[PATCH] RPC: introduce client-side transport switch

 Move the bulk of client-side socket-specific code into a separate source
 file, net/sunrpc/xprtsock.c.

 Test-plan:
 Millions of fsx operations.  Performance characterization such as "sio" or
 "iozone".  Destructive testing (unplugging the network temporarily, server
 reboots).  Connectathon with v2, v3, and v4.

 Version: Thu, 11 Aug 2005 16:03:38 -0400

 Signed-off-by: Chuck Lever <cel@netapp.com>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 1021 insertions, 0 deletions

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
new file mode 100644
index 000000000000..fa1180ac4823
--- /dev/null
+++ b/net/sunrpc/xprtsock.c
@@ -0,0 +1,1021 @@
+/*
+ * 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>
+ */
+
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/capability.h>
+#include <linux/sched.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/file.h>
+
+#include <net/sock.h>
+#include <net/checksum.h>
+#include <net/udp.h>
+#include <net/tcp.h>
+
+#ifdef RPC_DEBUG
+# undef  RPC_DEBUG_DATA
+# define RPCDBG_FACILITY        RPCDBG_XPRT
+#endif
+
+#define XPRT_MAX_RESVPORT       (800)
+
+#ifdef RPC_DEBUG_DATA
+/*
+ * Print the buffer contents (first 128 bytes only--just enough for
+ * diropres return).
+ */
+static void
+xprt_pktdump(char *msg, u32 *packet, unsigned int count)
+{
+        u8      *buf = (u8 *) packet;
+        int     j;
+
+        dprintk("RPC:      %s\n", msg);
+        for (j = 0; j < count && j < 128; j += 4) {
+                if (!(j & 31)) {
+                        if (j)
+                                dprintk("\n");
+                        dprintk("0x%04x ", j);
+                }
+                dprintk("%02x%02x%02x%02x ",
+                        buf[j], buf[j+1], buf[j+2], buf[j+3]);
+        }
+        dprintk("\n");
+}
+#else
+static inline void
+xprt_pktdump(char *msg, u32 *packet, unsigned int count)
+{
+        /* NOP */
+}
+#endif
+
+/*
+ * Look up RPC transport given an INET socket
+ */
+static inline struct rpc_xprt *
+xprt_from_sock(struct sock *sk)
+{
+        return (struct rpc_xprt *) sk->sk_user_data;
+}
+
+static int
+xdr_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen,
+                struct xdr_buf *xdr, unsigned int base, int msgflags)
+{
+        struct page **ppage = xdr->pages;
+        unsigned int len, pglen = xdr->page_len;
+        int err, ret = 0;
+        ssize_t (*sendpage)(struct socket *, struct page *, int, size_t, int);
+
+        len = xdr->head[0].iov_len;
+        if (base < len || (addr != NULL && base == 0)) {
+                struct kvec iov = {
+                        .iov_base = xdr->head[0].iov_base + base,
+                        .iov_len  = len - base,
+                };
+                struct msghdr msg = {
+                        .msg_name    = addr,
+                        .msg_namelen = addrlen,
+                        .msg_flags   = msgflags,
+                };
+                if (xdr->len > len)
+                        msg.msg_flags |= MSG_MORE;
+
+                if (iov.iov_len != 0)
+                        err = kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
+                else
+                        err = kernel_sendmsg(sock, &msg, NULL, 0, 0);
+                if (ret == 0)
+                        ret = err;
+                else if (err > 0)
+                        ret += err;
+                if (err != iov.iov_len)
+                        goto out;
+                base = 0;
+        } else
+                base -= len;
+
+        if (pglen == 0)
+                goto copy_tail;
+        if (base >= pglen) {
+                base -= pglen;
+                goto copy_tail;
+        }
+        if (base || xdr->page_base) {
+                pglen -= base;
+                base  += xdr->page_base;
+                ppage += base >> PAGE_CACHE_SHIFT;
+                base &= ~PAGE_CACHE_MASK;
