Revert "sunrpc: fix peername failed on closed listener"
[safe/jmp/linux-2.6] / net / sunrpc / svc_xprt.c
index d2ac130..818c4c3 100644 (file)
@@ -5,40 +5,64 @@
  */
 
 #include <linux/sched.h>
+#include <linux/smp_lock.h>
 #include <linux/errno.h>
-#include <linux/fcntl.h>
-#include <linux/net.h>
-#include <linux/in.h>
-#include <linux/inet.h>
-#include <linux/udp.h>
-#include <linux/tcp.h>
-#include <linux/unistd.h>
-#include <linux/slab.h>
-#include <linux/netdevice.h>
-#include <linux/skbuff.h>
-#include <linux/file.h>
 #include <linux/freezer.h>
+#include <linux/kthread.h>
 #include <net/sock.h>
-#include <net/checksum.h>
-#include <net/ip.h>
-#include <net/ipv6.h>
-#include <net/tcp_states.h>
-#include <linux/uaccess.h>
-#include <asm/ioctls.h>
-
-#include <linux/sunrpc/types.h>
-#include <linux/sunrpc/clnt.h>
-#include <linux/sunrpc/xdr.h>
-#include <linux/sunrpc/svcsock.h>
 #include <linux/sunrpc/stats.h>
 #include <linux/sunrpc/svc_xprt.h>
+#include <linux/sunrpc/svcsock.h>
 
 #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;
@@ -70,13 +94,41 @@ void svc_unreg_xprt_class(struct svc_xprt_class *xcl)
 }
 EXPORT_SYMBOL_GPL(svc_unreg_xprt_class);
 
+/*
+ * Format the transport list for printing
+ */
+int svc_print_xprts(char *buf, int maxlen)
+{
+       struct list_head *le;
+       char tmpstr[80];
+       int len = 0;
+       buf[0] = '\0';
+
+       spin_lock(&svc_xprt_class_lock);
+       list_for_each(le, &svc_xprt_class_list) {
+               int slen;
+               struct svc_xprt_class *xcl =
+                       list_entry(le, struct svc_xprt_class, xcl_list);
+
+               sprintf(tmpstr, "%s %d\n", xcl->xcl_name, xcl->xcl_max_payload);
+               slen = strlen(tmpstr);
+               if (len + slen > maxlen)
+                       break;
+               len += slen;
+               strcat(buf, tmpstr);
+       }
+       spin_unlock(&svc_xprt_class_lock);
+
+       return len;
+}
+
 static void svc_xprt_free(struct kref *kref)
 {
        struct svc_xprt *xprt =
                container_of(kref, struct svc_xprt, xpt_ref);
        struct module *owner = xprt->xpt_class->xcl_owner;
-       if (test_bit(XPT_CACHE_AUTH, &xprt->xpt_flags)
-           && xprt->xpt_auth_cache != NULL)
+       if (test_bit(XPT_CACHE_AUTH, &xprt->xpt_flags) &&
+           xprt->xpt_auth_cache != NULL)
                svcauth_unix_info_release(xprt->xpt_auth_cache);
        xprt->xpt_ops->xpo_free(xprt);
        module_put(owner);
@@ -102,44 +154,1078 @@ void svc_xprt_init(struct svc_xprt_class *xcl, struct svc_xprt *xprt,
        xprt->xpt_server = serv;
        INIT_LIST_HEAD(&xprt->xpt_list);
        INIT_LIST_HEAD(&xprt->xpt_ready);
+       INIT_LIST_HEAD(&xprt->xpt_deferred);
        mutex_init(&xprt->xpt_mutex);
        spin_lock_init(&xprt->xpt_lock);
+       set_bit(XPT_BUSY, &xprt->xpt_flags);
+       rpc_init_wait_queue(&xprt->xpt_bc_pending, "xpt_bc_pending");
 }
 EXPORT_SYMBOL_GPL(svc_xprt_init);
 
-int svc_create_xprt(struct svc_serv *serv, char *xprt_name, unsigned short port,
-                   int flags)
+static struct svc_xprt *__svc_xpo_create(struct svc_xprt_class *xcl,
+                                        struct svc_serv *serv,
+                                        const int family,
+                                        const unsigned short port,
+                                        int flags)
 {
-       struct svc_xprt_class *xcl;
-       int ret = -ENOENT;
        struct sockaddr_in sin = {
                .sin_family             = AF_INET,
-               .sin_addr.s_addr        = INADDR_ANY,
+               .sin_addr.s_addr        = htonl(INADDR_ANY),
                .sin_port               = htons(port),
        };
