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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * linux/net/sunrpc/xprtsock.c
  *
  * Client-side transport implementation for sockets.
  *
  * TCP callback races fixes (C) 1998 Red Hat
  * TCP send fixes (C) 1998 Red Hat
  * TCP NFS related read + write fixes
  *  (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
  *
  * Rewrite of larges part of the code in order to stabilize TCP stuff.
  * Fix behaviour when socket buffer is full.
  *  (C) 1999 Trond Myklebust <trond.myklebust@fys.uio.no>
  *
  * IP socket transport implementation, (C) 2005 Chuck Lever <cel@netapp.com>
  *
  * IPv6 support contributed by Gilles Quillard, Bull Open Source, 2005.
  *   <gilles.quillard@bull.net>
  */
 
 #include <linux/types.h>
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/capability.h>
 #include <linux/pagemap.h>
 #include <linux/errno.h>
 #include <linux/socket.h>
 #include <linux/in.h>
 #include <linux/net.h>
 #include <linux/mm.h>
 #include <linux/un.h>
 #include <linux/udp.h>
 #include <linux/tcp.h>
 #include <linux/sunrpc/clnt.h>
 #include <linux/sunrpc/addr.h>
 #include <linux/sunrpc/sched.h>
 #include <linux/sunrpc/svcsock.h>
 #include <linux/sunrpc/xprtsock.h>
 #include <linux/file.h>
 #ifdef CONFIG_SUNRPC_BACKCHANNEL
 #include <linux/sunrpc/bc_xprt.h>
 #endif
 
 #include <net/sock.h>
 #include <net/checksum.h>
 #include <net/udp.h>
 #include <net/tcp.h>
 #include <linux/bvec.h>
 #include <linux/highmem.h>
 #include <linux/uio.h>
 #include <linux/sched/mm.h>
 
 #include <trace/events/sunrpc.h>
 
 #include "socklib.h"
 #include "sunrpc.h"
 
 static void xs_close(struct rpc_xprt *xprt);
 static void xs_set_srcport(struct sock_xprt *transport, struct socket *sock);
 static void xs_tcp_set_socket_timeouts(struct rpc_xprt *xprt,
         struct socket *sock);
 
 /*
  * xprtsock tunables
  */
 static unsigned int xprt_udp_slot_table_entries = RPC_DEF_SLOT_TABLE;
 static unsigned int xprt_tcp_slot_table_entries = RPC_MIN_SLOT_TABLE;
 static unsigned int xprt_max_tcp_slot_table_entries = RPC_MAX_SLOT_TABLE;
 
 static unsigned int xprt_min_resvport = RPC_DEF_MIN_RESVPORT;
 static unsigned int xprt_max_resvport = RPC_DEF_MAX_RESVPORT;
 
 #define XS_TCP_LINGER_TO    (15U * HZ)
 static unsigned int xs_tcp_fin_timeout __read_mostly = XS_TCP_LINGER_TO;
 
 /*
  * We can register our own files under /proc/sys/sunrpc by
  * calling register_sysctl_table() again.  The files in that
  * directory become the union of all files registered there.
  *
  * We simply need to make sure that we don't collide with
  * someone else's file names!
  */
 
 static unsigned int min_slot_table_size = RPC_MIN_SLOT_TABLE;
 static unsigned int max_slot_table_size = RPC_MAX_SLOT_TABLE;
 static unsigned int max_tcp_slot_table_limit = RPC_MAX_SLOT_TABLE_LIMIT;
 static unsigned int xprt_min_resvport_limit = RPC_MIN_RESVPORT;
 static unsigned int xprt_max_resvport_limit = RPC_MAX_RESVPORT;
 
 static struct ctl_table_header *sunrpc_table_header;
 
 static struct xprt_class xs_local_transport;
 static struct xprt_class xs_udp_transport;
 static struct xprt_class xs_tcp_transport;
 static struct xprt_class xs_bc_tcp_transport;
 
 /*
  * FIXME: changing the UDP slot table size should also resize the UDP
  *        socket buffers for existing UDP transports
  */
 static struct ctl_table xs_tunables_table[] = {
     {
         .procname   = "udp_slot_table_entries",
         .data       = &xprt_udp_slot_table_entries,
         .maxlen     = sizeof(unsigned int),
         .mode       = 0644,
         .proc_handler   = proc_dointvec_minmax,
         .extra1     = &min_slot_table_size,
         .extra2     = &max_slot_table_size
     },
     {
         .procname   = "tcp_slot_table_entries",
         .data       = &xprt_tcp_slot_table_entries,
         .maxlen     = sizeof(unsigned int),
         .mode       = 0644,
         .proc_handler   = proc_dointvec_minmax,
         .extra1     = &min_slot_table_size,
         .extra2     = &max_slot_table_size
     },
     {
         .procname   = "tcp_max_slot_table_entries",
         .data       = &xprt_max_tcp_slot_table_entries,
         .maxlen     = sizeof(unsigned int),
         .mode       = 0644,
         .proc_handler   = proc_dointvec_minmax,
         .extra1     = &min_slot_table_size,
         .extra2     = &max_tcp_slot_table_limit
     },
     {
         .procname   = "min_resvport",
         .data       = &xprt_min_resvport,
         .maxlen     = sizeof(unsigned int),
         .mode       = 0644,
         .proc_handler   = proc_dointvec_minmax,
         .extra1     = &xprt_min_resvport_limit,
         .extra2     = &xprt_max_resvport_limit
     },
     {
         .procname   = "max_resvport",
         .data       = &xprt_max_resvport,
         .maxlen     = sizeof(unsigned int),
         .mode       = 0644,
         .proc_handler   = proc_dointvec_minmax,
         .extra1     = &xprt_min_resvport_limit,
         .extra2     = &xprt_max_resvport_limit
     },
     {
         .procname   = "tcp_fin_timeout",
         .data       = &xs_tcp_fin_timeout,
         .maxlen     = sizeof(xs_tcp_fin_timeout),
         .mode       = 0644,
         .proc_handler   = proc_dointvec_jiffies,
     },
     { },
 };
 
 static struct ctl_table sunrpc_table[] = {
     {
         .procname   = "sunrpc",
         .mode       = 0555,
         .child      = xs_tunables_table
     },
     { },
 };
 
