svc: Move the xprt independent code to the svc_xprt.c file

This functionally trivial patch moves all of the transport independent
functions from the svcsock.c file to the transport independent svc_xprt.c
file.

In addition the following formatting changes were made:
- White space cleanup
- Function signatures on single line
- The inline directive was removed
- Lines over 80 columns were reformatted
- The term 'socket' was changed to 'transport' in comments
- The SMP comment was moved and updated.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Acked-by: Neil Brown <neilb@suse.de>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Greg Banks <gnb@sgi.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 753 insertions, 0 deletions

diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 271467c..23165ae 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -35,10 +35,53 @@
 
 #define RPCDBG_FACILITY	RPCDBG_SVCXPRT
 
+static struct svc_deferred_req *svc_deferred_dequeue(struct svc_xprt *xprt);
+static int svc_deferred_recv(struct svc_rqst *rqstp);
+static struct cache_deferred_req *svc_defer(struct cache_req *req);
+static void svc_age_temp_xprts(unsigned long closure);
+
+/* apparently the "standard" is that clients close
+ * idle connections after 5 minutes, servers after
+ * 6 minutes
+ *   http://www.connectathon.org/talks96/nfstcp.pdf
+ */
+static int svc_conn_age_period = 6*60;
+
 /* List of registered transport classes */
 static DEFINE_SPINLOCK(svc_xprt_class_lock);
 static LIST_HEAD(svc_xprt_class_list);
 
+/* SMP locking strategy:
+ *
+ *	svc_pool->sp_lock protects most of the fields of that pool.
+ *	svc_serv->sv_lock protects sv_tempsocks, sv_permsocks, sv_tmpcnt.
+ *	when both need to be taken (rare), svc_serv->sv_lock is first.
+ *	BKL protects svc_serv->sv_nrthread.
+ *	svc_sock->sk_lock protects the svc_sock->sk_deferred list
+ *             and the ->sk_info_authunix cache.
+ *
+ *	The XPT_BUSY bit in xprt->xpt_flags prevents a transport being
+ *	enqueued multiply. During normal transport processing this bit
+ *	is set by svc_xprt_enqueue and cleared by svc_xprt_received.
+ *	Providers should not manipulate this bit directly.
+ *
+ *	Some flags can be set to certain values at any time
+ *	providing that certain rules are followed:
+ *
+ *	XPT_CONN, XPT_DATA:
+ *		- Can be set or cleared at any time.
+ *		- After a set, svc_xprt_enqueue must be called to enqueue
+ *		  the transport for processing.
+ *		- After a clear, the transport must be read/accepted.
+ *		  If this succeeds, it must be set again.
+ *	XPT_CLOSE:
+ *		- Can set at any time. It is never cleared.
+ *      XPT_DEAD:
+ *		- Can only be set while XPT_BUSY is held which ensures
+ *		  that no other thread will be using the transport or will
+ *		  try to set XPT_DEAD.
+ */
+
 int svc_reg_xprt_class(struct svc_xprt_class *xcl)
 {
 	struct svc_xprt_class *cl;
@@ -178,3 +221,713 @@ void svc_xprt_copy_addrs(struct svc_rqst *rqstp, struct svc_xprt *xprt)
 }
 EXPORT_SYMBOL_GPL(svc_xprt_copy_addrs);
 
+/**
+ * svc_print_addr - Format rq_addr field for printing
+ * @rqstp: svc_rqst struct containing address to print
+ * @buf: target buffer for formatted address
+ * @len: length of target buffer
+ *
+ */
+char *svc_print_addr(struct svc_rqst *rqstp, char *buf, size_t len)
+{
+	return __svc_print_addr(svc_addr(rqstp), buf, len);
+}
+EXPORT_SYMBOL_GPL(svc_print_addr);
+
+/*
+ * Queue up an idle server thread.  Must have pool->sp_lock held.