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+       struct sockaddr_in6 sin6 = {
+               .sin6_family            = AF_INET6,
+               .sin6_addr              = IN6ADDR_ANY_INIT,
+               .sin6_port              = htons(port),
+       };
+#endif /* defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) */
+       struct sockaddr *sap;
+       size_t len;
+
+       switch (family) {
+       case PF_INET:
+               sap = (struct sockaddr *)&sin;
+               len = sizeof(sin);
+               break;
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+       case PF_INET6:
+               sap = (struct sockaddr *)&sin6;
+               len = sizeof(sin6);
+               break;
+#endif /* defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) */
+       default:
+               return ERR_PTR(-EAFNOSUPPORT);
+       }
+
+       return xcl->xcl_ops->xpo_create(serv, sap, len, flags);
+}
+
+int svc_create_xprt(struct svc_serv *serv, const char *xprt_name,
+                   const int family, const unsigned short port,
+                   int flags)
+{
+       struct svc_xprt_class *xcl;
+
        dprintk("svc: creating transport %s[%d]\n", xprt_name, port);
        spin_lock(&svc_xprt_class_lock);
        list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list) {
-               if (strcmp(xprt_name, xcl->xcl_name) == 0) {
-                       spin_unlock(&svc_xprt_class_lock);
-                       if (try_module_get(xcl->xcl_owner)) {
-                               struct svc_xprt *newxprt;
-                               ret = 0;
-                               newxprt = xcl->xcl_ops->xpo_create
-                                       (serv,
-                                        (struct sockaddr *)&sin, sizeof(sin),
-                                        flags);
-                               if (IS_ERR(newxprt)) {
-                                       module_put(xcl->xcl_owner);
-                                       ret = PTR_ERR(newxprt);
-                               }
-                       }
-                       goto out;
+               struct svc_xprt *newxprt;
+
+               if (strcmp(xprt_name, xcl->xcl_name))
+                       continue;
+
+               if (!try_module_get(xcl->xcl_owner))
+                       goto err;
+
+               spin_unlock(&svc_xprt_class_lock);
+               newxprt = __svc_xpo_create(xcl, serv, family, port, flags);
+               if (IS_ERR(newxprt)) {
+                       module_put(xcl->xcl_owner);
+                       return PTR_ERR(newxprt);
                }
+
+               clear_bit(XPT_TEMP, &newxprt->xpt_flags);
+               spin_lock_bh(&serv->sv_lock);
+               list_add(&newxprt->xpt_list, &serv->sv_permsocks);
+               spin_unlock_bh(&serv->sv_lock);
+               clear_bit(XPT_BUSY, &newxprt->xpt_flags);
+               return svc_xprt_local_port(newxprt);
        }
+ err:
        spin_unlock(&svc_xprt_class_lock);
        dprintk("svc: transport %s not found\n", xprt_name);
- out:
-       return ret;
+
+       /* This errno is exposed to user space.  Provide a reasonable
+        * perror msg for a bad transport. */
+       return -EPROTONOSUPPORT;
 }
 EXPORT_SYMBOL_GPL(svc_create_xprt);
+
+/*
+ * Copy the local and remote xprt addresses to the rqstp structure
+ */
+void svc_xprt_copy_addrs(struct svc_rqst *rqstp, struct svc_xprt *xprt)
+{
+       struct sockaddr *sin;
+
+       memcpy(&rqstp->rq_addr, &xprt->xpt_remote, xprt->xpt_remotelen);
+       rqstp->rq_addrlen = xprt->xpt_remotelen;
+
+       /*
+        * Destination address in request is needed for binding the
+        * source address in RPC replies/callbacks later.