 /*
  * Wait duration for a reply from the RPC portmapper.
  */
 #define XS_BIND_TO      (60U * HZ)
 
 /*
  * Delay if a UDP socket connect error occurs.  This is most likely some
  * kind of resource problem on the local host.
  */
 #define XS_UDP_REEST_TO     (2U * HZ)
 
 /*
  * The reestablish timeout allows clients to delay for a bit before attempting
  * to reconnect to a server that just dropped our connection.
  *
  * We implement an exponential backoff when trying to reestablish a TCP
  * transport connection with the server.  Some servers like to drop a TCP
  * connection when they are overworked, so we start with a short timeout and
  * increase over time if the server is down or not responding.
  */
 #define XS_TCP_INIT_REEST_TO    (3U * HZ)
 
 /*
  * TCP idle timeout; client drops the transport socket if it is idle
  * for this long.  Note that we also timeout UDP sockets to prevent
  * holding port numbers when there is no RPC traffic.
  */
 #define XS_IDLE_DISC_TO     (5U * 60 * HZ)
 
 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 # undef  RPC_DEBUG_DATA
 # define RPCDBG_FACILITY    RPCDBG_TRANS
 #endif
 
 #ifdef RPC_DEBUG_DATA
 static void xs_pktdump(char *msg, u32 *packet, unsigned int count)
 {
     u8 *buf = (u8 *) packet;
     int j;
 
     dprintk("RPC:       %s\n", msg);
     for (j = 0; j < count && j < 128; j += 4) {
         if (!(j & 31)) {
             if (j)
                 dprintk("\n");
             dprintk("0x%04x ", j);
         }
         dprintk("%02x%02x%02x%02x ",
             buf[j], buf[j+1], buf[j+2], buf[j+3]);
     }
     dprintk("\n");
 }
 #else
 static inline void xs_pktdump(char *msg, u32 *packet, unsigned int count)
 {
     /* NOP */
 }
 #endif
 
 static inline struct rpc_xprt *xprt_from_sock(struct sock *sk)
 {
     return (struct rpc_xprt *) sk->sk_user_data;
 }
 
 static inline struct sockaddr *xs_addr(struct rpc_xprt *xprt)
 {
     return (struct sockaddr *) &xprt->addr;
 }
 
 static inline struct sockaddr_un *xs_addr_un(struct rpc_xprt *xprt)
 {
     return (struct sockaddr_un *) &xprt->addr;
 }
 
 static inline struct sockaddr_in *xs_addr_in(struct rpc_xprt *xprt)
 {
     return (struct sockaddr_in *) &xprt->addr;
 }
 
 static inline struct sockaddr_in6 *xs_addr_in6(struct rpc_xprt *xprt)
 {
     return (struct sockaddr_in6 *) &xprt->addr;
 }
 
 static void xs_format_common_peer_addresses(struct rpc_xprt *xprt)
 {
     struct sockaddr *sap = xs_addr(xprt);
     struct sockaddr_in6 *sin6;
     struct sockaddr_in *sin;
     struct sockaddr_un *sun;
     char buf[128];
 
     switch (sap->sa_family) {
     case AF_LOCAL:
         sun = xs_addr_un(xprt);
         strlcpy(buf, sun->sun_path, sizeof(buf));
         xprt->address_strings[RPC_DISPLAY_ADDR] =
                         kstrdup(buf, GFP_KERNEL);
         break;
     case AF_INET:
         (void)rpc_ntop(sap, buf, sizeof(buf));
         xprt->address_strings[RPC_DISPLAY_ADDR] =
                         kstrdup(buf, GFP_KERNEL);
         sin = xs_addr_in(xprt);
         snprintf(buf, sizeof(buf), "%08x", ntohl(sin->sin_addr.s_addr));
         break;
     case AF_INET6:
         (void)rpc_ntop(sap, buf, sizeof(buf));
         xprt->address_strings[RPC_DISPLAY_ADDR] =
                         kstrdup(buf, GFP_KERNEL);
         sin6 = xs_addr_in6(xprt);
         snprintf(buf, sizeof(buf), "%pi6", &sin6->sin6_addr);
         break;
     default:
         BUG();
     }
 
     xprt->address_strings[RPC_DISPLAY_HEX_ADDR] = kstrdup(buf, GFP_KERNEL);
 }
 
 static void xs_format_common_peer_ports(struct rpc_xprt *xprt)
 {
     struct sockaddr *sap = xs_addr(xprt);
     char buf[128];
 
     snprintf(buf, sizeof(buf), "%u", rpc_get_port(sap));
     xprt->address_strings[RPC_DISPLAY_PORT] = kstrdup(buf, GFP_KERNEL);
 
     snprintf(buf, sizeof(buf), "%4hx", rpc_get_port(sap));
     xprt->address_strings[RPC_DISPLAY_HEX_PORT] = kstrdup(buf, GFP_KERNEL);
 }
 
 static void xs_format_peer_addresses(struct rpc_xprt *xprt,
                      const char *protocol,
                      const char *netid)
 {
     xprt->address_strings[RPC_DISPLAY_PROTO] = protocol;
     xprt->address_strings[RPC_DISPLAY_NETID] = netid;
     xs_format_common_peer_addresses(xprt);
     xs_format_common_peer_ports(xprt);
 }
 
 static void xs_update_peer_port(struct rpc_xprt *xprt)
 {
     kfree(xprt->address_strings[RPC_DISPLAY_HEX_PORT]);
     kfree(xprt->address_strings[RPC_DISPLAY_PORT]);
 
     xs_format_common_peer_ports(xprt);
 }
 
 static void xs_free_peer_addresses(struct rpc_xprt *xprt)
 {
     unsigned int i;
 
     for (i = 0; i < RPC_DISPLAY_MAX; i++)
         switch (i) {
         case RPC_DISPLAY_PROTO:
         case RPC_DISPLAY_NETID:
             continue;
         default:
             kfree(xprt->address_strings[i]);
         }
 }
 
