/*
 * linux/net/sunrpc/xprtsock.c
 *
 * Client-side transport implementation for sockets.
 *
 * TCP callback races fixes (C) 1998 Red Hat
 * TCP send fixes (C) 1998 Red Hat
 * 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;

#define XS_TCP_LINGER_TO        (15U * HZ)
static unsigned int xs_tcp_fin_timeout __read_mostly = XS_TCP_LINGER_TO;

/*
 * 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
        },
        {
                .procname       = "tcp_fin_timeout",
                .data           = &xs_tcp_fin_timeout,
                .maxlen         = sizeof(xs_tcp_fin_timeout),
                .mode           = 0644,
                .proc_handler   = &proc_dointvec_jiffies,
                .strategy       = sysctl_jiffies
        },
        {
                .ctl_name = 0,
        },
};

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

#endif

/*
 * 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 *);
        void                    (*old_error_report)(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,
                                          const char *protocol,
                                          const char *netid)
{
        struct sockaddr_in *addr = xs_addr_in(xprt);
        char *buf;

        buf = kzalloc(20, GFP_KERNEL);
        if (buf) {
                snprintf(buf, 20, "%pI4", &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;

        xprt->address_strings[RPC_DISPLAY_PROTO] = protocol;

        buf = kzalloc(48, GFP_KERNEL);
        if (buf) {
                snprintf(buf, 48, "addr=%pI4 port=%u proto=%s",
                        &addr->sin_addr.s_addr,
                        ntohs(addr->sin_port),
                        protocol);
        }
        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, "%pI4.%u.%u",
                                &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] = netid;
}

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

        buf = kzalloc(40, GFP_KERNEL);
        if (buf) {
                snprintf(buf, 40, "%pI6",&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;

        xprt->address_strings[RPC_DISPLAY_PROTO] = protocol;

        buf = kzalloc(64, GFP_KERNEL);
        if (buf) {
                snprintf(buf, 64, "addr=%pI6 port=%u proto=%s",
                                &addr->sin6_addr,
                                ntohs(addr->sin6_port),
                                protocol);
        }
        xprt->address_strings[RPC_DISPLAY_ALL] = buf;

        buf = kzalloc(36, GFP_KERNEL);
        if (buf)
                snprintf(buf, 36, "%pi6", &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, "%pI6.%u.%u",
                         &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] = netid;
}

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

        for (i = 0; i < RPC_DISPLAY_MAX; i++)
                switch (i) {
                case RPC_DISPLAY_PROTO:
                case RPC_DISPLAY_NETID:
                        continue;
                default:
                        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 -ENOTSOCK;

        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;
}

static void xs_nospace_callback(struct rpc_task *task)
{
        struct sock_xprt *transport = container_of(task->tk_rqstp->rq_xprt, struct sock_xprt, xprt);

        transport->inet->sk_write_pending--;
        clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
}

/**
 * xs_nospace - place task on wait queue if transmit was incomplete
 * @task: task to put to sleep
 *
 */
static int 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);
        int ret = 0;

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

        /* Protect against races with write_space */
        spin_lock_bh(&xprt->transport_lock);

        /* Don't race with disconnect */
        if (xprt_connected(xprt)) {
                if (test_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags)) {
                        ret = -EAGAIN;
                        /*
                         * Notify TCP that we're limited by the application
                         * window size
                         */
                        set_bit(SOCK_NOSPACE, &transport->sock->flags);
                        transport->inet->sk_write_pending++;
                        /* ...and wait for more buffer space */
                        xprt_wait_for_buffer_space(task, xs_nospace_callback);
                }
        } else {
                clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
                ret = -ENOTCONN;
        }

        spin_unlock_bh(&xprt->transport_lock);
        return ret;
}

/**
 * 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);

        if (!xprt_bound(xprt))
                return -ENOTCONN;
        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;
        }
        if (!transport->sock)
                goto out;

        switch (status) {
        case -ENOTSOCK:
                status = -ENOTCONN;
                /* Should we call xs_close() here? */
                break;
        case -EAGAIN:
                status = xs_nospace(task);
                break;
        default:
                dprintk("RPC:       sendmsg returned unrecognized error %d\n",
                        -status);
        case -ENETUNREACH:
        case -EPIPE:
        case -ECONNREFUSED:
                /* When the server has died, an ICMP port unreachable message
                 * prompts ECONNREFUSED. */
                clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
        }
out:
        return status;
}

/**
 * xs_tcp_shutdown - gracefully shut down a TCP socket
 * @xprt: transport
 *
 * Initiates a graceful shutdown of the TCP socket by calling the
 * equivalent of shutdown(SHUT_WR);
 */
static void xs_tcp_shutdown(struct rpc_xprt *xprt)
{
        struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
        struct socket *sock = transport->sock;

        if (sock != NULL)
                kernel_sock_shutdown(sock, SHUT_WR);
}

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;

