Merge ../bleed-2.6

1 files changed, 1252 insertions, 0 deletions

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
new file mode 100644
index 00000000000..2e1529217e6
--- /dev/null
+++ b/net/sunrpc/xprtsock.c
@@ -0,0 +1,1252 @@
+/*
+ * linux/net/sunrpc/xprtsock.c
+ *
+ * Client-side transport implementation for sockets.
+ *
+ * TCP callback races fixes (C) 1998 Red Hat Software <alan@redhat.com>
+ * TCP send fixes (C) 1998 Red Hat Software <alan@redhat.com>
+ * TCP NFS related read + write fixes
+ *  (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
+ *
+ * Rewrite of larges part of the code in order to stabilize TCP stuff.
+ * Fix behaviour when socket buffer is full.
+ *  (C) 1999 Trond Myklebust <trond.myklebust@fys.uio.no>
+ *
+ * IP socket transport implementation, (C) 2005 Chuck Lever <cel@netapp.com>
+ */
+
+#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>
+
+/*
+ * How many times to try sending a request on a socket before waiting
+ * for the socket buffer to clear.
+ */
+#define XS_SENDMSG_RETRY	(10U)
+
+/*
+ * Time out for an RPC UDP socket connect.  UDP socket connects are
+ * synchronous, but we set a timeout anyway in case of resource
+ * exhaustion on the local host.
+ */
+#define XS_UDP_CONN_TO		(5U * HZ)
+
+/*
+ * Wait duration for an RPC TCP connection to be established.  Solaris
+ * NFS over TCP uses 60 seconds, for example, which is in line with how
+ * long a server takes to reboot.
+ */
+#define XS_TCP_CONN_TO		(60U * HZ)
+
+/*
+ * Wait duration for a reply from the RPC portmapper.
+ */
+#define XS_BIND_TO		(60U * HZ)
+
+/*
+ * Delay if a UDP socket connect error occurs.  This is most likely some
+ * kind of resource problem on the local host.
+ */
+#define XS_UDP_REEST_TO		(2U * HZ)
+
+/*
+ * The reestablish timeout allows clients to delay for a bit before attempting
+ * to reconnect to a server that just dropped our connection.
+ *
+ * We implement an exponential backoff when trying to reestablish a TCP
+ * transport connection with the server.  Some servers like to drop a TCP
+ * connection when they are overworked, so we start with a short timeout and
+ * increase over time if the server is down or not responding.
+ */
+#define XS_TCP_INIT_REEST_TO	(3U * HZ)
+#define XS_TCP_MAX_REEST_TO	(5U * 60 * HZ)
+
+/*
+ * TCP idle timeout; client drops the transport socket if it is idle
+ * for this long.  Note that we also timeout UDP sockets to prevent
+ * holding port numbers when there is no RPC traffic.
+ */
+#define XS_IDLE_DISC_TO		(5U * 60 * HZ)
+
+#ifdef RPC_DEBUG
+# undef  RPC_DEBUG_DATA
+# define RPCDBG_FACILITY	RPCDBG_TRANS
+#endif
+
+#ifdef RPC_DEBUG_DATA
+static void xs_pktdump(char *msg, u32 *packet, unsigned int count)
+{
+	u8 *buf = (u8 *) packet;
+	int j;
+
+	dprintk("RPC:      %s\n", msg);
+	for (j = 0; j < count && j < 128; j += 4) {
+		if (!(j & 31)) {
+			if (j)
+				dprintk("\n");
+			dprintk("0x%04x ", j);
+		}
+		dprintk("%02x%02x%02x%02x ",
+			buf[j], buf[j+1], buf[j+2], buf[j+3]);
+	}
+	dprintk("\n");
+}
+#else
+static inline void xs_pktdump(char *msg, u32 *packet, unsigned int count)
+{
+	/* NOP */
+}
+#endif
+
+#define XS_SENDMSG_FLAGS	(MSG_DONTWAIT | MSG_NOSIGNAL)
+
+static inline int xs_send_head(struct socket *sock, struct sockaddr *addr, int addrlen, struct xdr_buf *xdr, unsigned int base, unsigned int len)
+{
+	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	= XS_SENDMSG_FLAGS,
+	};
+
+	if (xdr->len > len)
+		msg.msg_flags |= MSG_MORE;
+
+	if (likely(iov.iov_len))
+		return kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