+ * Note: this is really a stack rather than a queue, so that we only
+ * use as many different threads as we need, and the rest don't pollute
+ * the cache.
+ */
+static void svc_thread_enqueue(struct svc_pool *pool, struct svc_rqst *rqstp)
+{
+	list_add(&rqstp->rq_list, &pool->sp_threads);
+}
+
+/*
+ * Dequeue an nfsd thread.  Must have pool->sp_lock held.
+ */
+static void svc_thread_dequeue(struct svc_pool *pool, struct svc_rqst *rqstp)
+{
+	list_del(&rqstp->rq_list);
+}
+
+/*
+ * Queue up a transport with data pending. If there are idle nfsd
+ * processes, wake 'em up.
+ *
+ */
+void svc_xprt_enqueue(struct svc_xprt *xprt)
+{
+	struct svc_serv	*serv = xprt->xpt_server;
+	struct svc_pool *pool;
+	struct svc_rqst	*rqstp;
+	int cpu;
+
+	if (!(xprt->xpt_flags &
+	      ((1<<XPT_CONN)|(1<<XPT_DATA)|(1<<XPT_CLOSE)|(1<<XPT_DEFERRED))))
+		return;
+	if (test_bit(XPT_DEAD, &xprt->xpt_flags))
+		return;
+
+	cpu = get_cpu();
+	pool = svc_pool_for_cpu(xprt->xpt_server, cpu);
+	put_cpu();
+
+	spin_lock_bh(&pool->sp_lock);
+
+	if (!list_empty(&pool->sp_threads) &&
+	    !list_empty(&pool->sp_sockets))
+		printk(KERN_ERR
+		       "svc_xprt_enqueue: "
+		       "threads and transports both waiting??\n");
+
+	if (test_bit(XPT_DEAD, &xprt->xpt_flags)) {
+		/* Don't enqueue dead transports */
+		dprintk("svc: transport %p is dead, not enqueued\n", xprt);
+		goto out_unlock;
+	}
+
+	/* Mark transport as busy. It will remain in this state until
+	 * the provider calls svc_xprt_received. We update XPT_BUSY
+	 * atomically because it also guards against trying to enqueue
+	 * the transport twice.
+	 */
+	if (test_and_set_bit(XPT_BUSY, &xprt->xpt_flags)) {
+		/* Don't enqueue transport while already enqueued */
+		dprintk("svc: transport %p busy, not enqueued\n", xprt);
+		goto out_unlock;
+	}
+	BUG_ON(xprt->xpt_pool != NULL);
+	xprt->xpt_pool = pool;
+
+	/* Handle pending connection */
+	if (test_bit(XPT_CONN, &xprt->xpt_flags))
+		goto process;
+
+	/* Handle close in-progress */
+	if (test_bit(XPT_CLOSE, &xprt->xpt_flags))
+		goto process;
+
+	/* Check if we have space to reply to a request */
+	if (!xprt->xpt_ops->xpo_has_wspace(xprt)) {
+		/* Don't enqueue while not enough space for reply */
+		dprintk("svc: no write space, transport %p  not enqueued\n",
+			xprt);
+		xprt->xpt_pool = NULL;
+		clear_bit(XPT_BUSY, &xprt->xpt_flags);
+		goto out_unlock;
+	}
+
+ process:
+	if (!list_empty(&pool->sp_threads)) {
+		rqstp = list_entry(pool->sp_threads.next,
+				   struct svc_rqst,
+				   rq_list);
+		dprintk("svc: transport %p served by daemon %p\n",
+			xprt, rqstp);
+		svc_thread_dequeue(pool, rqstp);
+		if (rqstp->rq_xprt)
+			printk(KERN_ERR
+				"svc_xprt_enqueue: server %p, rq_xprt=%p!\n",
+				rqstp, rqstp->rq_xprt);
+		rqstp->rq_xprt = xprt;
+		svc_xprt_get(xprt);
+		rqstp->rq_reserved = serv->sv_max_mesg;
+		atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved);
+		BUG_ON(xprt->xpt_pool != pool);
+		wake_up(&rqstp->rq_wait);
+	} else {
+		dprintk("svc: transport %p put into queue\n", xprt);
+		list_add_tail(&xprt->xpt_ready, &pool->sp_sockets);
+		BUG_ON(xprt->xpt_pool != pool);
+	}
+
+out_unlock:
+	spin_unlock_bh(&pool->sp_lock);
+}
+EXPORT_SYMBOL_GPL(svc_xprt_enqueue);
+
+/*
+ * Dequeue the first transport.  Must be called with the pool->sp_lock held.