 static size_t
 xs_alloc_sparse_pages(struct xdr_buf *buf, size_t want, gfp_t gfp)
 {
     size_t i,n;
 
     if (!want || !(buf->flags & XDRBUF_SPARSE_PAGES))
         return want;
     n = (buf->page_base + want + PAGE_SIZE - 1) >> PAGE_SHIFT;
     for (i = 0; i < n; i++) {
         if (buf->pages[i])
             continue;
         buf->bvec[i].bv_page = buf->pages[i] = alloc_page(gfp);
         if (!buf->pages[i]) {
             i *= PAGE_SIZE;
             return i > buf->page_base ? i - buf->page_base : 0;
         }
     }
     return want;
 }
 
 static ssize_t
 xs_sock_recvmsg(struct socket *sock, struct msghdr *msg, int flags, size_t seek)
 {
     ssize_t ret;
     if (seek != 0)
         iov_iter_advance(&msg->msg_iter, seek);
     ret = sock_recvmsg(sock, msg, flags);
     return ret > 0 ? ret + seek : ret;
 }
 
 static ssize_t
 xs_read_kvec(struct socket *sock, struct msghdr *msg, int flags,
         struct kvec *kvec, size_t count, size_t seek)
 {
     iov_iter_kvec(&msg->msg_iter, READ, kvec, 1, count);
     return xs_sock_recvmsg(sock, msg, flags, seek);
 }
 
 static ssize_t
 xs_read_bvec(struct socket *sock, struct msghdr *msg, int flags,
         struct bio_vec *bvec, unsigned long nr, size_t count,
         size_t seek)
 {
     iov_iter_bvec(&msg->msg_iter, READ, bvec, nr, count);
     return xs_sock_recvmsg(sock, msg, flags, seek);
 }
 
 static ssize_t
 xs_read_discard(struct socket *sock, struct msghdr *msg, int flags,
         size_t count)
 {
     iov_iter_discard(&msg->msg_iter, READ, count);
     return sock_recvmsg(sock, msg, flags);
 }
 
 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 static void
 xs_flush_bvec(const struct bio_vec *bvec, size_t count, size_t seek)
 {
     struct bvec_iter bi = {
         .bi_size = count,
     };
     struct bio_vec bv;
 
     bvec_iter_advance(bvec, &bi, seek & PAGE_MASK);
     for_each_bvec(bv, bvec, bi, bi)
         flush_dcache_page(bv.bv_page);
 }
 #else
 static inline void
 xs_flush_bvec(const struct bio_vec *bvec, size_t count, size_t seek)
 {
 }
 #endif
 
 static ssize_t
 xs_read_xdr_buf(struct socket *sock, struct msghdr *msg, int flags,
         struct xdr_buf *buf, size_t count, size_t seek, size_t *read)
 {
     size_t want, seek_init = seek, offset = 0;
     ssize_t ret;
 
     want = min_t(size_t, count, buf->head[0].iov_len);
     if (seek < want) {
         ret = xs_read_kvec(sock, msg, flags, &buf->head[0], want, seek);
         if (ret <= 0)
             goto sock_err;
         offset += ret;
         if (offset == count || msg->msg_flags & (MSG_EOR|MSG_TRUNC))
             goto out;
         if (ret != want)
             goto out;
         seek = 0;
     } else {
         seek -= want;
         offset += want;
     }
 
     want = xs_alloc_sparse_pages(
         buf, min_t(size_t, count - offset, buf->page_len),
         GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
     if (seek < want) {
         ret = xs_read_bvec(sock, msg, flags, buf->bvec,
                 xdr_buf_pagecount(buf),
                 want + buf->page_base,
                 seek + buf->page_base);
         if (ret <= 0)
             goto sock_err;
         xs_flush_bvec(buf->bvec, ret, seek + buf->page_base);
         ret -= buf->page_base;
         offset += ret;
         if (offset == count || msg->msg_flags & (MSG_EOR|MSG_TRUNC))
             goto out;
         if (ret != want)
             goto out;
         seek = 0;
     } else {
         seek -= want;
         offset += want;
     }
 
     want = min_t(size_t, count - offset, buf->tail[0].iov_len);
     if (seek < want) {
         ret = xs_read_kvec(sock, msg, flags, &buf->tail[0], want, seek);
         if (ret <= 0)
             goto sock_err;
         offset += ret;
         if (offset == count || msg->msg_flags & (MSG_EOR|MSG_TRUNC))
             goto out;
         if (ret != want)
             goto out;
     } else if (offset < seek_init)
         offset = seek_init;
     ret = -EMSGSIZE;
 out:
     *read = offset - seek_init;
     return ret;
 sock_err:
     offset += seek;
     goto out;
 }
 
 static void
 xs_read_header(struct sock_xprt *transport, struct xdr_buf *buf)
 {
     if (!transport->recv.copied) {
         if (buf->head[0].iov_len >= transport->recv.offset)
             memcpy(buf->head[0].iov_base,
                     &transport->recv.xid,
                     transport->recv.offset);
         transport->recv.copied = transport->recv.offset;
     }
 }
 
 static bool
 xs_read_stream_request_done(struct sock_xprt *transport)
 {
     return transport->recv.fraghdr & cpu_to_be32(RPC_LAST_STREAM_FRAGMENT);
 }
 
 static void
 xs_read_stream_check_eor(struct sock_xprt *transport,
         struct msghdr *msg)
 {
     if (xs_read_stream_request_done(transport))
         msg->msg_flags |= MSG_EOR;
 }
 
 static ssize_t
 xs_read_stream_request(struct sock_xprt *transport, struct msghdr *msg,
         int flags, struct rpc_rqst *req)
 {
     struct xdr_buf *buf = &req->rq_private_buf;
     size_t want, read;
     ssize_t ret;
 
     xs_read_header(transport, buf);
 
     want = transport->recv.len - transport->recv.offset;
     if (want != 0) {
         ret = xs_read_xdr_buf(transport->sock, msg, flags, buf,
                 transport->recv.copied + want,
                 transport->recv.copied,
                 &read);
         transport->recv.offset += read;
         transport->recv.copied += read;
     }
 