+	return kernel_sendmsg(sock, &msg, NULL, 0, 0);
+}
+
+static int xs_send_tail(struct socket *sock, struct xdr_buf *xdr, unsigned int base, unsigned int len)
+{
+	struct kvec iov = {
+		.iov_base	= xdr->tail[0].iov_base + base,
+		.iov_len	= len - base,
+	};
+	struct msghdr msg = {
+		.msg_flags	= XS_SENDMSG_FLAGS,
+	};
+
+	return kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
+}
+
+/**
+ * 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 inline int xs_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen, struct xdr_buf *xdr, unsigned int base)
+{
+	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);
+
+	if (unlikely(!sock))
+		return -ENOTCONN;
+
+	clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
+
+	len = xdr->head[0].iov_len;
+	if (base < len || (addr != NULL && base == 0)) {
+		err = xs_send_head(sock, addr, addrlen, xdr, base, len);
+		if (ret == 0)
+			ret = err;
+		else if (err > 0)
+			ret += err;
+		if (err != (len - base))
+			goto out;
+		base = 0;
+	} else
+		base -= len;
+
+	if (unlikely(pglen == 0))
+		goto copy_tail;
+	if (unlikely(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 = XS_SENDMSG_FLAGS;
+
+		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) {
+		err = xs_send_tail(sock, xdr, base, len);
+		if (ret == 0)
+			ret = err;
+		else if (err > 0)
+			ret += err;
+	}
+out:
+	return ret;
+}
+
+/**
+ * xs_nospace - place task on wait queue if transmit was incomplete
+ * @task: task to put to sleep
+ *
+ */
+static void xs_nospace(struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+	struct rpc_xprt *xprt = req->rq_xprt;
+
+	dprintk("RPC: %4d xmit incomplete (%u left of %u)\n",
+			task->tk_pid, req->rq_slen - req->rq_bytes_sent,
+			req->rq_slen);
+
+	if (test_bit(SOCK_ASYNC_NOSPACE, &xprt->sock->flags)) {
+		/* Protect against races with write_space */
+		spin_lock_bh(&xprt->transport_lock);
+
+		/* Don't race with disconnect */
+		if (!xprt_connected(xprt))
+			task->tk_status = -ENOTCONN;
+		else if (test_bit(SOCK_NOSPACE, &xprt->sock->flags))
+			xprt_wait_for_buffer_space(task);
+
+		spin_unlock_bh(&xprt->transport_lock);
+	} else
+		/* Keep holding the socket if it is blocked */
+		rpc_delay(task, HZ>>4);
+}
+
+/**
+ * xs_udp_send_request - write an RPC request to a UDP socket
+ * @task: address of RPC task that manages the state of an RPC request
+ *
+ * Return values:
+ *        0:	The request has been sent
+ *   EAGAIN:	The socket was blocked, please call again later to
+ *		complete the request
+ * ENOTCONN:	Caller needs to invoke connect logic then call again
+ *    other:	Some other error occured, the request was not sent
+ */
+static int xs_udp_send_request(struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+	struct rpc_xprt *xprt = req->rq_xprt;
+	struct xdr_buf *xdr = &req->rq_snd_buf;
+	int status;
+
+	xs_pktdump("packet data:",
+				req->rq_svec->iov_base,
+				req->rq_svec->iov_len);
+
+	req->rq_xtime = jiffies;
+	status = xs_sendpages(xprt->sock, (struct sockaddr *) &xprt->addr,
+				sizeof(xprt->addr), xdr, req->rq_bytes_sent);
+
+	dprintk("RPC:      xs_udp_send_request(%u) = %d\n",
+			xdr->len - req->rq_bytes_sent, status);
+
+	if (likely(status >= (int) req->rq_slen))
+		return 0;
+
+	/* Still some bytes left; set up for a retry later. */
+	if (status > 0)
+		status = -EAGAIN;
+
+	switch (status) {
+	case -ENETUNREACH:
+	case -EPIPE:
+	case -ECONNREFUSED:
+		/* When the server has died, an ICMP port unreachable message
+		 * prompts ECONNREFUSED. */
+		break;
+	case -EAGAIN:
+		xs_nospace(task);
+		break;
+	default:
+		dprintk("RPC:      sendmsg returned unrecognized error %d\n",