+ */
+static struct svc_xprt *svc_xprt_dequeue(struct svc_pool *pool)
+{
+	struct svc_xprt	*xprt;
+
+	if (list_empty(&pool->sp_sockets))
+		return NULL;
+
+	xprt = list_entry(pool->sp_sockets.next,
+			  struct svc_xprt, xpt_ready);
+	list_del_init(&xprt->xpt_ready);
+
+	dprintk("svc: transport %p dequeued, inuse=%d\n",
+		xprt, atomic_read(&xprt->xpt_ref.refcount));
+
+	return xprt;
+}
+
+/*
+ * svc_xprt_received conditionally queues the transport for processing
+ * by another thread. The caller must hold the XPT_BUSY bit and must
+ * not thereafter touch transport data.
+ *
+ * Note: XPT_DATA only gets cleared when a read-attempt finds no (or
+ * insufficient) data.
+ */
+void svc_xprt_received(struct svc_xprt *xprt)
+{
+	BUG_ON(!test_bit(XPT_BUSY, &xprt->xpt_flags));
+	xprt->xpt_pool = NULL;
+	clear_bit(XPT_BUSY, &xprt->xpt_flags);
+	svc_xprt_enqueue(xprt);
+}
+EXPORT_SYMBOL_GPL(svc_xprt_received);
+
+/**
+ * svc_reserve - change the space reserved for the reply to a request.
+ * @rqstp:  The request in question
+ * @space: new max space to reserve
+ *
+ * Each request reserves some space on the output queue of the transport
+ * to make sure the reply fits.  This function reduces that reserved
+ * space to be the amount of space used already, plus @space.
+ *
+ */
+void svc_reserve(struct svc_rqst *rqstp, int space)
+{
+	space += rqstp->rq_res.head[0].iov_len;
+
+	if (space < rqstp->rq_reserved) {
+		struct svc_xprt *xprt = rqstp->rq_xprt;
+		atomic_sub((rqstp->rq_reserved - space), &xprt->xpt_reserved);
+		rqstp->rq_reserved = space;
+
+		svc_xprt_enqueue(xprt);
+	}
+}
+
+static void svc_xprt_release(struct svc_rqst *rqstp)
+{
+	struct svc_xprt	*xprt = rqstp->rq_xprt;
+
+	rqstp->rq_xprt->xpt_ops->xpo_release_rqst(rqstp);
+
+	svc_free_res_pages(rqstp);
+	rqstp->rq_res.page_len = 0;
+	rqstp->rq_res.page_base = 0;
+
+	/* Reset response buffer and release
+	 * the reservation.
+	 * But first, check that enough space was reserved
+	 * for the reply, otherwise we have a bug!
+	 */
+	if ((rqstp->rq_res.len) >  rqstp->rq_reserved)
+		printk(KERN_ERR "RPC request reserved %d but used %d\n",
+		       rqstp->rq_reserved,
+		       rqstp->rq_res.len);
+
+	rqstp->rq_res.head[0].iov_len = 0;
+	svc_reserve(rqstp, 0);
+	rqstp->rq_xprt = NULL;
+
+	svc_xprt_put(xprt);
+}
+
+/*
+ * External function to wake up a server waiting for data
+ * This really only makes sense for services like lockd
+ * which have exactly one thread anyway.
