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 271467c5138d..23165aef59d9 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;
+}