     if (transport->recv.offset == transport->recv.len)
         xs_read_stream_check_eor(transport, msg);
 
     if (want == 0)
         return 0;
 
     switch (ret) {
     default:
         break;
     case -EFAULT:
     case -EMSGSIZE:
         msg->msg_flags |= MSG_TRUNC;
         return read;
     case 0:
         return -ESHUTDOWN;
     }
     return ret < 0 ? ret : read;
 }
 
 static size_t
 xs_read_stream_headersize(bool isfrag)
 {
     if (isfrag)
         return sizeof(__be32);
     return 3 * sizeof(__be32);
 }
 
 static ssize_t
 xs_read_stream_header(struct sock_xprt *transport, struct msghdr *msg,
         int flags, size_t want, size_t seek)
 {
     struct kvec kvec = {
         .iov_base = &transport->recv.fraghdr,
         .iov_len = want,
     };
     return xs_read_kvec(transport->sock, msg, flags, &kvec, want, seek);
 }
 
 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
 static ssize_t
 xs_read_stream_call(struct sock_xprt *transport, struct msghdr *msg, int flags)
 {
     struct rpc_xprt *xprt = &transport->xprt;
     struct rpc_rqst *req;
     ssize_t ret;
 
     /* Is this transport associated with the backchannel? */
     if (!xprt->bc_serv)
         return -ESHUTDOWN;
 
     /* Look up and lock the request corresponding to the given XID */
     req = xprt_lookup_bc_request(xprt, transport->recv.xid);
     if (!req) {
         printk(KERN_WARNING "Callback slot table overflowed\n");
         return -ESHUTDOWN;
     }
     if (transport->recv.copied && !req->rq_private_buf.len)
         return -ESHUTDOWN;
 
     ret = xs_read_stream_request(transport, msg, flags, req);
     if (msg->msg_flags & (MSG_EOR|MSG_TRUNC))
         xprt_complete_bc_request(req, transport->recv.copied);
     else
         req->rq_private_buf.len = transport->recv.copied;
 
     return ret;
 }
 #else /* CONFIG_SUNRPC_BACKCHANNEL */
 static ssize_t
 xs_read_stream_call(struct sock_xprt *transport, struct msghdr *msg, int flags)
 {
     return -ESHUTDOWN;
 }
 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
 
 static ssize_t
 xs_read_stream_reply(struct sock_xprt *transport, struct msghdr *msg, int flags)
 {
     struct rpc_xprt *xprt = &transport->xprt;
     struct rpc_rqst *req;
     ssize_t ret = 0;
 
     /* Look up and lock the request corresponding to the given XID */
     spin_lock(&xprt->queue_lock);
     req = xprt_lookup_rqst(xprt, transport->recv.xid);
     if (!req || (transport->recv.copied && !req->rq_private_buf.len)) {
         msg->msg_flags |= MSG_TRUNC;
         goto out;
     }
     xprt_pin_rqst(req);
     spin_unlock(&xprt->queue_lock);
 
     ret = xs_read_stream_request(transport, msg, flags, req);
 
     spin_lock(&xprt->queue_lock);
     if (msg->msg_flags & (MSG_EOR|MSG_TRUNC))
         xprt_complete_rqst(req->rq_task, transport->recv.copied);
     else
         req->rq_private_buf.len = transport->recv.copied;
     xprt_unpin_rqst(req);
 out:
     spin_unlock(&xprt->queue_lock);
     return ret;
 }
 
 static ssize_t
 xs_read_stream(struct sock_xprt *transport, int flags)
 {
     struct msghdr msg = { 0 };
     size_t want, read = 0;
     ssize_t ret = 0;
 
     if (transport->recv.len == 0) {
         want = xs_read_stream_headersize(transport->recv.copied != 0);
         ret = xs_read_stream_header(transport, &msg, flags, want,
                 transport->recv.offset);
         if (ret <= 0)
             goto out_err;
         transport->recv.offset = ret;
         if (transport->recv.offset != want)
             return transport->recv.offset;
         transport->recv.len = be32_to_cpu(transport->recv.fraghdr) &
             RPC_FRAGMENT_SIZE_MASK;
         transport->recv.offset -= sizeof(transport->recv.fraghdr);
         read = ret;
     }
 
     switch (be32_to_cpu(transport->recv.calldir)) {
     default:
         msg.msg_flags |= MSG_TRUNC;
         break;
     case RPC_CALL:
         ret = xs_read_stream_call(transport, &msg, flags);
         break;
     case RPC_REPLY:
         ret = xs_read_stream_reply(transport, &msg, flags);
     }
     if (msg.msg_flags & MSG_TRUNC) {
         transport->recv.calldir = cpu_to_be32(-1);
         transport->recv.copied = -1;
     }
     if (ret < 0)
         goto out_err;
     read += ret;
     if (transport->recv.offset < transport->recv.len) {
         if (!(msg.msg_flags & MSG_TRUNC))
             return read;
         msg.msg_flags = 0;
         ret = xs_read_discard(transport->sock, &msg, flags,
                 transport->recv.len - transport->recv.offset);
         if (ret <= 0)
             goto out_err;
         transport->recv.offset += ret;
         read += ret;
         if (transport->recv.offset != transport->recv.len)
             return read;
     }
     if (xs_read_stream_request_done(transport)) {
         trace_xs_stream_read_request(transport);
         transport->recv.copied = 0;
     }
     transport->recv.offset = 0;
     transport->recv.len = 0;
     return read;
 out_err:
     return ret != 0 ? ret : -ESHUTDOWN;
 }
 
 static __poll_t xs_poll_socket(struct sock_xprt *transport)
 {
     return transport->sock->ops->poll(transport->file, transport->sock,
             NULL);
 }
 
 static bool xs_poll_socket_readable(struct sock_xprt *transport)
 {
     __poll_t events = xs_poll_socket(transport);
 