+ */
+void svc_wake_up(struct svc_serv *serv)
+{
+	struct svc_rqst	*rqstp;
+	unsigned int i;
+	struct svc_pool *pool;
+
+	for (i = 0; i < serv->sv_nrpools; i++) {
+		pool = &serv->sv_pools[i];
+
+		spin_lock_bh(&pool->sp_lock);
+		if (!list_empty(&pool->sp_threads)) {
+			rqstp = list_entry(pool->sp_threads.next,
+					   struct svc_rqst,
+					   rq_list);
+			dprintk("svc: daemon %p woken up.\n", rqstp);
+			/*
+			svc_thread_dequeue(pool, rqstp);
+			rqstp->rq_xprt = NULL;
+			 */
+			wake_up(&rqstp->rq_wait);
+		}
+		spin_unlock_bh(&pool->sp_lock);
+	}
+}
+
+int svc_port_is_privileged(struct sockaddr *sin)
+{
+	switch (sin->sa_family) {
+	case AF_INET:
+		return ntohs(((struct sockaddr_in *)sin)->sin_port)
+			< PROT_SOCK;
+	case AF_INET6:
+		return ntohs(((struct sockaddr_in6 *)sin)->sin6_port)
+			< PROT_SOCK;
+	default:
+		return 0;
+	}
+}
+
+/*
+ * Make sure that we don't have too many active connections.  If we
+ * have, something must be dropped.
+ *
+ * There's no point in trying to do random drop here for DoS
+ * prevention. The NFS clients does 1 reconnect in 15 seconds. An
+ * attacker can easily beat that.
+ *
+ * The only somewhat efficient mechanism would be if drop old
+ * connections from the same IP first. But right now we don't even
+ * record the client IP in svc_sock.
+ */
+static void svc_check_conn_limits(struct svc_serv *serv)
+{
+	if (serv->sv_tmpcnt > (serv->sv_nrthreads+3)*20) {
+		struct svc_xprt *xprt = NULL;
+		spin_lock_bh(&serv->sv_lock);
+		if (!list_empty(&serv->sv_tempsocks)) {
+			if (net_ratelimit()) {
+				/* Try to help the admin */
+				printk(KERN_NOTICE "%s: too many open  "
+				       "connections, consider increasing the "
+				       "number of nfsd threads\n",
+				       serv->sv_name);
+			}
+			/*
+			 * Always select the oldest connection. It's not fair,
+			 * but so is life
+			 */
+			xprt = list_entry(serv->sv_tempsocks.prev,
+					  struct svc_xprt,
+					  xpt_list);
+			set_bit(XPT_CLOSE, &xprt->xpt_flags);
+			svc_xprt_get(xprt);
+		}
+		spin_unlock_bh(&serv->sv_lock);
+
+		if (xprt) {
+			svc_xprt_enqueue(xprt);
+			svc_xprt_put(xprt);
+		}
+	}
+}
+
+/*
+ * Receive the next request on any transport.  This code is carefully
+ * organised not to touch any cachelines in the shared svc_serv
+ * structure, only cachelines in the local svc_pool.