+        }
+
+        sendpage = sock->ops->sendpage ? : sock_no_sendpage;
+        do {
+                int flags = msgflags;
+
+                len = PAGE_CACHE_SIZE;
+                if (base)
+                        len -= base;
+                if (pglen < len)
+                        len = pglen;
+
+                if (pglen != len || xdr->tail[0].iov_len != 0)
+                        flags |= MSG_MORE;
+
+                /* Hmm... We might be dealing with highmem pages */
+                if (PageHighMem(*ppage))
+                        sendpage = sock_no_sendpage;
+                err = sendpage(sock, *ppage, base, len, flags);
+                if (ret == 0)
+                        ret = err;
+                else if (err > 0)
+                        ret += err;
+                if (err != len)
+                        goto out;
+                base = 0;
+                ppage++;
+        } while ((pglen -= len) != 0);
+copy_tail:
+        len = xdr->tail[0].iov_len;
+        if (base < len) {
+                struct kvec iov = {
+                        .iov_base = xdr->tail[0].iov_base + base,
+                        .iov_len  = len - base,
+                };
+                struct msghdr msg = {
+                        .msg_flags   = msgflags,
+                };
+                err = kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
+                if (ret == 0)
+                        ret = err;
+                else if (err > 0)
+                        ret += err;
+        }
+out:
+        return ret;
+}
+
+/*
+ * Write data to socket.
+ */
+static inline int
+xprt_sendmsg(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+        struct socket   *sock = xprt->sock;
+        struct xdr_buf  *xdr = &req->rq_snd_buf;
+        struct sockaddr *addr = NULL;
+        int addrlen = 0;
+        unsigned int    skip;
+        int             result;
+
+        if (!sock)
+                return -ENOTCONN;
+
+        xprt_pktdump("packet data:",
+                                req->rq_svec->iov_base,
+                                req->rq_svec->iov_len);
+
+        /* For UDP, we need to provide an address */
+        if (!xprt->stream) {
+                addr = (struct sockaddr *) &xprt->addr;
+                addrlen = sizeof(xprt->addr);
+        }
+        /* Dont repeat bytes */
+        skip = req->rq_bytes_sent;
+
+        clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
+        result = xdr_sendpages(sock, addr, addrlen, xdr, skip, MSG_DONTWAIT);
+
+        dprintk("RPC:      xprt_sendmsg(%d) = %d\n", xdr->len - skip, result);
+
+        if (result >= 0)
+                return result;
+
+        switch (result) {
+        case -ECONNREFUSED:
+                /* When the server has died, an ICMP port unreachable message
+                 * prompts ECONNREFUSED.
+                 */
+        case -EAGAIN:
+                break;
+        case -ECONNRESET:
+        case -ENOTCONN:
+        case -EPIPE:
+                /* connection broken */
+                if (xprt->stream)
+                        result = -ENOTCONN;
+                break;
+        default:
+                printk(KERN_NOTICE "RPC: sendmsg returned error %d\n", -result);
+        }
+        return result;
+}
+
+static int
+xprt_send_request(struct rpc_task *task)
+{
+        struct rpc_rqst *req = task->tk_rqstp;
+        struct rpc_xprt *xprt = req->rq_xprt;
+        int status, retry = 0;
+
+        /* set up everything as needed. */
+        /* Write the record marker */
+        if (xprt->stream) {
+                u32     *marker = req->rq_svec[0].iov_base;
+
+                *marker = htonl(0x80000000|(req->rq_slen-sizeof(*marker)));
+        }
+
+        /* Continue transmitting the packet/record. We must be careful
+         * to cope with writespace callbacks arriving _after_ we have
+         * called xprt_sendmsg().