+        */
+       sin = (struct sockaddr *)&xprt->xpt_local;
+       switch (sin->sa_family) {
+       case AF_INET:
+               rqstp->rq_daddr.addr = ((struct sockaddr_in *)sin)->sin_addr;
+               break;
+       case AF_INET6:
+               rqstp->rq_daddr.addr6 = ((struct sockaddr_in6 *)sin)->sin6_addr;
+               break;
+       }
+}
+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;
+
+       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;
+       }
+
+       pool->sp_stats.packets++;
+
+       /* 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);
+               pool->sp_stats.threads_woken++;
+               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);
+               pool->sp_stats.sockets_queued++;
+               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);
+       }
+}
+EXPORT_SYMBOL_GPL(svc_reserve);
+
+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);
+
+       kfree(rqstp->rq_deferred);
+       rqstp->rq_deferred = NULL;
+
+       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);
+       }
+}
+EXPORT_SYMBOL_GPL(svc_wake_up);
+
+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. It's not clear what will happen if we allow
+ * "too many" connections, but when dealing with network-facing software,
+ * we have to code defensively. Here we do that by imposing hard limits.
+ *
+ * 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.
+ *
+ * single-threaded services that expect a lot of clients will probably
+ * need to set sv_maxconn to override the default value which is based
+ * on the number of threads
+ */
+static void svc_check_conn_limits(struct svc_serv *serv)
+{
+       unsigned int limit = serv->sv_maxconn ? serv->sv_maxconn :
+                               (serv->sv_nrthreads+3) * 20;
+
+       if (serv->sv_tmpcnt > limit) {
+               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 %s\n",
+                                      serv->sv_name, serv->sv_maxconn ?
+                                      "the max number of connections." :
+                                      "the number of threads.");
+                       }
+                       /*
+                        * 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);
+       long                    time_left;
+
+       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) {
+                               set_current_state(TASK_INTERRUPTIBLE);
+                               if (signalled() || kthread_should_stop()) {
+                                       set_current_state(TASK_RUNNING);
+                                       return -EINTR;
+                               }
+                               schedule_timeout(msecs_to_jiffies(500));
+                       }
+                       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() || kthread_should_stop())
+               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);
+
+               /*
+                * checking kthread_should_stop() here allows us to avoid
+                * locking and signalling when stopping kthreads that call
+                * svc_recv. If the thread has already been woken up, then
+                * we can exit here without sleeping. If not, then it
+                * it'll be woken up quickly during the schedule_timeout
+                */
+               if (kthread_should_stop()) {
+                       set_current_state(TASK_RUNNING);
+                       spin_unlock_bh(&pool->sp_lock);
+                       return -EINTR;
+               }
+
+               add_wait_queue(&rqstp->rq_wait, &wait);
+               spin_unlock_bh(&pool->sp_lock);
+
+               time_left = schedule_timeout(timeout);
+
+               try_to_freeze();
+
+               spin_lock_bh(&pool->sp_lock);
+               remove_wait_queue(&rqstp->rq_wait, &wait);
+               if (!time_left)
+                       pool->sp_stats.threads_timedout++;
+
+               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);
+                       if (signalled() || kthread_should_stop())
+                               return -EINTR;
+                       else
+                               return -EAGAIN;
+               }
+       }
+       spin_unlock_bh(&pool->sp_lock);
+
+       len = 0;
+       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 if (!test_bit(XPT_CLOSE, &xprt->xpt_flags)) {
+               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);
+       }
+
+       if (test_bit(XPT_CLOSE, &xprt->xpt_flags)) {
+               dprintk("svc_recv: found XPT_CLOSE\n");
+               svc_delete_xprt(xprt);
+       }
+
+       /* 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;
+}
+EXPORT_SYMBOL_GPL(svc_recv);
+
+/*
+ * Drop request
+ */
+void svc_drop(struct svc_rqst *rqstp)
+{
+       dprintk("svc: xprt %p dropped request\n", rqstp->rq_xprt);
+       svc_xprt_release(rqstp);
+}
+EXPORT_SYMBOL_GPL(svc_drop);
+
+/*
+ * 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);
+       rpc_wake_up(&xprt->xpt_bc_pending);
+       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;
+       struct svc_deferred_req *dr;
+
+       /* Only do this once */
+       if (test_and_set_bit(XPT_DEAD, &xprt->xpt_flags))
+               return;
+
+       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_bit(XPT_TEMP, &xprt->xpt_flags))
+               serv->sv_tmpcnt--;
+
+       while ((dr = svc_deferred_dequeue(xprt)) != NULL)
+               kfree(dr);
+
+       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);
+}
+EXPORT_SYMBOL_GPL(svc_close_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;
+
+       spin_lock(&xprt->xpt_lock);
+       set_bit(XPT_DEFERRED, &xprt->xpt_flags);
+       if (too_many || test_bit(XPT_DEAD, &xprt->xpt_flags)) {
+               spin_unlock(&xprt->xpt_lock);
+               dprintk("revisit canceled\n");
+               svc_xprt_put(xprt);
+               kfree(dr);
+               return;
+       }
+       dprintk("revisit queued\n");
+       dr->xprt = NULL;
+       list_add(&dr->handle.recent, &xprt->xpt_deferred);
+       spin_unlock(&xprt->xpt_lock);
+       svc_xprt_enqueue(xprt);
+       svc_xprt_put(xprt);
+}
+
+/*
+ * Save the request off for later processing. The request buffer looks
+ * like this:
+ *
+ * <xprt-header><rpc-header><rpc-pagelist><rpc-tail>
+ *
+ * This code can only handle requests that consist of an xprt-header
+ * and rpc-header.