+ */
+int svc_recv(struct svc_rqst *rqstp, long timeout)
+{
+	struct svc_xprt		*xprt = NULL;
+	struct svc_serv		*serv = rqstp->rq_server;
+	struct svc_pool		*pool = rqstp->rq_pool;
+	int			len, i;
+	int			pages;
+	struct xdr_buf		*arg;
+	DECLARE_WAITQUEUE(wait, current);
+
+	dprintk("svc: server %p waiting for data (to = %ld)\n",
+		rqstp, timeout);
+
+	if (rqstp->rq_xprt)
+		printk(KERN_ERR
+			"svc_recv: service %p, transport not NULL!\n",
+			 rqstp);
+	if (waitqueue_active(&rqstp->rq_wait))
+		printk(KERN_ERR
+			"svc_recv: service %p, wait queue active!\n",
+			 rqstp);
+
+	/* now allocate needed pages.  If we get a failure, sleep briefly */
+	pages = (serv->sv_max_mesg + PAGE_SIZE) / PAGE_SIZE;
+	for (i = 0; i < pages ; i++)
+		while (rqstp->rq_pages[i] == NULL) {
+			struct page *p = alloc_page(GFP_KERNEL);
+			if (!p) {
+				int j = msecs_to_jiffies(500);
+				schedule_timeout_uninterruptible(j);
+			}
+			rqstp->rq_pages[i] = p;
+		}
+	rqstp->rq_pages[i++] = NULL; /* this might be seen in nfs_read_actor */
+	BUG_ON(pages >= RPCSVC_MAXPAGES);
+
+	/* Make arg->head point to first page and arg->pages point to rest */
+	arg = &rqstp->rq_arg;
+	arg->head[0].iov_base = page_address(rqstp->rq_pages[0]);
+	arg->head[0].iov_len = PAGE_SIZE;
+	arg->pages = rqstp->rq_pages + 1;
+	arg->page_base = 0;
+	/* save at least one page for response */
+	arg->page_len = (pages-2)*PAGE_SIZE;
+	arg->len = (pages-1)*PAGE_SIZE;
+	arg->tail[0].iov_len = 0;
+
+	try_to_freeze();
+	cond_resched();
+	if (signalled())
+		return -EINTR;
+
+	spin_lock_bh(&pool->sp_lock);
+	xprt = svc_xprt_dequeue(pool);
+	if (xprt) {
+		rqstp->rq_xprt = xprt;
+		svc_xprt_get(xprt);
+		rqstp->rq_reserved = serv->sv_max_mesg;
+		atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved);
+	} else {
+		/* No data pending. Go to sleep */
+		svc_thread_enqueue(pool, rqstp);
+
+		/*
+		 * We have to be able to interrupt this wait
+		 * to bring down the daemons ...
+		 */
+		set_current_state(TASK_INTERRUPTIBLE);
+		add_wait_queue(&rqstp->rq_wait, &wait);
+		spin_unlock_bh(&pool->sp_lock);
+
+		schedule_timeout(timeout);
+
+		try_to_freeze();
+
+		spin_lock_bh(&pool->sp_lock);
+		remove_wait_queue(&rqstp->rq_wait, &wait);
+
+		xprt = rqstp->rq_xprt;
+		if (!xprt) {
+			svc_thread_dequeue(pool, rqstp);
+			spin_unlock_bh(&pool->sp_lock);
+			dprintk("svc: server %p, no data yet\n", rqstp);
+			return signalled()? -EINTR : -EAGAIN;
+		}
+	}
+	spin_unlock_bh(&pool->sp_lock);
+
+	len = 0;
+	if (test_bit(XPT_CLOSE, &xprt->xpt_flags)) {
+		dprintk("svc_recv: found XPT_CLOSE\n");
+		svc_delete_xprt(xprt);
+	} else if (test_bit(XPT_LISTENER, &xprt->xpt_flags)) {
