;
            sent += err;
            base = 0;
      } else
            base -= xdr->page_len;

      if (base >= xdr->tail[0].iov_len)
            return sent;
      err = xs_send_kvec(sock, NULL, 0, &xdr->tail[0], base, 0);
out:
      if (sent == 0)
            return err;
      if (err > 0)
            sent += err;
      return sent;
}

/**
 * xs_nospace - place task on wait queue if transmit was incomplete
 * @task: task to put to sleep
 *
 */
static void xs_nospace(struct rpc_task *task)
{
      struct rpc_rqst *req = task->tk_rqstp;
      struct rpc_xprt *xprt = req->rq_xprt;
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);

      dprintk("RPC: %5u xmit incomplete (%u left of %u)\n",
                  task->tk_pid, req->rq_slen - req->rq_bytes_sent,
                  req->rq_slen);

      if (test_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags)) {
            /* Protect against races with write_space */
            spin_lock_bh(&xprt->transport_lock);

            /* Don't race with disconnect */
            if (!xprt_connected(xprt))
                  task->tk_status = -ENOTCONN;
            else if (test_bit(SOCK_NOSPACE, &transport->sock->flags))
                  xprt_wait_for_buffer_space(task);

            spin_unlock_bh(&xprt->transport_lock);
      } else
            /* Keep holding the socket if it is blocked */
            rpc_delay(task, HZ>>4);
}

/**
 * xs_udp_send_request - write an RPC request to a UDP socket
 * @task: address of RPC task that manages the state of an RPC request
 *
 * Return values:
 *        0:      The request has been sent
 *   EAGAIN:      The socket was blocked, please call again later to
 *          complete the request
 * ENOTCONN:      Caller needs to invoke connect logic then call again
 *    other:      Some other error occured, the request was not sent
 */
static int xs_udp_send_request(struct rpc_task *task)
{
      struct rpc_rqst *req = task->tk_rqstp;
      struct rpc_xprt *xprt = req->rq_xprt;
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
      struct xdr_buf *xdr = &req->rq_snd_buf;
      int status;

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

      req->rq_xtime = jiffies;
      status = xs_sendpages(transport->sock,
                        xs_addr(xprt),
                        xprt->addrlen, xdr,
                        req->rq_bytes_sent);

      dprintk("RPC:       xs_udp_send_request(%u) = %d\n",
                  xdr->len - req->rq_bytes_sent, status);

      if (status >= 0) {
            task->tk_bytes_sent += status;
            if (status >= req->rq_slen)
                  return 0;
            /* Still some bytes left; set up for a retry later. */
            status = -EAGAIN;
      }

      switch (status) {
      case -ENETUNREACH:
      case -EPIPE:
      case -ECONNREFUSED:
            /* When the server has died, an ICMP port unreachable message
             * prompts ECONNREFUSED. */
            break;
      case -EAGAIN:
            xs_nospace(task);
            break;
      default:
            dprintk("RPC:       sendmsg returned unrecognized error %d\n",
                  -status);
            break;
      }

      return status;
}

static inline void xs_encode_tcp_record_marker(struct xdr_buf *buf)
{
      u32 reclen = buf->len - sizeof(rpc_fraghdr);
      rpc_fraghdr *base = buf->head[0].iov_base;
      *base = htonl(RPC_LAST_STREAM_FRAGMENT | reclen);
}

/**
 * xs_tcp_send_request - write an RPC request to a TCP socket
 * @task: address of RPC task that manages the state of an RPC request
 *
 * Return values:
 *        0:      The request has been sent
 *   EAGAIN:      The socket was blocked, please call again later to
 *          complete the request
 * ENOTCONN:      Caller needs to invoke connect logic then call again
 *    other:      Some other error occured, the request was not sent
 *
 * XXX: In the case of soft timeouts, should we eventually give up
 *    if sendmsg is not able to make progress?
 */
static int xs_tcp_send_request(struct rpc_task *task)
{
      struct rpc_rqst *req = task->tk_rqstp;
      struct rpc_xprt *xprt = req->rq_xprt;
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
      struct xdr_buf *xdr = &req->rq_snd_buf;
      int status;
      unsigned int retry = 0;

      xs_encode_tcp_record_marker(&req->rq_snd_buf);

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

      /* Continue transmitting the packet/record. We must be careful
       * to cope with writespace callbacks arriving _after_ we have
       * called sendmsg(). */
      while (1) {
            req->rq_xtime = jiffies;
            status = xs_sendpages(transport->sock,
                              NULL, 0, xdr, req->rq_bytes_sent);

            dprintk("RPC:       xs_tcp_send_request(%u) = %d\n",
                        xdr->len - req->rq_bytes_sent, status);

            if (unlikely(status < 0))
                  break;

            /* If we've sent the entire packet, immediately
             * reset the count of bytes sent. */
            req->rq_bytes_sent += status;
            task->tk_bytes_sent += status;
            if (likely(req->rq_bytes_sent >= req->rq_slen)) {
                  req->rq_bytes_sent = 0;
                  return 0;
            }

            status = -EAGAIN;
            if (retry++ > XS_SENDMSG_RETRY)
                  break;
      }

      switch (status) {
      case -EAGAIN:
            xs_nospace(task);
            break;
      case -ECONNREFUSED:
      case -ECONNRESET:
      case -ENOTCONN:
      case -EPIPE:
            status = -ENOTCONN;
            break;
      default:
            dprintk("RPC:       sendmsg returned unrecognized error %d\n",
                  -status);
            xprt_disconnect(xprt);
            break;
      }

      return status;
}

/**
 * xs_tcp_release_xprt - clean up after a tcp transmission
 * @xprt: transport
 * @task: rpc task
 *
 * This cleans up if an error causes us to abort the transmission of a request.
 * In this case, the socket may need to be reset in order to avoid confusing
 * the server.
 */
static void xs_tcp_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
{
      struct rpc_rqst *req;

      if (task != xprt->snd_task)
            return;
      if (task == NULL)
            goto out_release;
      req = task->tk_rqstp;
      if (req->rq_bytes_sent == 0)
            goto out_release;
      if (req->rq_bytes_sent == req->rq_snd_buf.len)
            goto out_release;
      set_bit(XPRT_CLOSE_WAIT, &task->tk_xprt->state);
out_release:
      xprt_release_xprt(xprt, task);
}