+ */
+static struct cache_deferred_req *svc_defer(struct cache_req *req)
+{
+       struct svc_rqst *rqstp = container_of(req, struct svc_rqst, rq_chandle);
+       struct svc_deferred_req *dr;
+
+       if (rqstp->rq_arg.page_len || !rqstp->rq_usedeferral)
+               return NULL; /* if more than a page, give up FIXME */
+       if (rqstp->rq_deferred) {
+               dr = rqstp->rq_deferred;
+               rqstp->rq_deferred = NULL;
+       } else {
+               size_t skip;
+               size_t size;
+               /* FIXME maybe discard if size too large */
+               size = sizeof(struct svc_deferred_req) + rqstp->rq_arg.len;
+               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;
+               dr->xprt_hlen = rqstp->rq_xprt_hlen;
+
+               /* back up head to the start of the buffer and copy */
+               skip = rqstp->rq_arg.len - rqstp->rq_arg.head[0].iov_len;
+               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;
+
+       /* setup iov_base past transport header */
+       rqstp->rq_arg.head[0].iov_base = dr->args + (dr->xprt_hlen>>2);
+       /* The iov_len does not include the transport header bytes */
+       rqstp->rq_arg.head[0].iov_len = (dr->argslen<<2) - dr->xprt_hlen;
+       rqstp->rq_arg.page_len = 0;
+       /* The rq_arg.len includes the transport header bytes */
+       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;
+       /* Save off transport header len in case we get deferred again */
+       rqstp->rq_xprt_hlen   = dr->xprt_hlen;
+       rqstp->rq_daddr       = dr->daddr;
+       rqstp->rq_respages    = rqstp->rq_pages;
+       return (dr->argslen<<2) - dr->xprt_hlen;
+}
+
+
+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;
+}
+
+/**
+ * svc_find_xprt - find an RPC transport instance
+ * @serv: pointer to svc_serv to search
+ * @xcl_name: C string containing transport's class name
+ * @af: Address family of transport's local address
+ * @port: transport's IP port number
+ *
+ * Return the transport instance pointer for the endpoint accepting
+ * connections/peer traffic from the specified transport class,
+ * address family and port.
+ *
+ * Specifying 0 for the address family or port is effectively a
+ * wild-card, and will result in matching the first transport in the
+ * service's list that has a matching class name.
+ */
+struct svc_xprt *svc_find_xprt(struct svc_serv *serv, const char *xcl_name,
+                              const sa_family_t af, const unsigned short port)
+{
+       struct svc_xprt *xprt;
+       struct svc_xprt *found = NULL;
+
+       /* Sanity check the args */
+       if (serv == NULL || xcl_name == NULL)
+               return found;
+
+       spin_lock_bh(&serv->sv_lock);
+       list_for_each_entry(xprt, &serv->sv_permsocks, xpt_list) {
+               if (strcmp(xprt->xpt_class->xcl_name, xcl_name))
+                       continue;
+               if (af != AF_UNSPEC && af != xprt->xpt_local.ss_family)
+                       continue;
+               if (port != 0 && port != svc_xprt_local_port(xprt))
+                       continue;
+               found = xprt;
+               svc_xprt_get(xprt);
+               break;
+       }
+       spin_unlock_bh(&serv->sv_lock);
+       return found;
+}
+EXPORT_SYMBOL_GPL(svc_find_xprt);
+
+static int svc_one_xprt_name(const struct svc_xprt *xprt,
+                            char *pos, int remaining)
+{
+       int len;
+
+       len = snprintf(pos, remaining, "%s %u\n",
+                       xprt->xpt_class->xcl_name,
+                       svc_xprt_local_port(xprt));
+       if (len >= remaining)
+               return -ENAMETOOLONG;
+       return len;
+}
+
+/**
+ * svc_xprt_names - format a buffer with a list of transport names
+ * @serv: pointer to an RPC service
+ * @buf: pointer to a buffer to be filled in
+ * @buflen: length of buffer to be filled in
+ *
+ * Fills in @buf with a string containing a list of transport names,
+ * each name terminated with '\n'.