+		struct svc_xprt *newxpt;
+		newxpt = xprt->xpt_ops->xpo_accept(xprt);
+		if (newxpt) {
+			/*
+			 * We know this module_get will succeed because the
+			 * listener holds a reference too
+			 */
+			__module_get(newxpt->xpt_class->xcl_owner);
+			svc_check_conn_limits(xprt->xpt_server);
+			spin_lock_bh(&serv->sv_lock);
+			set_bit(XPT_TEMP, &newxpt->xpt_flags);
+			list_add(&newxpt->xpt_list, &serv->sv_tempsocks);
+			serv->sv_tmpcnt++;
+			if (serv->sv_temptimer.function == NULL) {
+				/* setup timer to age temp transports */
+				setup_timer(&serv->sv_temptimer,
+					    svc_age_temp_xprts,
+					    (unsigned long)serv);
+				mod_timer(&serv->sv_temptimer,
+					  jiffies + svc_conn_age_period * HZ);
+			}
+			spin_unlock_bh(&serv->sv_lock);
+			svc_xprt_received(newxpt);
+		}
+		svc_xprt_received(xprt);
+	} else {
+		dprintk("svc: server %p, pool %u, transport %p, inuse=%d\n",
+			rqstp, pool->sp_id, xprt,
+			atomic_read(&xprt->xpt_ref.refcount));
+		rqstp->rq_deferred = svc_deferred_dequeue(xprt);
+		if (rqstp->rq_deferred) {
+			svc_xprt_received(xprt);
+			len = svc_deferred_recv(rqstp);
+		} else
+			len = xprt->xpt_ops->xpo_recvfrom(rqstp);
+		dprintk("svc: got len=%d\n", len);
+	}
+
+	/* No data, incomplete (TCP) read, or accept() */
+	if (len == 0 || len == -EAGAIN) {
+		rqstp->rq_res.len = 0;
+		svc_xprt_release(rqstp);
+		return -EAGAIN;
+	}
+	clear_bit(XPT_OLD, &xprt->xpt_flags);
+
+	rqstp->rq_secure = svc_port_is_privileged(svc_addr(rqstp));
+	rqstp->rq_chandle.defer = svc_defer;
+
+	if (serv->sv_stats)
+		serv->sv_stats->netcnt++;
+	return len;
+}
+
+/*
+ * Drop request
+ */
+void svc_drop(struct svc_rqst *rqstp)
+{
+	dprintk("svc: xprt %p dropped request\n", rqstp->rq_xprt);
+	svc_xprt_release(rqstp);
+}
+
+/*
+ * Return reply to client.
+ */
+int svc_send(struct svc_rqst *rqstp)
+{
+	struct svc_xprt	*xprt;
+	int		len;
+	struct xdr_buf	*xb;
+
+	xprt = rqstp->rq_xprt;
+	if (!xprt)
+		return -EFAULT;
+
+	/* release the receive skb before sending the reply */
+	rqstp->rq_xprt->xpt_ops->xpo_release_rqst(rqstp);
+
+	/* calculate over-all length */
+	xb = &rqstp->rq_res;
+	xb->len = xb->head[0].iov_len +
+		xb->page_len +
+		xb->tail[0].iov_len;
+
+	/* Grab mutex to serialize outgoing data. */
+	mutex_lock(&xprt->xpt_mutex);
+	if (test_bit(XPT_DEAD, &xprt->xpt_flags))
+		len = -ENOTCONN;
+	else
+		len = xprt->xpt_ops->xpo_sendto(rqstp);
+	mutex_unlock(&xprt->xpt_mutex);
+	svc_xprt_release(rqstp);
+
+	if (len == -ECONNREFUSED || len == -ENOTCONN || len == -EAGAIN)
+		return 0;
+	return len;
+}
+
+/*
+ * Timer function to close old temporary transports, using
+ * a mark-and-sweep algorithm.