/**
 * xs_close - close a socket
 * @xprt: transport
 *
 * This is used when all requests are complete; ie, no DRC state remains
 * on the server we want to save.
 */
static void xs_close(struct rpc_xprt *xprt)
{
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
      struct socket *sock = transport->sock;
      struct sock *sk = transport->inet;

      if (!sk)
            goto clear_close_wait;

      dprintk("RPC:       xs_close xprt %p\n", xprt);

      write_lock_bh(&sk->sk_callback_lock);
      transport->inet = NULL;
      transport->sock = NULL;

      sk->sk_user_data = NULL;
      sk->sk_data_ready = transport->old_data_ready;
      sk->sk_state_change = transport->old_state_change;
      sk->sk_write_space = transport->old_write_space;
      write_unlock_bh(&sk->sk_callback_lock);

      sk->sk_no_check = 0;

      sock_release(sock);
clear_close_wait:
      smp_mb__before_clear_bit();
      clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
      smp_mb__after_clear_bit();
}

/**
 * xs_destroy - prepare to shutdown a transport
 * @xprt: doomed transport
 *
 */
static void xs_destroy(struct rpc_xprt *xprt)
{
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);

      dprintk("RPC:       xs_destroy xprt %p\n", xprt);

      cancel_rearming_delayed_work(&transport->connect_worker);

      xprt_disconnect(xprt);
      xs_close(xprt);
      xs_free_peer_addresses(xprt);
      kfree(xprt->slot);
      kfree(xprt);
      module_put(THIS_MODULE);
}

static inline struct rpc_xprt *xprt_from_sock(struct sock *sk)
{
      return (struct rpc_xprt *) sk->sk_user_data;
}

/**
 * xs_udp_data_ready - "data ready" callback for UDP sockets
 * @sk: socket with data to read
 * @len: how much data to read
 *
 */
static void xs_udp_data_ready(struct sock *sk, int len)
{
      struct rpc_task *task;
      struct rpc_xprt *xprt;
      struct rpc_rqst *rovr;
      struct sk_buff *skb;
      int err, repsize, copied;
      u32 _xid;
      __be32 *xp;

      read_lock(&sk->sk_callback_lock);
      dprintk("RPC:       xs_udp_data_ready...\n");
      if (!(xprt = xprt_from_sock(sk)))
            goto out;

      if ((skb = skb_recv_datagram(sk, 0, 1, &err)) == NULL)
            goto out;

      if (xprt->shutdown)
            goto dropit;

      repsize = skb->len - sizeof(struct udphdr);
      if (repsize < 4) {
            dprintk("RPC:       impossible RPC reply size %d!\n", repsize);
            goto dropit;
      }

      /* Copy the XID from the skb... */
      xp = skb_header_pointer(skb, sizeof(struct udphdr),
                        sizeof(_xid), &_xid);
      if (xp == NULL)
            goto dropit;

      /* Look up and lock the request corresponding to the given XID */
      spin_lock(&xprt->transport_lock);
      rovr = xprt_lookup_rqst(xprt, *xp);
      if (!rovr)
            goto out_unlock;
      task = rovr->rq_task;

      if ((copied = rovr->rq_private_buf.buflen) > repsize)
            copied = repsize;

      /* Suck it into the iovec, verify checksum if not done by hw. */
      if (csum_partial_copy_to_xdr(&rovr->rq_private_buf, skb))
            goto out_unlock;

      /* Something worked... */
      dst_confirm(skb->dst);

      xprt_adjust_cwnd(task, copied);
      xprt_update_rtt(task);
      xprt_complete_rqst(task, copied);

 out_unlock:
      spin_unlock(&xprt->transport_lock);
 dropit:
      skb_free_datagram(sk, skb);
 out:
      read_unlock(&sk->sk_callback_lock);
}

static inline void xs_tcp_read_fraghdr(struct rpc_xprt *xprt, struct xdr_skb_reader *desc)
{
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
      size_t len, used;
      char *p;

      p = ((char *) &transport->tcp_fraghdr) + transport->tcp_offset;
      len = sizeof(transport->tcp_fraghdr) - transport->tcp_offset;
      used = xdr_skb_read_bits(desc, p, len);
      transport->tcp_offset += used;
      if (used != len)
            return;

      transport->tcp_reclen = ntohl(transport->tcp_fraghdr);
      if (transport->tcp_reclen & RPC_LAST_STREAM_FRAGMENT)
            transport->tcp_flags |= TCP_RCV_LAST_FRAG;
      else
            transport->tcp_flags &= ~TCP_RCV_LAST_FRAG;
      transport->tcp_reclen &= RPC_FRAGMENT_SIZE_MASK;

      transport->tcp_flags &= ~TCP_RCV_COPY_FRAGHDR;
      transport->tcp_offset = 0;

      /* Sanity check of the record length */
      if (unlikely(transport->tcp_reclen < 4)) {
            dprintk("RPC:       invalid TCP record fragment length\n");
            xprt_disconnect(xprt);
            return;
      }
      dprintk("RPC:       reading TCP record fragment of length %d\n",
                  transport->tcp_reclen);
}

static void xs_tcp_check_fraghdr(struct sock_xprt *transport)
{
      if (transport->tcp_offset == transport->tcp_reclen) {
            transport->tcp_flags |= TCP_RCV_COPY_FRAGHDR;
            transport->tcp_offset = 0;
            if (transport->tcp_flags & TCP_RCV_LAST_FRAG) {
                  transport->tcp_flags &= ~TCP_RCV_COPY_DATA;
                  transport->tcp_flags |= TCP_RCV_COPY_XID;
                  transport->tcp_copied = 0;
            }
      }
}

static inline void xs_tcp_read_xid(struct sock_xprt *transport, struct xdr_skb_reader *desc)
{
      size_t len, used;
      char *p;

      len = sizeof(transport->tcp_xid) - transport->tcp_offset;
      dprintk("RPC:       reading XID (%Zu bytes)\n", len);
      p = ((char *) &transport->tcp_xid) + transport->tcp_offset;
      used = xdr_skb_read_bits(desc, p, len);
      transport->tcp_offset += used;
      if (used != len)
            return;
      transport->tcp_flags &= ~TCP_RCV_COPY_XID;
      transport->tcp_flags |= TCP_RCV_COPY_DATA;
      transport->tcp_copied = 4;
      dprintk("RPC:       reading reply for XID %08x\n",
                  ntohl(transport->tcp_xid));
      xs_tcp_check_fraghdr(transport);
}

static inline void xs_tcp_read_request(struct rpc_xprt *xprt, struct xdr_skb_reader *desc)
{
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
      struct rpc_rqst *req;
      struct xdr_buf *rcvbuf;
      size_t len;
      ssize_t r;