     return (events & (EPOLLIN | EPOLLRDNORM)) && !(events & EPOLLRDHUP);
 }
 
 static void xs_poll_check_readable(struct sock_xprt *transport)
 {
 
     clear_bit(XPRT_SOCK_DATA_READY, &transport->sock_state);
     if (!xs_poll_socket_readable(transport))
         return;
     if (!test_and_set_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))
         queue_work(xprtiod_workqueue, &transport->recv_worker);
 }
 
 static void xs_stream_data_receive(struct sock_xprt *transport)
 {
     size_t read = 0;
     ssize_t ret = 0;
 
     mutex_lock(&transport->recv_mutex);
     if (transport->sock == NULL)
         goto out;
     for (;;) {
         ret = xs_read_stream(transport, MSG_DONTWAIT);
         if (ret < 0)
             break;
         read += ret;
         cond_resched();
     }
     if (ret == -ESHUTDOWN)
         kernel_sock_shutdown(transport->sock, SHUT_RDWR);
     else
         xs_poll_check_readable(transport);
 out:
     mutex_unlock(&transport->recv_mutex);
     trace_xs_stream_read_data(&transport->xprt, ret, read);
 }
 
 static void xs_stream_data_receive_workfn(struct work_struct *work)
 {
     struct sock_xprt *transport =
         container_of(work, struct sock_xprt, recv_worker);
     unsigned int pflags = memalloc_nofs_save();
 
     xs_stream_data_receive(transport);
     memalloc_nofs_restore(pflags);
 }
 
 static void
 xs_stream_reset_connect(struct sock_xprt *transport)
 {
     transport->recv.offset = 0;
     transport->recv.len = 0;
     transport->recv.copied = 0;
     transport->xmit.offset = 0;
 }
 
 static void
 xs_stream_start_connect(struct sock_xprt *transport)
 {
     transport->xprt.stat.connect_count++;
     transport->xprt.stat.connect_start = jiffies;
 }
 
 #define XS_SENDMSG_FLAGS    (MSG_DONTWAIT | MSG_NOSIGNAL)
 
 /**
  * xs_nospace - handle transmit was incomplete
  * @req: pointer to RPC request
  * @transport: pointer to struct sock_xprt
  *
  */
 static int xs_nospace(struct rpc_rqst *req, struct sock_xprt *transport)
 {
     struct rpc_xprt *xprt = &transport->xprt;
     struct sock *sk = transport->inet;
     int ret = -EAGAIN;
 
     trace_rpc_socket_nospace(req, transport);
 
     /* Protect against races with write_space */
     spin_lock(&xprt->transport_lock);
 
     /* Don't race with disconnect */
     if (xprt_connected(xprt)) {
         /* wait for more buffer space */
         set_bit(XPRT_SOCK_NOSPACE, &transport->sock_state);
         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
         sk->sk_write_pending++;
         xprt_wait_for_buffer_space(xprt);
     } else
         ret = -ENOTCONN;
 
     spin_unlock(&xprt->transport_lock);
     return ret;
 }
 
 static int xs_sock_nospace(struct rpc_rqst *req)
 {
     struct sock_xprt *transport =
         container_of(req->rq_xprt, struct sock_xprt, xprt);
     struct sock *sk = transport->inet;
     int ret = -EAGAIN;
 
     lock_sock(sk);
     if (!sock_writeable(sk))
         ret = xs_nospace(req, transport);
     release_sock(sk);
     return ret;
 }
 
 static int xs_stream_nospace(struct rpc_rqst *req, bool vm_wait)
 {
     struct sock_xprt *transport =
         container_of(req->rq_xprt, struct sock_xprt, xprt);
     struct sock *sk = transport->inet;
     int ret = -EAGAIN;
 
     if (vm_wait)
         return -ENOBUFS;
     lock_sock(sk);
     if (!sk_stream_memory_free(sk))
         ret = xs_nospace(req, transport);
     release_sock(sk);
     return ret;
 }
 
 static int xs_stream_prepare_request(struct rpc_rqst *req, struct xdr_buf *buf)
 {
     return xdr_alloc_bvec(buf, rpc_task_gfp_mask());
 }
 
 /*
  * Determine if the previous message in the stream was aborted before it
  * could complete transmission.
  */
 static bool
 xs_send_request_was_aborted(struct sock_xprt *transport, struct rpc_rqst *req)
 {
     return transport->xmit.offset != 0 && req->rq_bytes_sent == 0;
 }
 
 /*
  * Return the stream record marker field for a record of length < 2^31-1
  */
 static rpc_fraghdr
 xs_stream_record_marker(struct xdr_buf *xdr)
 {
     if (!xdr->len)
         return 0;
     return cpu_to_be32(RPC_LAST_STREAM_FRAGMENT | (u32)xdr->len);
 }
 
 /**
  * xs_local_send_request - write an RPC request to an AF_LOCAL socket
  * @req: pointer to RPC request
  *
  * Return values:
  *        0:    The request has been sent
  *   EAGAIN:    The socket was blocked, please call again later to
  *      complete the request
  * ENOTCONN:    Caller needs to invoke connect logic then call again
  *    other:    Some other error occurred, the request was not sent
  */
 static int xs_local_send_request(struct rpc_rqst *req)
 {
     struct rpc_xprt *xprt = req->rq_xprt;
     struct sock_xprt *transport =
                 container_of(xprt, struct sock_xprt, xprt);
     struct xdr_buf *xdr = &req->rq_snd_buf;
     rpc_fraghdr rm = xs_stream_record_marker(xdr);
     unsigned int msglen = rm ? req->rq_slen + sizeof(rm) : req->rq_slen;
     struct msghdr msg = {
         .msg_flags  = XS_SENDMSG_FLAGS,
     };
     bool vm_wait;
     unsigned int sent;
     int status;
 