        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) {
                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;
                }

                if (status != 0)
                        continue;
                status = -EAGAIN;
                break;
        }
        if (!transport->sock)
                goto out;

        switch (status) {
        case -ENOTSOCK:
                status = -ENOTCONN;
                /* Should we call xs_close() here? */
                break;
        case -EAGAIN:
                status = xs_nospace(task);
                break;
        default:
                dprintk("RPC:       sendmsg returned unrecognized error %d\n",
                        -status);
        case -ECONNRESET:
        case -EPIPE:
                xs_tcp_shutdown(xprt);
        case -ECONNREFUSED:
        case -ENOTCONN:
                clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
        }
out:
        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);
}

static void xs_save_old_callbacks(struct sock_xprt *transport, struct sock *sk)
{
        transport->old_data_ready = sk->sk_data_ready;
        transport->old_state_change = sk->sk_state_change;
        transport->old_write_space = sk->sk_write_space;
        transport->old_error_report = sk->sk_error_report;
}

static void xs_restore_old_callbacks(struct sock_xprt *transport, struct sock *sk)
{
        sk->sk_data_ready = transport->old_data_ready;
        sk->sk_state_change = transport->old_state_change;
        sk->sk_write_space = transport->old_write_space;
        sk->sk_error_report = transport->old_error_report;
}

static void xs_reset_transport(struct sock_xprt *transport)
{
        struct socket *sock = transport->sock;
        struct sock *sk = transport->inet;

        if (sk == NULL)
                return;

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

        sk->sk_user_data = NULL;

        xs_restore_old_callbacks(transport, sk);
        write_unlock_bh(&sk->sk_callback_lock);

        sk->sk_no_check = 0;

        sock_release(sock);
}

/**
 * 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.
 *
 * The caller _must_ be holding XPRT_LOCKED in order to avoid issues with
 * xs_reset_transport() zeroing the socket from underneath a writer.
 */
static void xs_close(struct rpc_xprt *xprt)
{
        struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);

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

        xs_reset_transport(transport);

        smp_mb__before_clear_bit();
        clear_bit(XPRT_CONNECTION_ABORT, &xprt->state);
        clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
        clear_bit(XPRT_CLOSING, &xprt->state);
        smp_mb__after_clear_bit();
        xprt_disconnect_done(xprt);
}

static void xs_tcp_close(struct rpc_xprt *xprt)
{
        if (test_and_clear_bit(XPRT_CONNECTION_CLOSE, &xprt->state))
                xs_close(xprt);
        else
                xs_tcp_shutdown(xprt);
}

/**
 * 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);

        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)) {
                UDPX_INC_STATS_BH(sk, UDP_MIB_INERRORS);
                goto out_unlock;
        }

        UDPX_INC_STATS_BH(sk, UDP_MIB_INDATAGRAMS);

        /* 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_force_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;
        int read;

        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;
        do {
                rd_desc.count = 65536;
                read = tcp_read_sock(sk, &rd_desc, xs_tcp_data_recv);
        } while (read > 0);
out:
        read_unlock(&sk->sk_callback_lock);
}

/*
 * Do the equivalent of linger/linger2 handling for dealing with
 * broken servers that don't close the socket in a timely
 * fashion
 */
static void xs_tcp_schedule_linger_timeout(struct rpc_xprt *xprt,
                unsigned long timeout)
{
        struct sock_xprt *transport;

        if (xprt_test_and_set_connecting(xprt))
                return;
        set_bit(XPRT_CONNECTION_ABORT, &xprt->state);
        transport = container_of(xprt, struct sock_xprt, xprt);
        queue_delayed_work(rpciod_workqueue, &transport->connect_worker,
                           timeout);
}

static void xs_tcp_cancel_linger_timeout(struct rpc_xprt *xprt)
{
        struct sock_xprt *transport;

        transport = container_of(xprt, struct sock_xprt, xprt);

        if (!test_bit(XPRT_CONNECTION_ABORT, &xprt->state) ||
            !cancel_delayed_work(&transport->connect_worker))
                return;
        clear_bit(XPRT_CONNECTION_ABORT, &xprt->state);
        xprt_clear_connecting(xprt);
}

static void xs_sock_mark_closed(struct rpc_xprt *xprt)
{
        smp_mb__before_clear_bit();
        clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
        clear_bit(XPRT_CLOSING, &xprt->state);
        smp_mb__after_clear_bit();
        /* Mark transport as closed and wake up all pending tasks */
        xprt_disconnect_done(xprt);
}