+         */
+        while (1) {
+                req->rq_xtime = jiffies;
+                status = xprt_sendmsg(xprt, req);
+
+                if (status < 0)
+                        break;
+
+                if (xprt->stream) {
+                        req->rq_bytes_sent += status;
+
+                        /* If we've sent the entire packet, immediately
+                         * reset the count of bytes sent. */
+                        if (req->rq_bytes_sent >= req->rq_slen) {
+                                req->rq_bytes_sent = 0;
+                                return 0;
+                        }
+                } else {
+                        if (status >= req->rq_slen)
+                                return 0;
+                        status = -EAGAIN;
+                        break;
+                }
+
+                dprintk("RPC: %4d xmit incomplete (%d left of %d)\n",
+                                task->tk_pid, req->rq_slen - req->rq_bytes_sent,
+                                req->rq_slen);
+
+                status = -EAGAIN;
+                if (retry++ > 50)
+                        break;
+        }
+
+        if (status == -EAGAIN) {
+                if (test_bit(SOCK_ASYNC_NOSPACE, &xprt->sock->flags)) {
+                        /* Protect against races with xprt_write_space */
+                        spin_lock_bh(&xprt->sock_lock);
+                        /* Don't race with disconnect */
+                        if (!xprt_connected(xprt))
+                                task->tk_status = -ENOTCONN;
+                        else if (test_bit(SOCK_NOSPACE, &xprt->sock->flags)) {
+                                task->tk_timeout = req->rq_timeout;
+                                rpc_sleep_on(&xprt->pending, task, NULL, NULL);
+                        }
+                        spin_unlock_bh(&xprt->sock_lock);
+                        return status;
+                }
+                /* Keep holding the socket if it is blocked */
+                rpc_delay(task, HZ>>4);
+        }
+        return status;
+}
+
+/*
+ * Close down a transport socket
+ */
+static void
+xprt_close(struct rpc_xprt *xprt)
+{
+        struct socket   *sock = xprt->sock;
+        struct sock     *sk = xprt->inet;
+
+        if (!sk)
+                return;
+
+        write_lock_bh(&sk->sk_callback_lock);
+        xprt->inet = NULL;
+        xprt->sock = NULL;
+
+        sk->sk_user_data    = NULL;
+        sk->sk_data_ready   = xprt->old_data_ready;
+        sk->sk_state_change = xprt->old_state_change;
+        sk->sk_write_space  = xprt->old_write_space;
+        write_unlock_bh(&sk->sk_callback_lock);
+
+        sk->sk_no_check  = 0;
+
+        sock_release(sock);
+}
+
+static void xprt_socket_destroy(struct rpc_xprt *xprt)
+{
+        cancel_delayed_work(&xprt->sock_connect);
+        flush_scheduled_work();
+
+        xprt_disconnect(xprt);
+        xprt_close(xprt);
+        kfree(xprt->slot);
+}
+
+/*
+ * Input handler for RPC replies. Called from a bottom half and hence
+ * atomic.
+ */
+static void
+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, *xp;
+
+        read_lock(&sk->sk_callback_lock);
+        dprintk("RPC:      udp_data_ready...\n");
+        if (!(xprt = xprt_from_sock(sk))) {
+                printk("RPC:      udp_data_ready request not found!\n");
+                goto out;
+        }
+
+        dprintk("RPC:      udp_data_ready client %p\n", xprt);
+
+        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) {
+                printk("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->sock_lock);
+        rovr = xprt_lookup_rqst(xprt, *xp);
+        if (!rovr)
+                goto out_unlock;
+        task = rovr->rq_task;
+
+        dprintk("RPC: %4d received reply\n", task->tk_pid);
+
+        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_complete_rqst(xprt, rovr, copied);
+
+ out_unlock:
+        spin_unlock(&xprt->sock_lock);
+ dropit:
+        skb_free_datagram(sk, skb);
+ out:
+        read_unlock(&sk->sk_callback_lock);
+}
+
+/*
+ * Copy from an skb into memory and shrink the skb.