+			-status);
+		break;
+	}
+
+	return status;
+}
+
+static inline void xs_encode_tcp_record_marker(struct xdr_buf *buf)
+{
+	u32 reclen = buf->len - sizeof(rpc_fraghdr);
+	rpc_fraghdr *base = buf->head[0].iov_base;
+	*base = htonl(RPC_LAST_STREAM_FRAGMENT | reclen);
+}
+
+/**
+ * xs_tcp_send_request - write an RPC request to a TCP socket
+ * @task: address of RPC task that manages the state of an RPC request
+ *
+ * Return values:
+ *        0:	The request has been sent
+ *   EAGAIN:	The socket was blocked, please call again later to
+ *		complete the request
+ * ENOTCONN:	Caller needs to invoke connect logic then call again
+ *    other:	Some other error occured, the request was not sent
+ *
+ * XXX: In the case of soft timeouts, should we eventually give up
+ *	if sendmsg is not able to make progress?
+ */
+static int xs_tcp_send_request(struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+	struct rpc_xprt *xprt = req->rq_xprt;
+	struct xdr_buf *xdr = &req->rq_snd_buf;
+	int status, retry = 0;
+
+	xs_encode_tcp_record_marker(&req->rq_snd_buf);
+
+	xs_pktdump("packet data:",
+				req->rq_svec->iov_base,
+				req->rq_svec->iov_len);
+
+	/* Continue transmitting the packet/record. We must be careful
+	 * to cope with writespace callbacks arriving _after_ we have
+	 * called sendmsg(). */
+	while (1) {
+		req->rq_xtime = jiffies;
+		status = xs_sendpages(xprt->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;
+		if (likely(req->rq_bytes_sent >= req->rq_slen)) {
+			req->rq_bytes_sent = 0;
+			return 0;
+		}
+
+		status = -EAGAIN;
+		if (retry++ > XS_SENDMSG_RETRY)
+			break;
+	}
+
+	switch (status) {
+	case -EAGAIN:
+		xs_nospace(task);
+		break;
+	case -ECONNREFUSED:
+	case -ECONNRESET:
+	case -ENOTCONN:
+	case -EPIPE:
+		status = -ENOTCONN;
+		break;
+	default:
+		dprintk("RPC:      sendmsg returned unrecognized error %d\n",
+			-status);
+		xprt_disconnect(xprt);
+		break;
+	}
+
+	return status;
+}
+
+/**
+ * xs_close - close a socket
+ * @xprt: transport
+ *
+ * This is used when all requests are complete; ie, no DRC state remains
+ * on the server we want to save.
+ */
+static void xs_close(struct rpc_xprt *xprt)
+{
+	struct socket *sock = xprt->sock;
+	struct sock *sk = xprt->inet;
+
+	if (!sk)
+		return;
+
+	dprintk("RPC:      xs_close xprt %p\n", xprt);
+
+	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);
+}
+
+/**
+ * xs_destroy - prepare to shutdown a transport
+ * @xprt: doomed transport
+ *
+ */
+static void xs_destroy(struct rpc_xprt *xprt)
+{
+	dprintk("RPC:      xs_destroy xprt %p\n", xprt);
+
+	cancel_delayed_work(&xprt->connect_worker);
+	flush_scheduled_work();
+
+	xprt_disconnect(xprt);
+	xs_close(xprt);
+	kfree(xprt->slot);
+}
+
+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, *xp;
+
+	read_lock(&sk->sk_callback_lock);
+	dprintk("RPC:      xs_udp_data_ready...\n");
+	if (!(xprt = xprt_from_sock(sk)))
+		goto out;
+
+	if ((skb = skb_recv_datagram(sk, 0, 1, &err)) == NULL)
+		goto out;
+
+	if (xprt->shutdown)
+		goto dropit;
+
+	repsize = skb->len - sizeof(struct udphdr);
+	if (repsize < 4) {
+		dprintk("RPC:      impossible RPC reply size %d!\n", repsize);
+		goto dropit;
+	}
+
+	/* Copy the XID from the skb... */
+	xp = skb_header_pointer(skb, sizeof(struct udphdr),
+				sizeof(_xid), &_xid);
+	if (xp == NULL)
+		goto dropit;
+
+	/* Look up and lock the request corresponding to the given XID */
+	spin_lock(&xprt->transport_lock);
+	rovr = xprt_lookup_rqst(xprt, *xp);
+	if (!rovr)
+		goto out_unlock;
+	task = rovr->rq_task;
+
+	if ((copied = rovr->rq_private_buf.buflen) > repsize)