      /* Find and lock the request corresponding to this xid */
      spin_lock(&xprt->transport_lock);
      req = xprt_lookup_rqst(xprt, transport->tcp_xid);
      if (!req) {
            transport->tcp_flags &= ~TCP_RCV_COPY_DATA;
            dprintk("RPC:       XID %08x request not found!\n",
                        ntohl(transport->tcp_xid));
            spin_unlock(&xprt->transport_lock);
            return;
      }

      rcvbuf = &req->rq_private_buf;
      len = desc->count;
      if (len > transport->tcp_reclen - transport->tcp_offset) {
            struct xdr_skb_reader my_desc;

            len = transport->tcp_reclen - transport->tcp_offset;
            memcpy(&my_desc, desc, sizeof(my_desc));
            my_desc.count = len;
            r = xdr_partial_copy_from_skb(rcvbuf, transport->tcp_copied,
                                &my_desc, xdr_skb_read_bits);
            desc->count -= r;
            desc->offset += r;
      } else
            r = xdr_partial_copy_from_skb(rcvbuf, transport->tcp_copied,
                                desc, xdr_skb_read_bits);

      if (r > 0) {
            transport->tcp_copied += r;
            transport->tcp_offset += r;
      }
      if (r != len) {
            /* Error when copying to the receive buffer,
             * usually because we weren't able to allocate
             * additional buffer pages. All we can do now
             * is turn off TCP_RCV_COPY_DATA, so the request
             * will not receive any additional updates,
             * and time out.
             * Any remaining data from this record will
             * be discarded.
             */
            transport->tcp_flags &= ~TCP_RCV_COPY_DATA;
            dprintk("RPC:       XID %08x truncated request\n",
                        ntohl(transport->tcp_xid));
            dprintk("RPC:       xprt = %p, tcp_copied = %lu, "
                        "tcp_offset = %u, tcp_reclen = %u\n",
                        xprt, transport->tcp_copied,
                        transport->tcp_offset, transport->tcp_reclen);
            goto out;
      }

      dprintk("RPC:       XID %08x read %Zd bytes\n",
                  ntohl(transport->tcp_xid), r);
      dprintk("RPC:       xprt = %p, tcp_copied = %lu, tcp_offset = %u, "
                  "tcp_reclen = %u\n", xprt, transport->tcp_copied,
                  transport->tcp_offset, transport->tcp_reclen);

      if (transport->tcp_copied == req->rq_private_buf.buflen)
            transport->tcp_flags &= ~TCP_RCV_COPY_DATA;
      else if (transport->tcp_offset == transport->tcp_reclen) {
            if (transport->tcp_flags & TCP_RCV_LAST_FRAG)
                  transport->tcp_flags &= ~TCP_RCV_COPY_DATA;
      }

out:
      if (!(transport->tcp_flags & TCP_RCV_COPY_DATA))
            xprt_complete_rqst(req->rq_task, transport->tcp_copied);
      spin_unlock(&xprt->transport_lock);
      xs_tcp_check_fraghdr(transport);
}

static inline void xs_tcp_read_discard(struct sock_xprt *transport, struct xdr_skb_reader *desc)
{
      size_t len;

      len = transport->tcp_reclen - transport->tcp_offset;
      if (len > desc->count)
            len = desc->count;
      desc->count -= len;
      desc->offset += len;
      transport->tcp_offset += len;
      dprintk("RPC:       discarded %Zu bytes\n", len);
      xs_tcp_check_fraghdr(transport);
}

static int xs_tcp_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb, unsigned int offset, size_t len)
{
      struct rpc_xprt *xprt = rd_desc->arg.data;
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
      struct xdr_skb_reader desc = {
            .skb  = skb,
            .offset     = offset,
            .count      = len,
      };

      dprintk("RPC:       xs_tcp_data_recv started\n");
      do {
            /* Read in a new fragment marker if necessary */
            /* Can we ever really expect to get completely empty fragments? */
            if (transport->tcp_flags & TCP_RCV_COPY_FRAGHDR) {
                  xs_tcp_read_fraghdr(xprt, &desc);
                  continue;
            }
            /* Read in the xid if necessary */
            if (transport->tcp_flags & TCP_RCV_COPY_XID) {
                  xs_tcp_read_xid(transport, &desc);
                  continue;
            }
            /* Read in the request data */
            if (transport->tcp_flags & TCP_RCV_COPY_DATA) {
                  xs_tcp_read_request(xprt, &desc);
                  continue;
            }
            /* Skip over any trailing bytes on short reads */
            xs_tcp_read_discard(transport, &desc);
      } while (desc.count);
      dprintk("RPC:       xs_tcp_data_recv done\n");
      return len - desc.count;
}

/**
 * xs_tcp_data_ready - "data ready" callback for TCP sockets
 * @sk: socket with data to read
 * @bytes: how much data to read
 *
 */
static void xs_tcp_data_ready(struct sock *sk, int bytes)
{
      struct rpc_xprt *xprt;
      read_descriptor_t rd_desc;

      dprintk("RPC:       xs_tcp_data_ready...\n");

      read_lock(&sk->sk_callback_lock);
      if (!(xprt = xprt_from_sock(sk)))
            goto out;
      if (xprt->shutdown)
            goto out;