+ */
+static inline size_t
+tcp_copy_data(skb_reader_t *desc, void *p, size_t len)
+{
+        if (len > desc->count)
+                len = desc->count;
+        if (skb_copy_bits(desc->skb, desc->offset, p, len)) {
+                dprintk("RPC:      failed to copy %zu bytes from skb. %zu bytes remain\n",
+                                len, desc->count);
+                return 0;
+        }
+        desc->offset += len;
+        desc->count -= len;
+        dprintk("RPC:      copied %zu bytes from skb. %zu bytes remain\n",
+                        len, desc->count);
+        return len;
+}
+
+/*
+ * TCP read fragment marker
+ */
+static inline void
+tcp_read_fraghdr(struct rpc_xprt *xprt, skb_reader_t *desc)
+{
+        size_t len, used;
+        char *p;
+
+        p = ((char *) &xprt->tcp_recm) + xprt->tcp_offset;
+        len = sizeof(xprt->tcp_recm) - xprt->tcp_offset;
+        used = tcp_copy_data(desc, p, len);
+        xprt->tcp_offset += used;
+        if (used != len)
+                return;
+        xprt->tcp_reclen = ntohl(xprt->tcp_recm);
+        if (xprt->tcp_reclen & 0x80000000)
+                xprt->tcp_flags |= XPRT_LAST_FRAG;
+        else
+                xprt->tcp_flags &= ~XPRT_LAST_FRAG;
+        xprt->tcp_reclen &= 0x7fffffff;
+        xprt->tcp_flags &= ~XPRT_COPY_RECM;
+        xprt->tcp_offset = 0;
+        /* Sanity check of the record length */
+        if (xprt->tcp_reclen < 4) {
+                printk(KERN_ERR "RPC: Invalid TCP record fragment length\n");
+                xprt_disconnect(xprt);
+        }
+        dprintk("RPC:      reading TCP record fragment of length %d\n",
+                        xprt->tcp_reclen);
+}
+
+static void
+tcp_check_recm(struct rpc_xprt *xprt)
+{
+        dprintk("RPC:      xprt = %p, tcp_copied = %lu, tcp_offset = %u, tcp_reclen = %u, tcp_flags = %lx\n",
+                        xprt, xprt->tcp_copied, xprt->tcp_offset, xprt->tcp_reclen, xprt->tcp_flags);
+        if (xprt->tcp_offset == xprt->tcp_reclen) {
+                xprt->tcp_flags |= XPRT_COPY_RECM;
+                xprt->tcp_offset = 0;
+                if (xprt->tcp_flags & XPRT_LAST_FRAG) {
+                        xprt->tcp_flags &= ~XPRT_COPY_DATA;
+                        xprt->tcp_flags |= XPRT_COPY_XID;
+                        xprt->tcp_copied = 0;
+                }
+        }
+}
+
+/*
+ * TCP read xid
+ */
+static inline void
+tcp_read_xid(struct rpc_xprt *xprt, skb_reader_t *desc)
+{
+        size_t len, used;
+        char *p;
+
+        len = sizeof(xprt->tcp_xid) - xprt->tcp_offset;
+        dprintk("RPC:      reading XID (%Zu bytes)\n", len);
+        p = ((char *) &xprt->tcp_xid) + xprt->tcp_offset;
+        used = tcp_copy_data(desc, p, len);
+        xprt->tcp_offset += used;
+        if (used != len)
+                return;
+        xprt->tcp_flags &= ~XPRT_COPY_XID;
+        xprt->tcp_flags |= XPRT_COPY_DATA;
+        xprt->tcp_copied = 4;
+        dprintk("RPC:      reading reply for XID %08x\n",
+                                                ntohl(xprt->tcp_xid));
+        tcp_check_recm(xprt);
+}
+
+/*
+ * TCP read and complete request
+ */
+static inline void
+tcp_read_request(struct rpc_xprt *xprt, skb_reader_t *desc)
+{
+        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->sock_lock);
+        req = xprt_lookup_rqst(xprt, xprt->tcp_xid);
+        if (!req) {
+                xprt->tcp_flags &= ~XPRT_COPY_DATA;
+                dprintk("RPC:      XID %08x request not found!\n",
+                                ntohl(xprt->tcp_xid));
+                spin_unlock(&xprt->sock_lock);
+                return;
+        }
+
+        rcvbuf = &req->rq_private_buf;
+        len = desc->count;
+        if (len > xprt->tcp_reclen - xprt->tcp_offset) {
+                skb_reader_t my_desc;
+
+                len = xprt->tcp_reclen - xprt->tcp_offset;
+                memcpy(&my_desc, desc, sizeof(my_desc));
+                my_desc.count = len;
+                r = xdr_partial_copy_from_skb(rcvbuf, xprt->tcp_copied,
+                                          &my_desc, tcp_copy_data);
+                desc->count -= r;
+                desc->offset += r;
+        } else
+                r = xdr_partial_copy_from_skb(rcvbuf, xprt->tcp_copied,
+                                          desc, tcp_copy_data);
+
+        if (r > 0) {
+                xprt->tcp_copied += r;
+                xprt->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 XPRT_COPY_DATA, so the request
+                 * will not receive any additional updates,
+                 * and time out.