+		copied = repsize;
+
+	/* Suck it into the iovec, verify checksum if not done by hw. */
+	if (csum_partial_copy_to_xdr(&rovr->rq_private_buf, skb))
+		goto out_unlock;
+
+	/* Something worked... */
+	dst_confirm(skb->dst);
+
+	xprt_adjust_cwnd(task, copied);
+	xprt_update_rtt(task);
+	xprt_complete_rqst(task, copied);
+
+ out_unlock:
+	spin_unlock(&xprt->transport_lock);
+ dropit:
+	skb_free_datagram(sk, skb);
+ out:
+	read_unlock(&sk->sk_callback_lock);
+}
+
+static inline size_t xs_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;
+}
+
+static inline void xs_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 = xs_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 & RPC_LAST_STREAM_FRAGMENT)
+		xprt->tcp_flags |= XPRT_LAST_FRAG;
+	else
+		xprt->tcp_flags &= ~XPRT_LAST_FRAG;
+	xprt->tcp_reclen &= RPC_FRAGMENT_SIZE_MASK;
+
+	xprt->tcp_flags &= ~XPRT_COPY_RECM;
+	xprt->tcp_offset = 0;
+
+	/* Sanity check of the record length */
+	if (unlikely(xprt->tcp_reclen < 4)) {
+		dprintk("RPC:      invalid TCP record fragment length\n");
+		xprt_disconnect(xprt);
+		return;
+	}
+	dprintk("RPC:      reading TCP record fragment of length %d\n",
+			xprt->tcp_reclen);
+}
+
+static void xs_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;
+		}
+	}
+}
+
+static inline void xs_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 = xs_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));
+	xs_tcp_check_recm(xprt);
+}
+
+static inline void xs_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->transport_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->transport_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, xs_tcp_copy_data);
+		desc->count -= r;
+		desc->offset += r;
+	} else
+		r = xdr_partial_copy_from_skb(rcvbuf, xprt->tcp_copied,
+					  desc, xs_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))
+		xprt_complete_rqst(req->rq_task, xprt->tcp_copied);
+	spin_unlock(&xprt->transport_lock);
+	xs_tcp_check_recm(xprt);
+}
+
+static inline void xs_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);
+	xs_tcp_check_recm(xprt);
+}
+
+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;
+	skb_reader_t desc = {
+		.skb	= skb,
+		.offset	= offset,
+		.count	= len,
+		.csum	= 0
+	};
+
+	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 (xprt->tcp_flags & XPRT_COPY_RECM) {
+			xs_tcp_read_fraghdr(xprt, &desc);
+			continue;
+		}
+		/* Read in the xid if necessary */
+		if (xprt->tcp_flags & XPRT_COPY_XID) {
+			xs_tcp_read_xid(xprt, &desc);
+			continue;
+		}
+		/* Read in the request data */
+		if (xprt->tcp_flags & XPRT_COPY_DATA) {
+			xs_tcp_read_request(xprt, &desc);
+			continue;
+		}
+		/* Skip over any trailing bytes on short reads */
+		xs_tcp_read_discard(xprt, &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;
+
+	read_lock(&sk->sk_callback_lock);
+	dprintk("RPC:      xs_tcp_data_ready...\n");
+	if (!(xprt = xprt_from_sock(sk)))
+		goto out;
+	if (xprt->shutdown)
+		goto out;
+
+	/* We use rd_desc to pass struct xprt to xs_tcp_data_recv */
+	rd_desc.arg.data = xprt;
+	rd_desc.count = 65536;
+	tcp_read_sock(sk, &rd_desc, xs_tcp_data_recv);
+out:
+	read_unlock(&sk->sk_callback_lock);
+}
+
+/**
+ * xs_tcp_state_change - callback to handle TCP socket state changes
+ * @sk: socket whose state has changed
+ *
+ */
+static void xs_tcp_state_change(struct sock *sk)
+{
+	struct rpc_xprt *xprt;
+
+	read_lock(&sk->sk_callback_lock);
+	if (!(xprt = xprt_from_sock(sk)))
+		goto out;
+	dprintk("RPC:      xs_tcp_state_change client %p...\n", xprt);