      /* We use rd_desc to pass struct xprt to xs_tcp_data_recv */
      rd_desc.arg.data = xprt;
      rd_desc.count = 65536;
      tcp_read_sock(sk, &rd_desc, xs_tcp_data_recv);
out:
      read_unlock(&sk->sk_callback_lock);
}

/**
 * xs_tcp_state_change - callback to handle TCP socket state changes
 * @sk: socket whose state has changed
 *
 */
static void xs_tcp_state_change(struct sock *sk)
{
      struct rpc_xprt *xprt;

      read_lock(&sk->sk_callback_lock);
      if (!(xprt = xprt_from_sock(sk)))
            goto out;
      dprintk("RPC:       xs_tcp_state_change client %p...\n", xprt);
      dprintk("RPC:       state %x conn %d dead %d zapped %d\n",
                  sk->sk_state, xprt_connected(xprt),
                  sock_flag(sk, SOCK_DEAD),
                  sock_flag(sk, SOCK_ZAPPED));

      switch (sk->sk_state) {
      case TCP_ESTABLISHED:
            spin_lock_bh(&xprt->transport_lock);
            if (!xprt_test_and_set_connected(xprt)) {
                  struct sock_xprt *transport = container_of(xprt,
                              struct sock_xprt, xprt);

                  /* Reset TCP record info */
                  transport->tcp_offset = 0;
                  transport->tcp_reclen = 0;
                  transport->tcp_copied = 0;
                  transport->tcp_flags =
                        TCP_RCV_COPY_FRAGHDR | TCP_RCV_COPY_XID;

                  xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
                  xprt_wake_pending_tasks(xprt, 0);
            }
            spin_unlock_bh(&xprt->transport_lock);
            break;
      case TCP_SYN_SENT:
      case TCP_SYN_RECV:
            break;
      case TCP_CLOSE_WAIT:
            /* Try to schedule an autoclose RPC calls */
            set_bit(XPRT_CLOSE_WAIT, &xprt->state);
            if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
                  queue_work(rpciod_workqueue, &xprt->task_cleanup);
      default:
            xprt_disconnect(xprt);
      }
 out:
      read_unlock(&sk->sk_callback_lock);
}

/**
 * xs_udp_write_space - callback invoked when socket buffer space
 *                             becomes available
 * @sk: socket whose state has changed
 *
 * Called when more output buffer space is available for this socket.
 * We try not to wake our writers until they can make "significant"
 * progress, otherwise we'll waste resources thrashing kernel_sendmsg
 * with a bunch of small requests.
 */
static void xs_udp_write_space(struct sock *sk)
{
      read_lock(&sk->sk_callback_lock);

      /* from net/core/sock.c:sock_def_write_space */
      if (sock_writeable(sk)) {
            struct socket *sock;
            struct rpc_xprt *xprt;

            if (unlikely(!(sock = sk->sk_socket)))
                  goto out;
            if (unlikely(!(xprt = xprt_from_sock(sk))))
                  goto out;
            if (unlikely(!test_and_clear_bit(SOCK_NOSPACE, &sock->flags)))
                  goto out;

            xprt_write_space(xprt);
      }

 out:
      read_unlock(&sk->sk_callback_lock);
}

/**
 * xs_tcp_write_space - callback invoked when socket buffer space
 *                             becomes available
 * @sk: socket whose state has changed
 *
 * Called when more output buffer space is available for this socket.
 * We try not to wake our writers until they can make "significant"
 * progress, otherwise we'll waste resources thrashing kernel_sendmsg
 * with a bunch of small requests.
 */
static void xs_tcp_write_space(struct sock *sk)
{
      read_lock(&sk->sk_callback_lock);

      /* from net/core/stream.c:sk_stream_write_space */
      if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
            struct socket *sock;
            struct rpc_xprt *xprt;

            if (unlikely(!(sock = sk->sk_socket)))
                  goto out;
            if (unlikely(!(xprt = xprt_from_sock(sk))))
                  goto out;
            if (unlikely(!test_and_clear_bit(SOCK_NOSPACE, &sock->flags)))
                  goto out;

            xprt_write_space(xprt);
      }

 out:
      read_unlock(&sk->sk_callback_lock);
}

static void xs_udp_do_set_buffer_size(struct rpc_xprt *xprt)
{
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
      struct sock *sk = transport->inet;

      if (transport->rcvsize) {
            sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
            sk->sk_rcvbuf = transport->rcvsize * xprt->max_reqs * 2;
      }
      if (transport->sndsize) {
            sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
            sk->sk_sndbuf = transport->sndsize * xprt->max_reqs * 2;
            sk->sk_write_space(sk);
      }
}

/**
 * xs_udp_set_buffer_size - set send and receive limits
 * @xprt: generic transport
 * @sndsize: requested size of send buffer, in bytes
 * @rcvsize: requested size of receive buffer, in bytes
 *
 * Set socket send and receive buffer size limits.
 */
static void xs_udp_set_buffer_size(struct rpc_xprt *xprt, size_t sndsize, size_t rcvsize)
{
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);

      transport->sndsize = 0;
      if (sndsize)
            transport->sndsize = sndsize + 1024;
      transport->rcvsize = 0;
      if (rcvsize)
            transport->rcvsize = rcvsize + 1024;

      xs_udp_do_set_buffer_size(xprt);
}

/**
 * xs_udp_timer - called when a retransmit timeout occurs on a UDP transport
 * @task: task that timed out
 *
 * Adjust the congestion window after a retransmit timeout has occurred.
 */
static void xs_udp_timer(struct rpc_task *task)
{
      xprt_adjust_cwnd(task, -ETIMEDOUT);
}

static unsigned short xs_get_random_port(void)
{
      unsigned short range = xprt_max_resvport - xprt_min_resvport;
      unsigned short rand = (unsigned short) net_random() % range;
      return rand + xprt_min_resvport;
}