+                 * Any remaining data from this record will
+                 * be discarded.
+                 */
+                xprt->tcp_flags &= ~XPRT_COPY_DATA;
+                dprintk("RPC:      XID %08x truncated request\n",
+                                ntohl(xprt->tcp_xid));
+                dprintk("RPC:      xprt = %p, tcp_copied = %lu, tcp_offset = %u, tcp_reclen = %u\n",
+                                xprt, xprt->tcp_copied, xprt->tcp_offset, xprt->tcp_reclen);
+                goto out;
+        }
+
+        dprintk("RPC:      XID %08x read %Zd bytes\n",
+                        ntohl(xprt->tcp_xid), r);
+        dprintk("RPC:      xprt = %p, tcp_copied = %lu, tcp_offset = %u, tcp_reclen = %u\n",
+                        xprt, xprt->tcp_copied, xprt->tcp_offset, xprt->tcp_reclen);
+
+        if (xprt->tcp_copied == req->rq_private_buf.buflen)
+                xprt->tcp_flags &= ~XPRT_COPY_DATA;
+        else if (xprt->tcp_offset == xprt->tcp_reclen) {
+                if (xprt->tcp_flags & XPRT_LAST_FRAG)
+                        xprt->tcp_flags &= ~XPRT_COPY_DATA;
+        }
+
+out:
+        if (!(xprt->tcp_flags & XPRT_COPY_DATA)) {
+                dprintk("RPC: %4d received reply complete\n",
+                                req->rq_task->tk_pid);
+                xprt_complete_rqst(xprt, req, xprt->tcp_copied);
+        }
+        spin_unlock(&xprt->sock_lock);
+        tcp_check_recm(xprt);
+}
+
+/*
+ * TCP discard extra bytes from a short read
+ */
+static inline void
+tcp_read_discard(struct rpc_xprt *xprt, skb_reader_t *desc)
+{
+        size_t len;
+
+        len = xprt->tcp_reclen - xprt->tcp_offset;
+        if (len > desc->count)
+                len = desc->count;
+        desc->count -= len;
+        desc->offset += len;
+        xprt->tcp_offset += len;
+        dprintk("RPC:      discarded %Zu bytes\n", len);
+        tcp_check_recm(xprt);
+}
+
+/*
+ * TCP record receive routine
+ * We first have to grab the record marker, then the XID, then the data.
+ */
+static int
+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;
+        skb_reader_t desc = {
+                .skb    = skb,
+                .offset = offset,
+                .count  = len,
+                .csum   = 0
+        };
+
+        dprintk("RPC:      tcp_data_recv\n");
+        do {
+                /* Read in a new fragment marker if necessary */
+                /* Can we ever really expect to get completely empty fragments? */
+                if (xprt->tcp_flags & XPRT_COPY_RECM) {
+                        tcp_read_fraghdr(xprt, &desc);
+                        continue;
+                }
+                /* Read in the xid if necessary */
+                if (xprt->tcp_flags & XPRT_COPY_XID) {
+                        tcp_read_xid(xprt, &desc);
+                        continue;
+                }
+                /* Read in the request data */
+                if (xprt->tcp_flags & XPRT_COPY_DATA) {
+                        tcp_read_request(xprt, &desc);
+                        continue;
+                }
+                /* Skip over any trailing bytes on short reads */
+                tcp_read_discard(xprt, &desc);
+        } while (desc.count);
+        dprintk("RPC:      tcp_data_recv done\n");
+        return len - desc.count;
+}
+
+static void tcp_data_ready(struct sock *sk, int bytes)
+{
+        struct rpc_xprt *xprt;
+        read_descriptor_t rd_desc;
+
+        read_lock(&sk->sk_callback_lock);