+ */
+static void svc_age_temp_xprts(unsigned long closure)
+{
+	struct svc_serv *serv = (struct svc_serv *)closure;
+	struct svc_xprt *xprt;
+	struct list_head *le, *next;
+	LIST_HEAD(to_be_aged);
+
+	dprintk("svc_age_temp_xprts\n");
+
+	if (!spin_trylock_bh(&serv->sv_lock)) {
+		/* busy, try again 1 sec later */
+		dprintk("svc_age_temp_xprts: busy\n");
+		mod_timer(&serv->sv_temptimer, jiffies + HZ);
+		return;
+	}
+
+	list_for_each_safe(le, next, &serv->sv_tempsocks) {
+		xprt = list_entry(le, struct svc_xprt, xpt_list);
+
+		/* First time through, just mark it OLD. Second time
+		 * through, close it. */
+		if (!test_and_set_bit(XPT_OLD, &xprt->xpt_flags))
+			continue;
+		if (atomic_read(&xprt->xpt_ref.refcount) > 1
+		    || test_bit(XPT_BUSY, &xprt->xpt_flags))
+			continue;
+		svc_xprt_get(xprt);
+		list_move(le, &to_be_aged);
+		set_bit(XPT_CLOSE, &xprt->xpt_flags);
+		set_bit(XPT_DETACHED, &xprt->xpt_flags);
+	}
+	spin_unlock_bh(&serv->sv_lock);
+
+	while (!list_empty(&to_be_aged)) {
+		le = to_be_aged.next;
+		/* fiddling the xpt_list node is safe 'cos we're XPT_DETACHED */
+		list_del_init(le);
+		xprt = list_entry(le, struct svc_xprt, xpt_list);
+
+		dprintk("queuing xprt %p for closing\n", xprt);
+
+		/* a thread will dequeue and close it soon */
+		svc_xprt_enqueue(xprt);
+		svc_xprt_put(xprt);
+	}
+
+	mod_timer(&serv->sv_temptimer, jiffies + svc_conn_age_period * HZ);
+}
+
+/*
+ * Remove a dead transport
+ */
+void svc_delete_xprt(struct svc_xprt *xprt)
+{
+	struct svc_serv	*serv = xprt->xpt_server;
+
+	dprintk("svc: svc_delete_xprt(%p)\n", xprt);
+	xprt->xpt_ops->xpo_detach(xprt);
+
+	spin_lock_bh(&serv->sv_lock);
+	if (!test_and_set_bit(XPT_DETACHED, &xprt->xpt_flags))
+		list_del_init(&xprt->xpt_list);
+	/*
+	 * We used to delete the transport from whichever list
+	 * it's sk_xprt.xpt_ready node was on, but we don't actually
+	 * need to.  This is because the only time we're called
+	 * while still attached to a queue, the queue itself
+	 * is about to be destroyed (in svc_destroy).
+	 */
+	if (!test_and_set_bit(XPT_DEAD, &xprt->xpt_flags)) {
+		BUG_ON(atomic_read(&xprt->xpt_ref.refcount) < 2);
+		if (test_bit(XPT_TEMP, &xprt->xpt_flags))
+			serv->sv_tmpcnt--;
+		svc_xprt_put(xprt);
+	}
+	spin_unlock_bh(&serv->sv_lock);
+}
+
+void svc_close_xprt(struct svc_xprt *xprt)
+{
+	set_bit(XPT_CLOSE, &xprt->xpt_flags);
+	if (test_and_set_bit(XPT_BUSY, &xprt->xpt_flags))
+		/* someone else will have to effect the close */
+		return;
+
+	svc_xprt_get(xprt);
+	svc_delete_xprt(xprt);
+	clear_bit(XPT_BUSY, &xprt->xpt_flags);
+	svc_xprt_put(xprt);
+}
+
+void svc_close_all(struct list_head *xprt_list)
+{
+	struct svc_xprt *xprt;
+	struct svc_xprt *tmp;
+
+	list_for_each_entry_safe(xprt, tmp, xprt_list, xpt_list) {
+		set_bit(XPT_CLOSE, &xprt->xpt_flags);
+		if (test_bit(XPT_BUSY, &xprt->xpt_flags)) {
+			/* Waiting to be processed, but no threads left,