/**
 * xs_set_port - reset the port number in the remote endpoint address
 * @xprt: generic transport
 * @port: new port number
 *
 */
static void xs_set_port(struct rpc_xprt *xprt, unsigned short port)
{
      struct sockaddr *addr = xs_addr(xprt);

      dprintk("RPC:       setting port for xprt %p to %u\n", xprt, port);

      switch (addr->sa_family) {
      case AF_INET:
            ((struct sockaddr_in *)addr)->sin_port = htons(port);
            break;
      case AF_INET6:
            ((struct sockaddr_in6 *)addr)->sin6_port = htons(port);
            break;
      default:
            BUG();
      }
}

static int xs_bind4(struct sock_xprt *transport, struct socket *sock)
{
      struct sockaddr_in myaddr = {
            .sin_family = AF_INET,
      };
      struct sockaddr_in *sa;
      int err;
      unsigned short port = transport->port;

      if (!transport->xprt.resvport)
            port = 0;
      sa = (struct sockaddr_in *)&transport->addr;
      myaddr.sin_addr = sa->sin_addr;
      do {
            myaddr.sin_port = htons(port);
            err = kernel_bind(sock, (struct sockaddr *) &myaddr,
                                    sizeof(myaddr));
            if (!transport->xprt.resvport)
                  break;
            if (err == 0) {
                  transport->port = port;
                  break;
            }
            if (port <= xprt_min_resvport)
                  port = xprt_max_resvport;
            else
                  port--;
      } while (err == -EADDRINUSE && port != transport->port);
      dprintk("RPC:       %s "NIPQUAD_FMT":%u: %s (%d)\n",
                  __FUNCTION__, NIPQUAD(myaddr.sin_addr),
                  port, err ? "failed" : "ok", err);
      return err;
}

static int xs_bind6(struct sock_xprt *transport, struct socket *sock)
{
      struct sockaddr_in6 myaddr = {
            .sin6_family = AF_INET6,
      };
      struct sockaddr_in6 *sa;
      int err;
      unsigned short port = transport->port;

      if (!transport->xprt.resvport)
            port = 0;
      sa = (struct sockaddr_in6 *)&transport->addr;
      myaddr.sin6_addr = sa->sin6_addr;
      do {
            myaddr.sin6_port = htons(port);
            err = kernel_bind(sock, (struct sockaddr *) &myaddr,
                                    sizeof(myaddr));
            if (!transport->xprt.resvport)
                  break;
            if (err == 0) {
                  transport->port = port;
                  break;
            }
            if (port <= xprt_min_resvport)
                  port = xprt_max_resvport;
            else
                  port--;
      } while (err == -EADDRINUSE && port != transport->port);
      dprintk("RPC:       xs_bind6 "NIP6_FMT":%u: %s (%d)\n",
            NIP6(myaddr.sin6_addr), port, err ? "failed" : "ok", err);
      return err;
}

#ifdef CONFIG_DEBUG_LOCK_ALLOC
static struct lock_class_key xs_key[2];
static struct lock_class_key xs_slock_key[2];

static inline void xs_reclassify_socket4(struct socket *sock)
{
      struct sock *sk = sock->sk;

      BUG_ON(sock_owned_by_user(sk));
      sock_lock_init_class_and_name(sk, "slock-AF_INET-RPC",
            &xs_slock_key[0], "sk_lock-AF_INET-RPC", &xs_key[0]);
}

static inline void xs_reclassify_socket6(struct socket *sock)
{
      struct sock *sk = sock->sk;

      BUG_ON(sock_owned_by_user(sk));
      sock_lock_init_class_and_name(sk, "slock-AF_INET6-RPC",
            &xs_slock_key[1], "sk_lock-AF_INET6-RPC", &xs_key[1]);
}
#else
static inline void xs_reclassify_socket4(struct socket *sock)
{
}

static inline void xs_reclassify_socket6(struct socket *sock)
{
}
#endif

static void xs_udp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
{
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);

      if (!transport->inet) {
            struct sock *sk = sock->sk;

            write_lock_bh(&sk->sk_callback_lock);

            sk->sk_user_data = xprt;
            transport->old_data_ready = sk->sk_data_ready;
            transport->old_state_change = sk->sk_state_change;
            transport->old_write_space = sk->sk_write_space;
            sk->sk_data_ready = xs_udp_data_ready;
            sk->sk_write_space = xs_udp_write_space;
            sk->sk_no_check = UDP_CSUM_NORCV;
            sk->sk_allocation = GFP_ATOMIC;

            xprt_set_connected(xprt);

            /* Reset to new socket */
            transport->sock = sock;
            transport->inet = sk;

            write_unlock_bh(&sk->sk_callback_lock);
      }
      xs_udp_do_set_buffer_size(xprt);
}

/**
 * xs_udp_connect_worker4 - set up a UDP socket
 * @work: RPC transport to connect
 *
 * Invoked by a work queue tasklet.
 */
static void xs_udp_connect_worker4(struct work_struct *work)
{
      struct sock_xprt *transport =
            container_of(work, struct sock_xprt, connect_worker.work);
      struct rpc_xprt *xprt = &transport->xprt;
      struct socket *sock = transport->sock;
      int err, status = -EIO;

      if (xprt->shutdown || !xprt_bound(xprt))
            goto out;

      /* Start by resetting any existing state */
      xs_close(xprt);

      if ((err = sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock)) < 0) {
            dprintk("RPC:       can't create UDP transport socket (%d).\n", -err);
            goto out;
      }
      xs_reclassify_socket4(sock);

      if (xs_bind4(transport, sock)) {
            sock_release(sock);
            goto out;
      }

      dprintk("RPC:       worker connecting xprt %p to address: %s\n",
                  xprt, xprt->address_strings[RPC_DISPLAY_ALL]);

      xs_udp_finish_connecting(xprt, sock);
      status = 0;
out:
      xprt_wake_pending_tasks(xprt, status);
      xprt_clear_connecting(xprt);
}

/**
 * xs_udp_connect_worker6 - set up a UDP socket
 * @work: RPC transport to connect
 *
 * Invoked by a work queue tasklet.
 */
static void xs_udp_connect_worker6(struct work_struct *work)
{
      struct sock_xprt *transport =
            container_of(work, struct sock_xprt, connect_worker.work);
      struct rpc_xprt *xprt = &transport->xprt;
      struct socket *sock = transport->sock;
      int err, status = -EIO;

      if (xprt->shutdown || !xprt_bound(xprt))
            goto out;