+	dprintk("RPC:      state %x conn %d dead %d zapped %d\n",
+				sk->sk_state, xprt_connected(xprt),
+				sock_flag(sk, SOCK_DEAD),
+				sock_flag(sk, SOCK_ZAPPED));
+
+	switch (sk->sk_state) {
+	case TCP_ESTABLISHED:
+		spin_lock_bh(&xprt->transport_lock);
+		if (!xprt_test_and_set_connected(xprt)) {
+			/* 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;
+			xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
+			xprt_wake_pending_tasks(xprt, 0);
+		}
+		spin_unlock_bh(&xprt->transport_lock);
+		break;
+	case TCP_SYN_SENT:
+	case TCP_SYN_RECV:
+		break;
+	default:
+		xprt_disconnect(xprt);
+		break;
+	}
+ out:
+	read_unlock(&sk->sk_callback_lock);
+}
+
+/**
+ * xs_udp_write_space - callback invoked when socket buffer space
+ *                             becomes available
+ * @sk: socket whose state has changed
+ *
+ * Called when more output buffer space is available for this socket.
+ * We try not to wake our writers until they can make "significant"
+ * progress, otherwise we'll waste resources thrashing kernel_sendmsg
+ * with a bunch of small requests.
+ */
+static void xs_udp_write_space(struct sock *sk)
+{
+	read_lock(&sk->sk_callback_lock);
+
+	/* from net/core/sock.c:sock_def_write_space */
+	if (sock_writeable(sk)) {
+		struct socket *sock;
+		struct rpc_xprt *xprt;
+
+		if (unlikely(!(sock = sk->sk_socket)))
+			goto out;
+		if (unlikely(!(xprt = xprt_from_sock(sk))))
+			goto out;
+		if (unlikely(!test_and_clear_bit(SOCK_NOSPACE, &sock->flags)))
+			goto out;
+
+		xprt_write_space(xprt);
+	}
+
+ out:
+	read_unlock(&sk->sk_callback_lock);
+}
+
+/**
+ * xs_tcp_write_space - callback invoked when socket buffer space
+ *                             becomes available
+ * @sk: socket whose state has changed
+ *
+ * Called when more output buffer space is available for this socket.
+ * We try not to wake our writers until they can make "significant"
+ * progress, otherwise we'll waste resources thrashing kernel_sendmsg
+ * with a bunch of small requests.
+ */
+static void xs_tcp_write_space(struct sock *sk)
+{
+	read_lock(&sk->sk_callback_lock);
+
+	/* from net/core/stream.c:sk_stream_write_space */
+	if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
+		struct socket *sock;
+		struct rpc_xprt *xprt;
+
+		if (unlikely(!(sock = sk->sk_socket)))
+			goto out;
+		if (unlikely(!(xprt = xprt_from_sock(sk))))
+			goto out;
+		if (unlikely(!test_and_clear_bit(SOCK_NOSPACE, &sock->flags)))
+			goto out;
+
+		xprt_write_space(xprt);
+	}
+
+ out:
+	read_unlock(&sk->sk_callback_lock);
+}
+
+static void xs_udp_do_set_buffer_size(struct rpc_xprt *xprt)
+{
+	struct sock *sk = xprt->inet;
+
+	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);
+	}
+}
+
+/**
+ * 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)
+{
+	xprt->sndsize = 0;
+	if (sndsize)
+		xprt->sndsize = sndsize + 1024;
+	xprt->rcvsize = 0;
+	if (rcvsize)
+		xprt->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 int xs_bindresvport(struct rpc_xprt *xprt, struct socket *sock)
+{
+	struct sockaddr_in myaddr = {
+		.sin_family = AF_INET,
+	};
+	int err;
+	unsigned short 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;
+			dprintk("RPC:      xs_bindresvport bound to port %u\n",
+					port);
+			return 0;
+		}
+		if (port <= xprt_min_resvport)
+			port = xprt_max_resvport;
+		else
+			port--;
+	} while (err == -EADDRINUSE && port != xprt->port);
+
+	dprintk("RPC:      can't bind to reserved port (%d).\n", -err);
+	return err;
+}
+
+/**
+ * xs_udp_connect_worker - set up a UDP socket
+ * @args: RPC transport to connect
+ *
+ * Invoked by a work queue tasklet.