+ *
+ * Returns positive length of the filled-in string on success; otherwise
+ * a negative errno value is returned if an error occurs.
+ */
+int svc_xprt_names(struct svc_serv *serv, char *buf, const int buflen)
+{
+       struct svc_xprt *xprt;
+       int len, totlen;
+       char *pos;
+
+       /* Sanity check args */
+       if (!serv)
+               return 0;
+
+       spin_lock_bh(&serv->sv_lock);
+
+       pos = buf;
+       totlen = 0;
+       list_for_each_entry(xprt, &serv->sv_permsocks, xpt_list) {
+               len = svc_one_xprt_name(xprt, pos, buflen - totlen);
+               if (len < 0) {
+                       *buf = '\0';
+                       totlen = len;
+               }
+               if (len <= 0)
+                       break;
+
+               pos += len;
+               totlen += len;
+       }
+
+       spin_unlock_bh(&serv->sv_lock);
+       return totlen;
+}
+EXPORT_SYMBOL_GPL(svc_xprt_names);
+
+
+/*----------------------------------------------------------------------------*/
+
+static void *svc_pool_stats_start(struct seq_file *m, loff_t *pos)
+{
+       unsigned int pidx = (unsigned int)*pos;
+       struct svc_serv *serv = m->private;
+
+       dprintk("svc_pool_stats_start, *pidx=%u\n", pidx);
+
+       if (!pidx)
+               return SEQ_START_TOKEN;
+       return (pidx > serv->sv_nrpools ? NULL : &serv->sv_pools[pidx-1]);
+}
+
+static void *svc_pool_stats_next(struct seq_file *m, void *p, loff_t *pos)
+{
+       struct svc_pool *pool = p;
+       struct svc_serv *serv = m->private;
+
+       dprintk("svc_pool_stats_next, *pos=%llu\n", *pos);
+
+       if (p == SEQ_START_TOKEN) {
+               pool = &serv->sv_pools[0];
+       } else {
+               unsigned int pidx = (pool - &serv->sv_pools[0]);
+               if (pidx < serv->sv_nrpools-1)
+                       pool = &serv->sv_pools[pidx+1];
+               else
+                       pool = NULL;
+       }
+       ++*pos;
+       return pool;
+}
+
+static void svc_pool_stats_stop(struct seq_file *m, void *p)
+{
+}
+
+static int svc_pool_stats_show(struct seq_file *m, void *p)
+{
+       struct svc_pool *pool = p;
+
+       if (p == SEQ_START_TOKEN) {
+               seq_puts(m, "# pool packets-arrived sockets-enqueued threads-woken threads-timedout\n");
+               return 0;
+       }
+
+       seq_printf(m, "%u %lu %lu %lu %lu\n",
+               pool->sp_id,
+               pool->sp_stats.packets,
+               pool->sp_stats.sockets_queued,
+               pool->sp_stats.threads_woken,
+               pool->sp_stats.threads_timedout);
+
+       return 0;
+}
+
+static const struct seq_operations svc_pool_stats_seq_ops = {
+       .start  = svc_pool_stats_start,
+       .next   = svc_pool_stats_next,
+       .stop   = svc_pool_stats_stop,
+       .show   = svc_pool_stats_show,
+};
+
+int svc_pool_stats_open(struct svc_serv *serv, struct file *file)
+{
+       int err;
+
+       err = seq_open(file, &svc_pool_stats_seq_ops);
+       if (!err)
+               ((struct seq_file *) file->private_data)->private = serv;
+       return err;
+}
+EXPORT_SYMBOL(svc_pool_stats_open);
+
+/*----------------------------------------------------------------------------*/