      /* Start by resetting any existing state */
      xs_close(xprt);

      if ((err = sock_create_kern(PF_INET6, SOCK_DGRAM, IPPROTO_UDP, &sock)) < 0) {
            dprintk("RPC:       can't create UDP transport socket (%d).\n", -err);
            goto out;
      }
      xs_reclassify_socket6(sock);

      if (xs_bind6(transport, sock) < 0) {
            sock_release(sock);
            goto out;
      }

      dprintk("RPC:       worker connecting xprt %p to address: %s\n",
                  xprt, xprt->address_strings[RPC_DISPLAY_ALL]);

      xs_udp_finish_connecting(xprt, sock);
      status = 0;
out:
      xprt_wake_pending_tasks(xprt, status);
      xprt_clear_connecting(xprt);
}

/*
 * We need to preserve the port number so the reply cache on the server can
 * find our cached RPC replies when we get around to reconnecting.
 */
static void xs_tcp_reuse_connection(struct rpc_xprt *xprt)
{
      int result;
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
      struct sockaddr any;

      dprintk("RPC:       disconnecting xprt %p to reuse port\n", xprt);

      /*
       * Disconnect the transport socket by doing a connect operation
       * with AF_UNSPEC.  This should return immediately...
       */
      memset(&any, 0, sizeof(any));
      any.sa_family = AF_UNSPEC;
      result = kernel_connect(transport->sock, &any, sizeof(any), 0);
      if (result)
            dprintk("RPC:       AF_UNSPEC connect return code %d\n",
                        result);
}

static int xs_tcp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
{
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);

      if (!transport->inet) {
            struct sock *sk = sock->sk;

            write_lock_bh(&sk->sk_callback_lock);

            sk->sk_user_data = xprt;
            transport->old_data_ready = sk->sk_data_ready;
            transport->old_state_change = sk->sk_state_change;
            transport->old_write_space = sk->sk_write_space;
            sk->sk_data_ready = xs_tcp_data_ready;
            sk->sk_state_change = xs_tcp_state_change;
            sk->sk_write_space = xs_tcp_write_space;
            sk->sk_allocation = GFP_ATOMIC;

            /* socket options */
            sk->sk_userlocks |= SOCK_BINDPORT_LOCK;
            sock_reset_flag(sk, SOCK_LINGER);
            tcp_sk(sk)->linger2 = 0;
            tcp_sk(sk)->nonagle |= TCP_NAGLE_OFF;

            xprt_clear_connected(xprt);

            /* Reset to new socket */
            transport->sock = sock;
            transport->inet = sk;

            write_unlock_bh(&sk->sk_callback_lock);
      }

      /* Tell the socket layer to start connecting... */
      xprt->stat.connect_count++;
      xprt->stat.connect_start = jiffies;
      return kernel_connect(sock, xs_addr(xprt), xprt->addrlen, O_NONBLOCK);
}

/**
 * xs_tcp_connect_worker4 - connect a TCP socket to a remote endpoint
 * @work: RPC transport to connect
 *
 * Invoked by a work queue tasklet.
 */
static void xs_tcp_connect_worker4(struct work_struct *work)
{
      struct sock_xprt *transport =
            container_of(work, struct sock_xprt, connect_worker.work);
      struct rpc_xprt *xprt = &transport->xprt;
      struct socket *sock = transport->sock;
      int err, status = -EIO;

      if (xprt->shutdown || !xprt_bound(xprt))
            goto out;

      if (!sock) {
            /* start from scratch */
            if ((err = sock_create_kern(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock)) < 0) {
                  dprintk("RPC:       can't create TCP transport socket (%d).\n", -err);
                  goto out;
            }
            xs_reclassify_socket4(sock);

            if (xs_bind4(transport, sock) < 0) {
                  sock_release(sock);
                  goto out;
            }
      } else
            /* "close" the socket, preserving the local port */
            xs_tcp_reuse_connection(xprt);

      dprintk("RPC:       worker connecting xprt %p to address: %s\n",
                  xprt, xprt->address_strings[RPC_DISPLAY_ALL]);

      status = xs_tcp_finish_connecting(xprt, sock);
      dprintk("RPC:       %p connect status %d connected %d sock state %d\n",
                  xprt, -status, xprt_connected(xprt),
                  sock->sk->sk_state);
      if (status < 0) {
            switch (status) {
                  case -EINPROGRESS:
                  case -EALREADY:
                        goto out_clear;
                  case -ECONNREFUSED:
                  case -ECONNRESET:
                        /* retry with existing socket, after a delay */
                        break;
                  default:
                        /* get rid of existing socket, and retry */
                        xs_close(xprt);
                        break;
            }
      }
out:
      xprt_wake_pending_tasks(xprt, status);
out_clear:
      xprt_clear_connecting(xprt);
}

/**
 * xs_tcp_connect_worker6 - connect a TCP socket to a remote endpoint
 * @work: RPC transport to connect
 *
 * Invoked by a work queue tasklet.
 */
static void xs_tcp_connect_worker6(struct work_struct *work)
{
      struct sock_xprt *transport =
            container_of(work, struct sock_xprt, connect_worker.work);
      struct rpc_xprt *xprt = &transport->xprt;
      struct socket *sock = transport->sock;
      int err, status = -EIO;

      if (xprt->shutdown || !xprt_bound(xprt))
            goto out;

      if (!sock) {
            /* start from scratch */
            if ((err = sock_create_kern(PF_INET6, SOCK_STREAM, IPPROTO_TCP, &sock)) < 0) {
                  dprintk("RPC:       can't create TCP transport socket (%d).\n", -err);
                  goto out;
            }
            xs_reclassify_socket6(sock);

            if (xs_bind6(transport, sock) < 0) {
                  sock_release(sock);
                  goto out;
            }
      } else
            /* "close" the socket, preserving the local port */
            xs_tcp_reuse_connection(xprt);

      dprintk("RPC:       worker connecting xprt %p to address: %s\n",
                  xprt, xprt->address_strings[RPC_DISPLAY_ALL]);

      status = xs_tcp_finish_connecting(xprt, sock);
      dprintk("RPC:       %p connect status %d connected %d sock state %d\n",
                  xprt, -status, xprt_connected(xprt), sock->sk->sk_state);
      if (status < 0) {
            switch (status) {
                  case -EINPROGRESS:
                  case -EALREADY:
                        goto out_clear;
                  case -ECONNREFUSED:
                  case -ECONNRESET:
                        /* retry with existing socket, after a delay */
                        break;
                  default:
                        /* get rid of existing socket, and retry */
                        xs_close(xprt);
                        break;
            }
      }
out:
      xprt_wake_pending_tasks(xprt, status);
out_clear:
      xprt_clear_connecting(xprt);
}