/**
 * 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_wake_pending_tasks(xprt, -EAGAIN);
                }
                spin_unlock_bh(&xprt->transport_lock);
                break;
        case TCP_FIN_WAIT1:
                /* The client initiated a shutdown of the socket */
                xprt->connect_cookie++;
                xprt->reestablish_timeout = 0;
                set_bit(XPRT_CLOSING, &xprt->state);
                smp_mb__before_clear_bit();
                clear_bit(XPRT_CONNECTED, &xprt->state);
                clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
                smp_mb__after_clear_bit();
                xs_tcp_schedule_linger_timeout(xprt, xs_tcp_fin_timeout);
                break;
        case TCP_CLOSE_WAIT:
                /* The server initiated a shutdown of the socket */
                xprt_force_disconnect(xprt);
        case TCP_SYN_SENT:
                xprt->connect_cookie++;
        case TCP_CLOSING:
                /*
                 * If the server closed down the connection, make sure that
                 * we back off before reconnecting
                 */
                if (xprt->reestablish_timeout < XS_TCP_INIT_REEST_TO)
                        xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
                break;
        case TCP_LAST_ACK:
                set_bit(XPRT_CLOSING, &xprt->state);
                xs_tcp_schedule_linger_timeout(xprt, xs_tcp_fin_timeout);
                smp_mb__before_clear_bit();
                clear_bit(XPRT_CONNECTED, &xprt->state);
                smp_mb__after_clear_bit();
                break;
        case TCP_CLOSE:
                xs_tcp_cancel_linger_timeout(xprt);
                xs_sock_mark_closed(xprt);
        }
 out:
        read_unlock(&sk->sk_callback_lock);
}

/**
 * xs_error_report - callback mainly for catching socket errors
 * @sk: socket
 */
static void xs_error_report(struct sock *sk)
{
        struct rpc_xprt *xprt;

        read_lock(&sk->sk_callback_lock);
        if (!(xprt = xprt_from_sock(sk)))
                goto out;
        dprintk("RPC:       %s client %p...\n"
                        "RPC:       error %d\n",
                        __func__, xprt, sk->sk_err);
        xprt_wake_pending_tasks(xprt, -EAGAIN);
out:
        read_unlock(&sk->sk_callback_lock);
}

static void xs_write_space(struct sock *sk)
{
        struct socket *sock;
        struct rpc_xprt *xprt;

        if (unlikely(!(sock = sk->sk_socket)))
                return;
        clear_bit(SOCK_NOSPACE, &sock->flags);

        if (unlikely(!(xprt = xprt_from_sock(sk))))
                return;
        if (test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags) == 0)
                return;

        xprt_write_space(xprt);
}

/**
 * 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))
                xs_write_space(sk);

        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))
                xs_write_space(sk);

        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 unsigned short xs_get_srcport(struct sock_xprt *transport, struct socket *sock)
{
        unsigned short port = transport->port;

        if (port == 0 && transport->xprt.resvport)
                port = xs_get_random_port();
        return port;
}

static unsigned short xs_next_srcport(struct sock_xprt *transport, struct socket *sock, unsigned short port)
{
        if (transport->port != 0)
                transport->port = 0;
        if (!transport->xprt.resvport)
                return 0;
        if (port <= xprt_min_resvport || port > xprt_max_resvport)
                return xprt_max_resvport;
        return --port;
}

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, nloop = 0;
        unsigned short port = xs_get_srcport(transport, sock);
        unsigned short last;

        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 (port == 0)
                        break;
                if (err == 0) {
                        transport->port = port;
                        break;
                }
                last = port;
                port = xs_next_srcport(transport, sock, port);
                if (port > last)
                        nloop++;
        } while (err == -EADDRINUSE && nloop != 2);
        dprintk("RPC:       %s %pI4:%u: %s (%d)\n",
                        __func__, &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, nloop = 0;
        unsigned short port = xs_get_srcport(transport, sock);
        unsigned short last;

        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 (port == 0)
                        break;
                if (err == 0) {
                        transport->port = port;
                        break;
                }
                last = port;
                port = xs_next_srcport(transport, sock, port);
                if (port > last)
                        nloop++;
        } while (err == -EADDRINUSE && nloop != 2);
        dprintk("RPC:       xs_bind6 %pI6:%u: %s (%d)\n",
                &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);

                xs_save_old_callbacks(transport, sk);

                sk->sk_user_data = xprt;
                sk->sk_data_ready = xs_udp_data_ready;
                sk->sk_write_space = xs_udp_write_space;
                sk->sk_error_report = xs_error_report;
                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)
                goto out;