+        dprintk("RPC:      tcp_data_ready...\n");
+        if (!(xprt = xprt_from_sock(sk))) {
+                printk("RPC:      tcp_data_ready socket info not found!\n");
+                goto out;
+        }
+        if (xprt->shutdown)
+                goto out;
+
+        /* We use rd_desc to pass struct xprt to tcp_data_recv */
+        rd_desc.arg.data = xprt;
+        rd_desc.count = 65536;
+        tcp_read_sock(sk, &rd_desc, tcp_data_recv);
+out:
+        read_unlock(&sk->sk_callback_lock);
+}
+
+static void
+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:      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->sock_lock);
+                if (!xprt_test_and_set_connected(xprt)) {
+                        /* Reset TCP record info */
+                        xprt->tcp_offset = 0;
+                        xprt->tcp_reclen = 0;
+                        xprt->tcp_copied = 0;
+                        xprt->tcp_flags = XPRT_COPY_RECM | XPRT_COPY_XID;
+                        rpc_wake_up(&xprt->pending);
+                }
+                spin_unlock_bh(&xprt->sock_lock);
+                break;
+        case TCP_SYN_SENT:
+        case TCP_SYN_RECV:
+                break;
+        default:
+                xprt_disconnect(xprt);
+                break;
+        }
+ out:
+        read_unlock(&sk->sk_callback_lock);
+}
+
+/*
+ * 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 sock_sendmsg
+ * with a bunch of small requests.
+ */
+static void
+xprt_write_space(struct sock *sk)
+{
+        struct rpc_xprt *xprt;
+        struct socket   *sock;
+
+        read_lock(&sk->sk_callback_lock);
+        if (!(xprt = xprt_from_sock(sk)) || !(sock = sk->sk_socket))
+                goto out;
+        if (xprt->shutdown)
+                goto out;
+
+        /* Wait until we have enough socket memory */
+        if (xprt->stream) {
+                /* from net/core/stream.c:sk_stream_write_space */
+                if (sk_stream_wspace(sk) < sk_stream_min_wspace(sk))
+                        goto out;
+        } else {
+                /* from net/core/sock.c:sock_def_write_space */
+                if (!sock_writeable(sk))
+                        goto out;
+        }
+
+        if (!test_and_clear_bit(SOCK_NOSPACE, &sock->flags))
+                goto out;
+
+        spin_lock_bh(&xprt->sock_lock);
+        if (xprt->snd_task)
+                rpc_wake_up_task(xprt->snd_task);
+        spin_unlock_bh(&xprt->sock_lock);
+out:
+        read_unlock(&sk->sk_callback_lock);
+}
+
+/*
+ * Set socket buffer length
+ */
+static void
+xprt_sock_setbufsize(struct rpc_xprt *xprt)
+{
+        struct sock *sk = xprt->inet;
+
+        if (xprt->stream)
+                return;
+        if (xprt->rcvsize) {
+                sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
+                sk->sk_rcvbuf = xprt->rcvsize * xprt->max_reqs *  2;
+        }
+        if (xprt->sndsize) {
+                sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
+                sk->sk_sndbuf = xprt->sndsize * xprt->max_reqs * 2;
+                sk->sk_write_space(sk);
+        }
+}
+
+/*
+ * Bind to a reserved port
+ */
+static inline int xprt_bindresvport(struct rpc_xprt *xprt, struct socket *sock)
+{
+        struct sockaddr_in myaddr = {
+                .sin_family = AF_INET,
+        };
+        int             err, port;
+
+        /* Were we already bound to a given port? Try to reuse it */
+        port = xprt->port;
+        do {