/**
 * xs_connect - connect a socket to a remote endpoint
 * @task: address of RPC task that manages state of connect request
 *
 * TCP: If the remote end dropped the connection, delay reconnecting.
 *
 * UDP socket connects are synchronous, but we use a work queue anyway
 * to guarantee that even unprivileged user processes can set up a
 * socket on a privileged port.
 *
 * If a UDP socket connect fails, the delay behavior here prevents
 * retry floods (hard mounts).
 */
static void xs_connect(struct rpc_task *task)
{
      struct rpc_xprt *xprt = task->tk_xprt;
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);

      if (xprt_test_and_set_connecting(xprt))
            return;

      if (transport->sock != NULL) {
            dprintk("RPC:       xs_connect delayed xprt %p for %lu "
                        "seconds\n",
                        xprt, xprt->reestablish_timeout / HZ);
            queue_delayed_work(rpciod_workqueue,
                           &transport->connect_worker,
                           xprt->reestablish_timeout);
            xprt->reestablish_timeout <<= 1;
            if (xprt->reestablish_timeout > XS_TCP_MAX_REEST_TO)
                  xprt->reestablish_timeout = XS_TCP_MAX_REEST_TO;
      } else {
            dprintk("RPC:       xs_connect scheduled xprt %p\n", xprt);
            queue_delayed_work(rpciod_workqueue,
                           &transport->connect_worker, 0);
      }
}

/**
 * xs_udp_print_stats - display UDP socket-specifc stats
 * @xprt: rpc_xprt struct containing statistics
 * @seq: output file
 *
 */
static void xs_udp_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
{
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);

      seq_printf(seq, "\txprt:\tudp %u %lu %lu %lu %lu %Lu %Lu\n",
                  transport->port,
                  xprt->stat.bind_count,
                  xprt->stat.sends,
                  xprt->stat.recvs,
                  xprt->stat.bad_xids,
                  xprt->stat.req_u,
                  xprt->stat.bklog_u);
}

/**
 * xs_tcp_print_stats - display TCP socket-specifc stats
 * @xprt: rpc_xprt struct containing statistics
 * @seq: output file
 *
 */
static void xs_tcp_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
{
      struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
      long idle_time = 0;

      if (xprt_connected(xprt))
            idle_time = (long)(jiffies - xprt->last_used) / HZ;

      seq_printf(seq, "\txprt:\ttcp %u %lu %lu %lu %ld %lu %lu %lu %Lu %Lu\n",
                  transport->port,
                  xprt->stat.bind_count,
                  xprt->stat.connect_count,
                  xprt->stat.connect_time,
                  idle_time,
                  xprt->stat.sends,
                  xprt->stat.recvs,
                  xprt->stat.bad_xids,
                  xprt->stat.req_u,
                  xprt->stat.bklog_u);
}

static struct rpc_xprt_ops xs_udp_ops = {
      .set_buffer_size  = xs_udp_set_buffer_size,
      .reserve_xprt           = xprt_reserve_xprt_cong,
      .release_xprt           = xprt_release_xprt_cong,
      .rpcbind          = rpcb_getport_async,
      .set_port         = xs_set_port,
      .connect          = xs_connect,
      .buf_alloc        = rpc_malloc,
      .buf_free         = rpc_free,
      .send_request           = xs_udp_send_request,
      .set_retrans_timeout    = xprt_set_retrans_timeout_rtt,
      .timer                  = xs_udp_timer,
      .release_request  = xprt_release_rqst_cong,
      .close                  = xs_close,
      .destroy          = xs_destroy,
      .print_stats            = xs_udp_print_stats,
};

static struct rpc_xprt_ops xs_tcp_ops = {
      .reserve_xprt           = xprt_reserve_xprt,
      .release_xprt           = xs_tcp_release_xprt,
      .rpcbind          = rpcb_getport_async,
      .set_port         = xs_set_port,
      .connect          = xs_connect,
      .buf_alloc        = rpc_malloc,
      .buf_free         = rpc_free,
      .send_request           = xs_tcp_send_request,
      .set_retrans_timeout    = xprt_set_retrans_timeout_def,
      .close                  = xs_close,
      .destroy          = xs_destroy,
      .print_stats            = xs_tcp_print_stats,
};

static struct rpc_xprt *xs_setup_xprt(struct xprt_create *args,
                              unsigned int slot_table_size)
{
      struct rpc_xprt *xprt;
      struct sock_xprt *new;

      if (args->addrlen > sizeof(xprt->addr)) {
            dprintk("RPC:       xs_setup_xprt: address too large\n");
            return ERR_PTR(-EBADF);
      }

      new = kzalloc(sizeof(*new), GFP_KERNEL);
      if (new == NULL) {
            dprintk("RPC:       xs_setup_xprt: couldn't allocate "
                        "rpc_xprt\n");
            return ERR_PTR(-ENOMEM);
      }
      xprt = &new->xprt;

      xprt->max_reqs = slot_table_size;
      xprt->slot = kcalloc(xprt->max_reqs, sizeof(struct rpc_rqst), GFP_KERNEL);
      if (xprt->slot == NULL) {
            kfree(xprt);
            dprintk("RPC:       xs_setup_xprt: couldn't allocate slot "
                        "table\n");
            return ERR_PTR(-ENOMEM);
      }

      memcpy(&xprt->addr, args->dstaddr, args->addrlen);
      xprt->addrlen = args->addrlen;
      if (args->srcaddr)
            memcpy(&new->addr, args->srcaddr, args->addrlen);
      new->port = xs_get_random_port();