        /* Start by resetting any existing state */
        xs_reset_transport(transport);

        err = sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock);
        if (err < 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_clear_connecting(xprt);
        xprt_wake_pending_tasks(xprt, status);
}

/**
 * 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)
                goto out;

        /* Start by resetting any existing state */
        xs_reset_transport(transport);

        err = sock_create_kern(PF_INET6, SOCK_DGRAM, IPPROTO_UDP, &sock);
        if (err < 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_clear_connecting(xprt);
        xprt_wake_pending_tasks(xprt, status);
}

/*
 * 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_abort_connection(struct rpc_xprt *xprt, struct sock_xprt *transport)
{
        int result;
        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)
                xs_sock_mark_closed(xprt);
        else
                dprintk("RPC:       AF_UNSPEC connect return code %d\n",
                                result);
}

static void xs_tcp_reuse_connection(struct rpc_xprt *xprt, struct sock_xprt *transport)
{
        unsigned int state = transport->inet->sk_state;

        if (state == TCP_CLOSE && transport->sock->state == SS_UNCONNECTED)
                return;
        if ((1 << state) & (TCPF_ESTABLISHED|TCPF_SYN_SENT))
                return;
        xs_abort_connection(xprt, transport);
}

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);

                xs_save_old_callbacks(transport, sk);

                sk->sk_user_data = xprt;
                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_error_report = xs_error_report;
                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);
        }

        if (!xprt_bound(xprt))
                return -ENOTCONN;

        /* 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_setup_socket - create a TCP socket and connect to a remote endpoint
 * @xprt: RPC transport to connect
 * @transport: socket transport to connect
 * @create_sock: function to create a socket of the correct type
 *
 * Invoked by a work queue tasklet.
 */
static void xs_tcp_setup_socket(struct rpc_xprt *xprt,
                struct sock_xprt *transport,
                struct socket *(*create_sock)(struct rpc_xprt *,
                        struct sock_xprt *))
{
        struct socket *sock = transport->sock;
        int status = -EIO;

        if (xprt->shutdown)
                goto out;

        if (!sock) {
                clear_bit(XPRT_CONNECTION_ABORT, &xprt->state);
                sock = create_sock(xprt, transport);
                if (IS_ERR(sock)) {
                        status = PTR_ERR(sock);
                        goto out;
                }
        } else {
                int abort_and_exit;

                abort_and_exit = test_and_clear_bit(XPRT_CONNECTION_ABORT,
                                &xprt->state);
                /* "close" the socket, preserving the local port */
                xs_tcp_reuse_connection(xprt, transport);

                if (abort_and_exit)
                        goto out_eagain;
        }

        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);
        switch (status) {
        default:
                printk("%s: connect returned unhandled error %d\n",
                        __func__, status);
        case -EADDRNOTAVAIL:
                /* We're probably in TIME_WAIT. Get rid of existing socket,
                 * and retry
                 */
                set_bit(XPRT_CONNECTION_CLOSE, &xprt->state);
                xprt_force_disconnect(xprt);
        case -ECONNREFUSED:
        case -ECONNRESET:
        case -ENETUNREACH:
                /* retry with existing socket, after a delay */
        case 0:
        case -EINPROGRESS:
        case -EALREADY:
                xprt_clear_connecting(xprt);
                return;
        }
out_eagain:
        status = -EAGAIN;
out:
        xprt_clear_connecting(xprt);
        xprt_wake_pending_tasks(xprt, status);
}

static struct socket *xs_create_tcp_sock4(struct rpc_xprt *xprt,
                struct sock_xprt *transport)
{
        struct socket *sock;
        int err;

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

        if (xs_bind4(transport, sock) < 0) {
                sock_release(sock);
                goto out_err;
        }
        return sock;
out_err:
        return ERR_PTR(-EIO);
}

/**
 * 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;

        xs_tcp_setup_socket(xprt, transport, xs_create_tcp_sock4);
}

static struct socket *xs_create_tcp_sock6(struct rpc_xprt *xprt,
                struct sock_xprt *transport)
{
        struct socket *sock;
        int err;

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

        if (xs_bind6(transport, sock) < 0) {
                sock_release(sock);
                goto out_err;
        }
        return sock;
out_err:
        return ERR_PTR(-EIO);
}

/**
 * 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;

        xs_tcp_setup_socket(xprt, transport, xs_create_tcp_sock6);
}

/**
 * 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);
        }
}

static void xs_tcp_connect(struct rpc_task *task)
{
        struct rpc_xprt *xprt = task->tk_xprt;

        /* Exit if we need to wait for socket shutdown to complete */
        if (test_bit(XPRT_CLOSING, &xprt->state))
                return;
        xs_connect(task);
}

/**
 * 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,