+                myaddr.sin_port = htons(port);
+                err = sock->ops->bind(sock, (struct sockaddr *) &myaddr,
+                                                sizeof(myaddr));
+                if (err == 0) {
+                        xprt->port = port;
+                        return 0;
+                }
+                if (--port == 0)
+                        port = XPRT_MAX_RESVPORT;
+        } while (err == -EADDRINUSE && port != xprt->port);
+
+        printk("RPC: Can't bind to reserved port (%d).\n", -err);
+        return err;
+}
+
+static void
+xprt_bind_socket(struct rpc_xprt *xprt, struct socket *sock)
+{
+        struct sock     *sk = sock->sk;
+
+        if (xprt->inet)
+                return;
+
+        write_lock_bh(&sk->sk_callback_lock);
+        sk->sk_user_data = xprt;
+        xprt->old_data_ready = sk->sk_data_ready;
+        xprt->old_state_change = sk->sk_state_change;
+        xprt->old_write_space = sk->sk_write_space;
+        if (xprt->prot == IPPROTO_UDP) {
+                sk->sk_data_ready = udp_data_ready;
+                sk->sk_no_check = UDP_CSUM_NORCV;
+                xprt_set_connected(xprt);
+        } else {
+                tcp_sk(sk)->nonagle = 1;        /* disable Nagle's algorithm */
+                sk->sk_data_ready = tcp_data_ready;
+                sk->sk_state_change = tcp_state_change;
+                xprt_clear_connected(xprt);
+        }
+        sk->sk_write_space = xprt_write_space;
+
+        /* Reset to new socket */
+        xprt->sock = sock;
+        xprt->inet = sk;
+        write_unlock_bh(&sk->sk_callback_lock);
+
+        return;
+}
+
+/*
+ * Datastream sockets are created here, but xprt_connect will create
+ * and connect stream sockets.
+ */
+static struct socket * xprt_create_socket(struct rpc_xprt *xprt, int proto, int resvport)
+{
+        struct socket   *sock;
+        int             type, err;
+
+        dprintk("RPC:      xprt_create_socket(%s %d)\n",
+                           (proto == IPPROTO_UDP)? "udp" : "tcp", proto);
+
+        type = (proto == IPPROTO_UDP)? SOCK_DGRAM : SOCK_STREAM;
+
+        if ((err = sock_create_kern(PF_INET, type, proto, &sock)) < 0) {
+                printk("RPC: can't create socket (%d).\n", -err);
+                return NULL;
+        }
+
+        /* If the caller has the capability, bind to a reserved port */
+        if (resvport && xprt_bindresvport(xprt, sock) < 0) {
+                printk("RPC: can't bind to reserved port.\n");
+                goto failed;
+        }
+
+        return sock;
+
+failed:
+        sock_release(sock);
+        return NULL;
+}
+
+static void xprt_socket_connect(void *args)
+{
+        struct rpc_xprt *xprt = (struct rpc_xprt *)args;
+        struct socket *sock = xprt->sock;
+        int status = -EIO;
+
+        if (xprt->shutdown || xprt->addr.sin_port == 0)
+                goto out;
+
+        /*
+         * Start by resetting any existing state
+         */
+        xprt_close(xprt);
+        sock = xprt_create_socket(xprt, xprt->prot, xprt->resvport);
+        if (sock == NULL) {
+                /* couldn't create socket or bind to reserved port;
+                 * this is likely a permanent error, so cause an abort */
+                goto out;
+        }
+        xprt_bind_socket(xprt, sock);
+        xprt_sock_setbufsize(xprt);
+
+        status = 0;
+        if (!xprt->stream)
+                goto out;
+
+        /*
+         * Tell the socket layer to start connecting...