     /* Close the stream if the previous transmission was incomplete */
     if (xs_send_request_was_aborted(transport, req)) {
         xprt_force_disconnect(xprt);
         return -ENOTCONN;
     }
 
     xs_pktdump("packet data:",
             req->rq_svec->iov_base, req->rq_svec->iov_len);
 
     vm_wait = sk_stream_is_writeable(transport->inet) ? true : false;
 
     req->rq_xtime = ktime_get();
     status = xprt_sock_sendmsg(transport->sock, &msg, xdr,
                    transport->xmit.offset, rm, &sent);
     dprintk("RPC:       %s(%u) = %d\n",
             __func__, xdr->len - transport->xmit.offset, status);
 
     if (likely(sent > 0) || status == 0) {
         transport->xmit.offset += sent;
         req->rq_bytes_sent = transport->xmit.offset;
         if (likely(req->rq_bytes_sent >= msglen)) {
             req->rq_xmit_bytes_sent += transport->xmit.offset;
             transport->xmit.offset = 0;
             return 0;
         }
         status = -EAGAIN;
         vm_wait = false;
     }
 
     switch (status) {
     case -EAGAIN:
         status = xs_stream_nospace(req, vm_wait);
         break;
     default:
         dprintk("RPC:       sendmsg returned unrecognized error %d\n",
             -status);
         fallthrough;
     case -EPIPE:
         xprt_force_disconnect(xprt);
         status = -ENOTCONN;
     }
 
     return status;
 }
 
 /**
  * xs_udp_send_request - write an RPC request to a UDP socket
  * @req: pointer to RPC request
  *
  * Return values:
  *        0:    The request has been sent
  *   EAGAIN:    The socket was blocked, please call again later to
  *      complete the request
  * ENOTCONN:    Caller needs to invoke connect logic then call again
  *    other:    Some other error occurred, the request was not sent
  */
 static int xs_udp_send_request(struct rpc_rqst *req)
 {
     struct rpc_xprt *xprt = req->rq_xprt;
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
     struct xdr_buf *xdr = &req->rq_snd_buf;
     struct msghdr msg = {
         .msg_name   = xs_addr(xprt),
         .msg_namelen    = xprt->addrlen,
         .msg_flags  = XS_SENDMSG_FLAGS,
     };
     unsigned int sent;
     int status;
 
     xs_pktdump("packet data:",
                 req->rq_svec->iov_base,
                 req->rq_svec->iov_len);
 
     if (!xprt_bound(xprt))
         return -ENOTCONN;
 
     if (!xprt_request_get_cong(xprt, req))
         return -EBADSLT;
 
     status = xdr_alloc_bvec(xdr, rpc_task_gfp_mask());
     if (status < 0)
         return status;
     req->rq_xtime = ktime_get();
     status = xprt_sock_sendmsg(transport->sock, &msg, xdr, 0, 0, &sent);
 
     dprintk("RPC:       xs_udp_send_request(%u) = %d\n",
             xdr->len, status);
 
     /* firewall is blocking us, don't return -EAGAIN or we end up looping */
     if (status == -EPERM)
         goto process_status;
 
     if (status == -EAGAIN && sock_writeable(transport->inet))
         status = -ENOBUFS;
 
     if (sent > 0 || status == 0) {
         req->rq_xmit_bytes_sent += sent;
         if (sent >= req->rq_slen)
             return 0;
         /* Still some bytes left; set up for a retry later. */
         status = -EAGAIN;
     }
 
 process_status:
     switch (status) {
     case -ENOTSOCK:
         status = -ENOTCONN;
         /* Should we call xs_close() here? */
         break;
     case -EAGAIN:
         status = xs_sock_nospace(req);
         break;
     case -ENETUNREACH:
     case -ENOBUFS:
     case -EPIPE:
     case -ECONNREFUSED:
     case -EPERM:
         /* When the server has died, an ICMP port unreachable message
          * prompts ECONNREFUSED. */
         break;
     default:
         dprintk("RPC:       sendmsg returned unrecognized error %d\n",
             -status);
     }
 
     return status;
 }
 
 /**
  * xs_tcp_send_request - write an RPC request to a TCP socket
  * @req: pointer to RPC request
  *
  * Return values:
  *        0:    The request has been sent
  *   EAGAIN:    The socket was blocked, please call again later to
  *      complete the request
  * ENOTCONN:    Caller needs to invoke connect logic then call again
  *    other:    Some other error occurred, the request was not sent
  *
  * XXX: In the case of soft timeouts, should we eventually give up
  *  if sendmsg is not able to make progress?
  */
 static int xs_tcp_send_request(struct rpc_rqst *req)
 {
     struct rpc_xprt *xprt = req->rq_xprt;
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
     struct xdr_buf *xdr = &req->rq_snd_buf;
     rpc_fraghdr rm = xs_stream_record_marker(xdr);
     unsigned int msglen = rm ? req->rq_slen + sizeof(rm) : req->rq_slen;
     struct msghdr msg = {
         .msg_flags  = XS_SENDMSG_FLAGS,
     };
     bool vm_wait;
     unsigned int sent;
     int status;
 
     /* Close the stream if the previous transmission was incomplete */
     if (xs_send_request_was_aborted(transport, req)) {
         if (transport->sock != NULL)
             kernel_sock_shutdown(transport->sock, SHUT_RDWR);
         return -ENOTCONN;
     }
     if (!transport->inet)
         return -ENOTCONN;
 
     xs_pktdump("packet data:",
                 req->rq_svec->iov_base,
                 req->rq_svec->iov_len);
 
     if (test_bit(XPRT_SOCK_UPD_TIMEOUT, &transport->sock_state))
         xs_tcp_set_socket_timeouts(xprt, transport->sock);
 
     xs_set_srcport(transport, transport->sock);
 
     /* Continue transmitting the packet/record. We must be careful
      * to cope with writespace callbacks arriving _after_ we have
      * called sendmsg(). */
     req->rq_xtime = ktime_get();
     tcp_sock_set_cork(transport->inet, true);
 
     vm_wait = sk_stream_is_writeable(transport->inet) ? true : false;
 
     do {
         status = xprt_sock_sendmsg(transport->sock, &msg, xdr,
                        transport->xmit.offset, rm, &sent);
 
         dprintk("RPC:       xs_tcp_send_request(%u) = %d\n",
                 xdr->len - transport->xmit.offset, status);
 