+			 * So just remove it from the waiting list
+			 */
+			list_del_init(&xprt->xpt_ready);
+			clear_bit(XPT_BUSY, &xprt->xpt_flags);
+		}
+		svc_close_xprt(xprt);
+	}
+}
+
+/*
+ * Handle defer and revisit of requests
+ */
+
+static void svc_revisit(struct cache_deferred_req *dreq, int too_many)
+{
+	struct svc_deferred_req *dr =
+		container_of(dreq, struct svc_deferred_req, handle);
+	struct svc_xprt *xprt = dr->xprt;
+
+	if (too_many) {
+		svc_xprt_put(xprt);
+		kfree(dr);
+		return;
+	}
+	dprintk("revisit queued\n");
+	dr->xprt = NULL;
+	spin_lock(&xprt->xpt_lock);
+	list_add(&dr->handle.recent, &xprt->xpt_deferred);
+	spin_unlock(&xprt->xpt_lock);
+	set_bit(XPT_DEFERRED, &xprt->xpt_flags);
+	svc_xprt_enqueue(xprt);
+	svc_xprt_put(xprt);
+}
+
+static struct cache_deferred_req *svc_defer(struct cache_req *req)
+{
+	struct svc_rqst *rqstp = container_of(req, struct svc_rqst, rq_chandle);
+	int size = sizeof(struct svc_deferred_req) + (rqstp->rq_arg.len);
+	struct svc_deferred_req *dr;
+
+	if (rqstp->rq_arg.page_len)
+		return NULL; /* if more than a page, give up FIXME */
+	if (rqstp->rq_deferred) {
+		dr = rqstp->rq_deferred;
+		rqstp->rq_deferred = NULL;
+	} else {
+		int skip  = rqstp->rq_arg.len - rqstp->rq_arg.head[0].iov_len;
+		/* FIXME maybe discard if size too large */
+		dr = kmalloc(size, GFP_KERNEL);
+		if (dr == NULL)
+			return NULL;
+
+		dr->handle.owner = rqstp->rq_server;
+		dr->prot = rqstp->rq_prot;
+		memcpy(&dr->addr, &rqstp->rq_addr, rqstp->rq_addrlen);
+		dr->addrlen = rqstp->rq_addrlen;
+		dr->daddr = rqstp->rq_daddr;
+		dr->argslen = rqstp->rq_arg.len >> 2;
+		memcpy(dr->args, rqstp->rq_arg.head[0].iov_base-skip,
+		       dr->argslen<<2);
+	}
+	svc_xprt_get(rqstp->rq_xprt);
+	dr->xprt = rqstp->rq_xprt;
+
+	dr->handle.revisit = svc_revisit;
+	return &dr->handle;
+}
+
+/*
+ * recv data from a deferred request into an active one
+ */
+static int svc_deferred_recv(struct svc_rqst *rqstp)
+{
+	struct svc_deferred_req *dr = rqstp->rq_deferred;
+
+	rqstp->rq_arg.head[0].iov_base = dr->args;
+	rqstp->rq_arg.head[0].iov_len = dr->argslen<<2;
+	rqstp->rq_arg.page_len = 0;
+	rqstp->rq_arg.len = dr->argslen<<2;
+	rqstp->rq_prot        = dr->prot;
+	memcpy(&rqstp->rq_addr, &dr->addr, dr->addrlen);
+	rqstp->rq_addrlen     = dr->addrlen;
+	rqstp->rq_daddr       = dr->daddr;
+	rqstp->rq_respages    = rqstp->rq_pages;
+	return dr->argslen<<2;
+}
+
+
+static struct svc_deferred_req *svc_deferred_dequeue(struct svc_xprt *xprt)
+{
+	struct svc_deferred_req *dr = NULL;
+
+	if (!test_bit(XPT_DEFERRED, &xprt->xpt_flags))
+		return NULL;
+	spin_lock(&xprt->xpt_lock);
+	clear_bit(XPT_DEFERRED, &xprt->xpt_flags);
+	if (!list_empty(&xprt->xpt_deferred)) {
+		dr = list_entry(xprt->xpt_deferred.next,
+				struct svc_deferred_req,
+				handle.recent);
+		list_del_init(&dr->handle.recent);
+		set_bit(XPT_DEFERRED, &xprt->xpt_flags);
+	}
+	spin_unlock(&xprt->xpt_lock);
+	return dr;
+}