+         */
+        status = sock->ops->connect(sock, (struct sockaddr *) &xprt->addr,
+                        sizeof(xprt->addr), O_NONBLOCK);
+        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;
+                }
+        }
+out:
+        if (status < 0)
+                rpc_wake_up_status(&xprt->pending, status);
+        else
+                rpc_wake_up(&xprt->pending);
+out_clear:
+        smp_mb__before_clear_bit();
+        clear_bit(XPRT_CONNECTING, &xprt->sockstate);
+        smp_mb__after_clear_bit();
+}
+
+static void
+xprt_connect_sock(struct rpc_task *task)
+{
+        struct rpc_xprt *xprt = task->tk_xprt;
+
+        if (!test_and_set_bit(XPRT_CONNECTING, &xprt->sockstate)) {
+                /* Note: if we are here due to a dropped connection
+                 *       we delay reconnecting by RPC_REESTABLISH_TIMEOUT/HZ
+                 *       seconds
+                 */
+                if (xprt->sock != NULL)
+                        schedule_delayed_work(&xprt->sock_connect,
+                                        RPC_REESTABLISH_TIMEOUT);
+                else {
+                        schedule_work(&xprt->sock_connect);
+                        /* flush_scheduled_work can sleep... */
+                        if (!RPC_IS_ASYNC(task))
+                                flush_scheduled_work();
+                }
+        }
+}
+
+/*
+ * Set default timeout parameters
+ */
+static void
+xprt_default_timeout(struct rpc_timeout *to, int proto)
+{
+        if (proto == IPPROTO_UDP)
+                xprt_set_timeout(to, 5,  5 * HZ);
+        else
+                xprt_set_timeout(to, 2, 60 * HZ);
+}
+
+static struct rpc_xprt_ops xprt_socket_ops = {
+        .set_buffer_size        = xprt_sock_setbufsize,
+        .connect                = xprt_connect_sock,
+        .send_request           = xprt_send_request,
+        .close                  = xprt_close,
+        .destroy                = xprt_socket_destroy,
+};
+
+extern unsigned int xprt_udp_slot_table_entries;
+extern unsigned int xprt_tcp_slot_table_entries;
+
+int xs_setup_udp(struct rpc_xprt *xprt, struct rpc_timeout *to)
+{
+        size_t slot_table_size;
+
+        dprintk("RPC:      setting up udp-ipv4 transport...\n");
+
+        xprt->max_reqs = xprt_udp_slot_table_entries;
+        slot_table_size = xprt->max_reqs * sizeof(xprt->slot[0]);
+        xprt->slot = kmalloc(slot_table_size, GFP_KERNEL);
+        if (xprt->slot == NULL)
+                return -ENOMEM;
+        memset(xprt->slot, 0, slot_table_size);
+
+        xprt->prot = IPPROTO_UDP;
+        xprt->port = XPRT_MAX_RESVPORT;
+        xprt->stream = 0;
+        xprt->nocong = 0;
+        xprt->cwnd = RPC_INITCWND;
+        xprt->resvport = capable(CAP_NET_BIND_SERVICE) ? 1 : 0;
+        /* XXX: header size can vary due to auth type, IPv6, etc. */
+        xprt->max_payload = (1U << 16) - (MAX_HEADER << 3);
+
+        INIT_WORK(&xprt->sock_connect, xprt_socket_connect, xprt);
+
+        xprt->ops = &xprt_socket_ops;
+
+        if (to)
+                xprt->timeout = *to;
+        else
+                xprt_default_timeout(to, xprt->prot);
+
+        return 0;
+}
+
+int xs_setup_tcp(struct rpc_xprt *xprt, struct rpc_timeout *to)
+{
+        size_t slot_table_size;
+
+        dprintk("RPC:      setting up tcp-ipv4 transport...\n");
+
+        xprt->max_reqs = xprt_tcp_slot_table_entries;
+        slot_table_size = xprt->max_reqs * sizeof(xprt->slot[0]);
+        xprt->slot = kmalloc(slot_table_size, GFP_KERNEL);
+        if (xprt->slot == NULL)
+                return -ENOMEM;
+        memset(xprt->slot, 0, slot_table_size);
+
+        xprt->prot = IPPROTO_TCP;
+        xprt->port = XPRT_MAX_RESVPORT;
+        xprt->stream = 1;
+        xprt->nocong = 1;
+        xprt->cwnd = RPC_MAXCWND(xprt);
+        xprt->resvport = capable(CAP_NET_BIND_SERVICE) ? 1 : 0;
+        xprt->max_payload = (1U << 31) - 1;
+
+        INIT_WORK(&xprt->sock_connect, xprt_socket_connect, xprt);
+
+        xprt->ops = &xprt_socket_ops;
+
+        if (to)
+                xprt->timeout = *to;
+        else
+                xprt_default_timeout(to, xprt->prot);
+
+        return 0;
+}