         /* If we've sent the entire packet, immediately
          * reset the count of bytes sent. */
         transport->xmit.offset += sent;
         req->rq_bytes_sent = transport->xmit.offset;
         if (likely(req->rq_bytes_sent >= msglen)) {
             req->rq_xmit_bytes_sent += transport->xmit.offset;
             transport->xmit.offset = 0;
             if (atomic_long_read(&xprt->xmit_queuelen) == 1)
                 tcp_sock_set_cork(transport->inet, false);
             return 0;
         }
 
         WARN_ON_ONCE(sent == 0 && status == 0);
 
         if (sent > 0)
             vm_wait = false;
 
     } while (status == 0);
 
     switch (status) {
     case -ENOTSOCK:
         status = -ENOTCONN;
         /* Should we call xs_close() here? */
         break;
     case -EAGAIN:
         status = xs_stream_nospace(req, vm_wait);
         break;
     case -ECONNRESET:
     case -ECONNREFUSED:
     case -ENOTCONN:
     case -EADDRINUSE:
     case -ENOBUFS:
     case -EPIPE:
         break;
     default:
         dprintk("RPC:       sendmsg returned unrecognized error %d\n",
             -status);
     }
 
     return status;
 }
 
 static void xs_save_old_callbacks(struct sock_xprt *transport, struct sock *sk)
 {
     transport->old_data_ready = sk->sk_data_ready;
     transport->old_state_change = sk->sk_state_change;
     transport->old_write_space = sk->sk_write_space;
     transport->old_error_report = sk->sk_error_report;
 }
 
 static void xs_restore_old_callbacks(struct sock_xprt *transport, struct sock *sk)
 {
     sk->sk_data_ready = transport->old_data_ready;
     sk->sk_state_change = transport->old_state_change;
     sk->sk_write_space = transport->old_write_space;
     sk->sk_error_report = transport->old_error_report;
 }
 
 static void xs_sock_reset_state_flags(struct rpc_xprt *xprt)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
 
     clear_bit(XPRT_SOCK_DATA_READY, &transport->sock_state);
     clear_bit(XPRT_SOCK_WAKE_ERROR, &transport->sock_state);
     clear_bit(XPRT_SOCK_WAKE_WRITE, &transport->sock_state);
     clear_bit(XPRT_SOCK_WAKE_DISCONNECT, &transport->sock_state);
     clear_bit(XPRT_SOCK_NOSPACE, &transport->sock_state);
 }
 
 static void xs_run_error_worker(struct sock_xprt *transport, unsigned int nr)
 {
     set_bit(nr, &transport->sock_state);
     queue_work(xprtiod_workqueue, &transport->error_worker);
 }
 
 static void xs_sock_reset_connection_flags(struct rpc_xprt *xprt)
 {
     xprt->connect_cookie++;
     smp_mb__before_atomic();
     clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
     clear_bit(XPRT_CLOSING, &xprt->state);
     xs_sock_reset_state_flags(xprt);
     smp_mb__after_atomic();
 }
 
 /**
  * xs_error_report - callback to handle TCP socket state errors
  * @sk: socket
  *
  * Note: we don't call sock_error() since there may be a rpc_task
  * using the socket, and so we don't want to clear sk->sk_err.
  */
 static void xs_error_report(struct sock *sk)
 {
     struct sock_xprt *transport;
     struct rpc_xprt *xprt;
 
     if (!(xprt = xprt_from_sock(sk)))
         return;
 
     transport = container_of(xprt, struct sock_xprt, xprt);
     transport->xprt_err = -sk->sk_err;
     if (transport->xprt_err == 0)
         return;
     dprintk("RPC:       xs_error_report client %p, error=%d...\n",
             xprt, -transport->xprt_err);
     trace_rpc_socket_error(xprt, sk->sk_socket, transport->xprt_err);
 
     /* barrier ensures xprt_err is set before XPRT_SOCK_WAKE_ERROR */
     smp_mb__before_atomic();
     xs_run_error_worker(transport, XPRT_SOCK_WAKE_ERROR);
 }
 
 static void xs_reset_transport(struct sock_xprt *transport)
 {
     struct socket *sock = transport->sock;
     struct sock *sk = transport->inet;
     struct rpc_xprt *xprt = &transport->xprt;
     struct file *filp = transport->file;
 
     if (sk == NULL)
         return;
     /*
      * Make sure we're calling this in a context from which it is safe
      * to call __fput_sync(). In practice that means rpciod and the
      * system workqueue.
      */
     if (!(current->flags & PF_WQ_WORKER)) {
         WARN_ON_ONCE(1);
         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
         return;
     }
 
     if (atomic_read(&transport->xprt.swapper))
         sk_clear_memalloc(sk);
 
     kernel_sock_shutdown(sock, SHUT_RDWR);
 
     mutex_lock(&transport->recv_mutex);
     lock_sock(sk);
     transport->inet = NULL;
     transport->sock = NULL;
     transport->file = NULL;
 
     sk->sk_user_data = NULL;
 
     xs_restore_old_callbacks(transport, sk);
     xprt_clear_connected(xprt);
     xs_sock_reset_connection_flags(xprt);
     /* Reset stream record info */
     xs_stream_reset_connect(transport);
     release_sock(sk);
     mutex_unlock(&transport->recv_mutex);
 
     trace_rpc_socket_close(xprt, sock);
     __fput_sync(filp);
 
     xprt_disconnect_done(xprt);
 }
 
 /**
  * xs_close - close a socket
  * @xprt: transport
  *
  * This is used when all requests are complete; ie, no DRC state remains
  * on the server we want to save.
  *
  * The caller _must_ be holding XPRT_LOCKED in order to avoid issues with
  * xs_reset_transport() zeroing the socket from underneath a writer.
  */
 static void xs_close(struct rpc_xprt *xprt)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
 
     dprintk("RPC:       xs_close xprt %p\n", xprt);
 
     xs_reset_transport(transport);
     xprt->reestablish_timeout = 0;
 }
 
 static void xs_inject_disconnect(struct rpc_xprt *xprt)
 {
     dprintk("RPC:       injecting transport disconnect on xprt=%p\n",
         xprt);
     xprt_disconnect_done(xprt);
 }
 
 static void xs_xprt_free(struct rpc_xprt *xprt)
 {
     xs_free_peer_addresses(xprt);
     xprt_free(xprt);
 }
 