      return xprt;
}

/**
 * xs_setup_udp - Set up transport to use a UDP socket
 * @args: rpc transport creation arguments
 *
 */
static struct rpc_xprt *xs_setup_udp(struct xprt_create *args)
{
      struct sockaddr *addr = args->dstaddr;
      struct rpc_xprt *xprt;
      struct sock_xprt *transport;

      xprt = xs_setup_xprt(args, xprt_udp_slot_table_entries);
      if (IS_ERR(xprt))
            return xprt;
      transport = container_of(xprt, struct sock_xprt, xprt);

      xprt->prot = IPPROTO_UDP;
      xprt->tsh_size = 0;
      /* XXX: header size can vary due to auth type, IPv6, etc. */
      xprt->max_payload = (1U << 16) - (MAX_HEADER << 3);

      xprt->bind_timeout = XS_BIND_TO;
      xprt->connect_timeout = XS_UDP_CONN_TO;
      xprt->reestablish_timeout = XS_UDP_REEST_TO;
      xprt->idle_timeout = XS_IDLE_DISC_TO;

      xprt->ops = &xs_udp_ops;

      if (args->timeout)
            xprt->timeout = *args->timeout;
      else
            xprt_set_timeout(&xprt->timeout, 5, 5 * HZ);

      switch (addr->sa_family) {
      case AF_INET:
            if (((struct sockaddr_in *)addr)->sin_port != htons(0))
                  xprt_set_bound(xprt);

            INIT_DELAYED_WORK(&transport->connect_worker,
                              xs_udp_connect_worker4);
            xs_format_ipv4_peer_addresses(xprt);
            break;
      case AF_INET6:
            if (((struct sockaddr_in6 *)addr)->sin6_port != htons(0))
                  xprt_set_bound(xprt);

            INIT_DELAYED_WORK(&transport->connect_worker,
                              xs_udp_connect_worker6);
            xs_format_ipv6_peer_addresses(xprt);
            break;
      default:
            kfree(xprt);
            return ERR_PTR(-EAFNOSUPPORT);
      }

      dprintk("RPC:       set up transport to address %s\n",
                  xprt->address_strings[RPC_DISPLAY_ALL]);

      if (try_module_get(THIS_MODULE))
            return xprt;

      kfree(xprt->slot);
      kfree(xprt);
      return ERR_PTR(-EINVAL);
}

/**
 * xs_setup_tcp - Set up transport to use a TCP socket
 * @args: rpc transport creation arguments
 *
 */
static struct rpc_xprt *xs_setup_tcp(struct xprt_create *args)
{
      struct sockaddr *addr = args->dstaddr;
      struct rpc_xprt *xprt;
      struct sock_xprt *transport;

      xprt = xs_setup_xprt(args, xprt_tcp_slot_table_entries);
      if (IS_ERR(xprt))
            return xprt;
      transport = container_of(xprt, struct sock_xprt, xprt);

      xprt->prot = IPPROTO_TCP;
      xprt->tsh_size = sizeof(rpc_fraghdr) / sizeof(u32);
      xprt->max_payload = RPC_MAX_FRAGMENT_SIZE;

      xprt->bind_timeout = XS_BIND_TO;
      xprt->connect_timeout = XS_TCP_CONN_TO;
      xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
      xprt->idle_timeout = XS_IDLE_DISC_TO;

      xprt->ops = &xs_tcp_ops;

      if (args->timeout)
            xprt->timeout = *args->timeout;
      else
            xprt_set_timeout(&xprt->timeout, 2, 60 * HZ);

      switch (addr->sa_family) {
      case AF_INET:
            if (((struct sockaddr_in *)addr)->sin_port != htons(0))
                  xprt_set_bound(xprt);

            INIT_DELAYED_WORK(&transport->connect_worker, xs_tcp_connect_worker4);
            xs_format_ipv4_peer_addresses(xprt);
            break;
      case AF_INET6:
            if (((struct sockaddr_in6 *)addr)->sin6_port != htons(0))
                  xprt_set_bound(xprt);

            INIT_DELAYED_WORK(&transport->connect_worker, xs_tcp_connect_worker6);
            xs_format_ipv6_peer_addresses(xprt);
            break;
      default:
            kfree(xprt);
            return ERR_PTR(-EAFNOSUPPORT);
      }

      dprintk("RPC:       set up transport to address %s\n",
                  xprt->address_strings[RPC_DISPLAY_ALL]);

      if (try_module_get(THIS_MODULE))
            return xprt;

      kfree(xprt->slot);
      kfree(xprt);
      return ERR_PTR(-EINVAL);
}

static struct xprt_class      xs_udp_transport = {
      .list       = LIST_HEAD_INIT(xs_udp_transport.list),
      .name       = "udp",
      .owner            = THIS_MODULE,
      .ident            = IPPROTO_UDP,
      .setup            = xs_setup_udp,
};

static struct xprt_class      xs_tcp_transport = {
      .list       = LIST_HEAD_INIT(xs_tcp_transport.list),
      .name       = "tcp",
      .owner            = THIS_MODULE,
      .ident            = IPPROTO_TCP,
      .setup            = xs_setup_tcp,
};

/**
 * init_socket_xprt - set up xprtsock's sysctls, register with RPC client
 *
 */
int init_socket_xprt(void)
{
#ifdef RPC_DEBUG
      if (!sunrpc_table_header)
            sunrpc_table_header = register_sysctl_table(sunrpc_table);
#endif

      xprt_register_transport(&xs_udp_transport);
      xprt_register_transport(&xs_tcp_transport);

      return 0;
}

/**
 * cleanup_socket_xprt - remove xprtsock's sysctls, unregister
 *
 */
void cleanup_socket_xprt(void)
{
#ifdef RPC_DEBUG
      if (sunrpc_table_header) {
            unregister_sysctl_table(sunrpc_table_header);
            sunrpc_table_header = NULL;
      }
#endif

      xprt_unregister_transport(&xs_udp_transport);
      xprt_unregister_transport(&xs_tcp_transport);
}

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