+ */
+static void xs_udp_connect_worker(void *args)
+{
+	struct rpc_xprt *xprt = (struct rpc_xprt *) args;
+	struct socket *sock = xprt->sock;
+	int err, status = -EIO;
+
+	if (xprt->shutdown || xprt->addr.sin_port == 0)
+		goto out;
+
+	dprintk("RPC:      xs_udp_connect_worker for xprt %p\n", xprt);
+
+	/* Start by resetting any existing state */
+	xs_close(xprt);
+
+	if ((err = sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock)) < 0) {
+		dprintk("RPC:      can't create UDP transport socket (%d).\n", -err);
+		goto out;
+	}
+
+	if (xprt->resvport && xs_bindresvport(xprt, sock) < 0) {
+		sock_release(sock);
+		goto out;
+	}
+
+	if (!xprt->inet) {
+		struct sock *sk = sock->sk;
+
+		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;
+		sk->sk_data_ready = xs_udp_data_ready;
+		sk->sk_write_space = xs_udp_write_space;
+		sk->sk_no_check = UDP_CSUM_NORCV;
+
+		xprt_set_connected(xprt);
+
+		/* Reset to new socket */
+		xprt->sock = sock;
+		xprt->inet = sk;
+
+		write_unlock_bh(&sk->sk_callback_lock);
+	}
+	xs_udp_do_set_buffer_size(xprt);
+	status = 0;
+out:
+	xprt_wake_pending_tasks(xprt, status);
+	xprt_clear_connecting(xprt);
+}
+
+/*
+ * We need to preserve the port number so the reply cache on the server can
+ * find our cached RPC replies when we get around to reconnecting.
+ */
+static void xs_tcp_reuse_connection(struct rpc_xprt *xprt)
+{
+	int result;
+	struct socket *sock = xprt->sock;
+	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 = sock->ops->connect(sock, &any, sizeof(any), 0);
+	if (result)
+		dprintk("RPC:      AF_UNSPEC connect return code %d\n",
+				result);
+}
+
+/**
+ * xs_tcp_connect_worker - connect a TCP socket to a remote endpoint
+ * @args: RPC transport to connect
+ *
+ * Invoked by a work queue tasklet.
+ */
+static void xs_tcp_connect_worker(void *args)
+{
+	struct rpc_xprt *xprt = (struct rpc_xprt *)args;
+	struct socket *sock = xprt->sock;
+	int err, status = -EIO;
+
+	if (xprt->shutdown || xprt->addr.sin_port == 0)
+		goto out;
+
+	dprintk("RPC:      xs_tcp_connect_worker for xprt %p\n", xprt);
+
+	if (!xprt->sock) {
+		/* start from scratch */
+		if ((err = sock_create_kern(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock)) < 0) {
+			dprintk("RPC:      can't create TCP transport socket (%d).\n", -err);
+			goto out;
+		}
+
+		if (xprt->resvport && xs_bindresvport(xprt, sock) < 0) {
+			sock_release(sock);
+			goto out;
+		}
+	} else
+		/* "close" the socket, preserving the local port */
+		xs_tcp_reuse_connection(xprt);
+
+	if (!xprt->inet) {
+		struct sock *sk = sock->sk;
+
+		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;
+		sk->sk_data_ready = xs_tcp_data_ready;
+		sk->sk_state_change = xs_tcp_state_change;
+		sk->sk_write_space = xs_tcp_write_space;
+
+		/* 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 */
+		xprt->sock = sock;
+		xprt->inet = sk;
+
+		write_unlock_bh(&sk->sk_callback_lock);
+	}
+
+	/* 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;
+			case -ECONNREFUSED:
+			case -ECONNRESET:
+				/* retry with existing socket, after a delay */
+				break;
+			default:
+				/* get rid of existing socket, and retry */
+				xs_close(xprt);
+				break;
+		}
+	}
+out:
+	xprt_wake_pending_tasks(xprt, status);
+out_clear:
+	xprt_clear_connecting(xprt);
+}
+
+/**
+ * xs_connect - connect a socket to a remote endpoint
+ * @task: address of RPC task that manages state of connect request
+ *
+ * TCP: If the remote end dropped the connection, delay reconnecting.
+ *
+ * UDP socket connects are synchronous, but we use a work queue anyway
+ * to guarantee that even unprivileged user processes can set up a
+ * socket on a privileged port.
+ *
+ * If a UDP socket connect fails, the delay behavior here prevents
+ * retry floods (hard mounts).
+ */
+static void xs_connect(struct rpc_task *task)
+{
+	struct rpc_xprt *xprt = task->tk_xprt;
+
+	if (xprt_test_and_set_connecting(xprt))
+		return;
+
+	if (xprt->sock != NULL) {
+		dprintk("RPC:      xs_connect delayed xprt %p for %lu seconds\n",
+				xprt, xprt->reestablish_timeout / HZ);
+		schedule_delayed_work(&xprt->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);
+		schedule_work(&xprt->connect_worker);
+
+		/* flush_scheduled_work can sleep... */
+		if (!RPC_IS_ASYNC(task))
+			flush_scheduled_work();
+	}
+}
+
+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,
+	.connect		= xs_connect,
+	.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,
+};
+
+static struct rpc_xprt_ops xs_tcp_ops = {
+	.reserve_xprt		= xprt_reserve_xprt,
+	.release_xprt		= xprt_release_xprt,
+	.connect		= xs_connect,
+	.send_request		= xs_tcp_send_request,
+	.set_retrans_timeout	= xprt_set_retrans_timeout_def,
+	.close			= xs_close,
+	.destroy		= xs_destroy,
+};
+
+/**
+ * xs_setup_udp - Set up transport to use a UDP socket
+ * @xprt: transport to set up
+ * @to:   timeout parameters
+ *
+ */
+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->tsh_size = 0;
+	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->connect_worker, xs_udp_connect_worker, xprt);
+	xprt->bind_timeout = XS_BIND_TO;
+	xprt->connect_timeout = XS_UDP_CONN_TO;
+	xprt->reestablish_timeout = XS_UDP_REEST_TO;
+	xprt->idle_timeout = XS_IDLE_DISC_TO;
+
+	xprt->ops = &xs_udp_ops;
+
+	if (to)
+		xprt->timeout = *to;
+	else
+		xprt_set_timeout(&xprt->timeout, 5, 5 * HZ);
+
+	return 0;
+}
+
+/**
+ * xs_setup_tcp - Set up transport to use a TCP socket
+ * @xprt: transport to set up
+ * @to: timeout parameters
+ *
+ */
+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->tsh_size = sizeof(rpc_fraghdr) / sizeof(u32);
+	xprt->resvport = capable(CAP_NET_BIND_SERVICE) ? 1 : 0;
+	xprt->max_payload = RPC_MAX_FRAGMENT_SIZE;
+
+	INIT_WORK(&xprt->connect_worker, xs_tcp_connect_worker, xprt);
+	xprt->bind_timeout = XS_BIND_TO;
+	xprt->connect_timeout = XS_TCP_CONN_TO;
+	xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
+	xprt->idle_timeout = XS_IDLE_DISC_TO;
+
+	xprt->ops = &xs_tcp_ops;
+
+	if (to)
+		xprt->timeout = *to;
+	else
+		xprt_set_timeout(&xprt->timeout, 2, 60 * HZ);
+
+	return 0;
+}