 /**
  * xs_destroy - prepare to shutdown a transport
  * @xprt: doomed transport
  *
  */
 static void xs_destroy(struct rpc_xprt *xprt)
 {
     struct sock_xprt *transport = container_of(xprt,
             struct sock_xprt, xprt);
     dprintk("RPC:       xs_destroy xprt %p\n", xprt);
 
     cancel_delayed_work_sync(&transport->connect_worker);
     xs_close(xprt);
     cancel_work_sync(&transport->recv_worker);
     cancel_work_sync(&transport->error_worker);
     xs_xprt_free(xprt);
     module_put(THIS_MODULE);
 }
 
 /**
  * xs_udp_data_read_skb - receive callback for UDP sockets
  * @xprt: transport
  * @sk: socket
  * @skb: skbuff
  *
  */
 static void xs_udp_data_read_skb(struct rpc_xprt *xprt,
         struct sock *sk,
         struct sk_buff *skb)
 {
     struct rpc_task *task;
     struct rpc_rqst *rovr;
     int repsize, copied;
     u32 _xid;
     __be32 *xp;
 
     repsize = skb->len;
     if (repsize < 4) {
         dprintk("RPC:       impossible RPC reply size %d!\n", repsize);
         return;
     }
 
     /* Copy the XID from the skb... */
     xp = skb_header_pointer(skb, 0, sizeof(_xid), &_xid);
     if (xp == NULL)
         return;
 
     /* Look up and lock the request corresponding to the given XID */
     spin_lock(&xprt->queue_lock);
     rovr = xprt_lookup_rqst(xprt, *xp);
     if (!rovr)
         goto out_unlock;
     xprt_pin_rqst(rovr);
     xprt_update_rtt(rovr->rq_task);
     spin_unlock(&xprt->queue_lock);
     task = rovr->rq_task;
 
     if ((copied = rovr->rq_private_buf.buflen) > repsize)
         copied = repsize;
 
     /* Suck it into the iovec, verify checksum if not done by hw. */
     if (csum_partial_copy_to_xdr(&rovr->rq_private_buf, skb)) {
         spin_lock(&xprt->queue_lock);
         __UDPX_INC_STATS(sk, UDP_MIB_INERRORS);
         goto out_unpin;
     }
 
 
     spin_lock(&xprt->transport_lock);
     xprt_adjust_cwnd(xprt, task, copied);
     spin_unlock(&xprt->transport_lock);
     spin_lock(&xprt->queue_lock);
     xprt_complete_rqst(task, copied);
     __UDPX_INC_STATS(sk, UDP_MIB_INDATAGRAMS);
 out_unpin:
     xprt_unpin_rqst(rovr);
  out_unlock:
     spin_unlock(&xprt->queue_lock);
 }
 
 static void xs_udp_data_receive(struct sock_xprt *transport)
 {
     struct sk_buff *skb;
     struct sock *sk;
     int err;
 
     mutex_lock(&transport->recv_mutex);
     sk = transport->inet;
     if (sk == NULL)
         goto out;
     for (;;) {
         skb = skb_recv_udp(sk, MSG_DONTWAIT, &err);
         if (skb == NULL)
             break;
         xs_udp_data_read_skb(&transport->xprt, sk, skb);
         consume_skb(skb);
         cond_resched();
     }
     xs_poll_check_readable(transport);
 out:
     mutex_unlock(&transport->recv_mutex);
 }
 
 static void xs_udp_data_receive_workfn(struct work_struct *work)
 {
     struct sock_xprt *transport =
         container_of(work, struct sock_xprt, recv_worker);
     unsigned int pflags = memalloc_nofs_save();
 
     xs_udp_data_receive(transport);
     memalloc_nofs_restore(pflags);
 }
 
 /**
  * xs_data_ready - "data ready" callback for sockets
  * @sk: socket with data to read
  *
  */
 static void xs_data_ready(struct sock *sk)
 {
     struct rpc_xprt *xprt;
 
     xprt = xprt_from_sock(sk);
     if (xprt != NULL) {
         struct sock_xprt *transport = container_of(xprt,
                 struct sock_xprt, xprt);
 
         trace_xs_data_ready(xprt);
 
         transport->old_data_ready(sk);
         /* Any data means we had a useful conversation, so
          * then we don't need to delay the next reconnect
          */
         if (xprt->reestablish_timeout)
             xprt->reestablish_timeout = 0;
         if (!test_and_set_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))
             queue_work(xprtiod_workqueue, &transport->recv_worker);
     }
 }
 
 /*
  * Helper function to force a TCP close if the server is sending
  * junk and/or it has put us in CLOSE_WAIT
  */
 static void xs_tcp_force_close(struct rpc_xprt *xprt)
 {
     xprt_force_disconnect(xprt);
 }
 
 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
 static size_t xs_tcp_bc_maxpayload(struct rpc_xprt *xprt)
 {
     return PAGE_SIZE;
 }
 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
 
 /**
  * xs_local_state_change - callback to handle AF_LOCAL socket state changes
  * @sk: socket whose state has changed
  *
  */
 static void xs_local_state_change(struct sock *sk)
 {
     struct rpc_xprt *xprt;
     struct sock_xprt *transport;
 
     if (!(xprt = xprt_from_sock(sk)))
         return;
     transport = container_of(xprt, struct sock_xprt, xprt);
     if (sk->sk_shutdown & SHUTDOWN_MASK) {
         clear_bit(XPRT_CONNECTED, &xprt->state);
         /* Trigger the socket release */
         xs_run_error_worker(transport, XPRT_SOCK_WAKE_DISCONNECT);
     }
 }
 
 /**
  * xs_tcp_state_change - callback to handle TCP socket state changes
  * @sk: socket whose state has changed
  *
  */
 static void xs_tcp_state_change(struct sock *sk)
 {
     struct rpc_xprt *xprt;
     struct sock_xprt *transport;
 
     if (!(xprt = xprt_from_sock(sk)))
         return;
     dprintk("RPC:       xs_tcp_state_change client %p...\n", xprt);
     dprintk("RPC:       state %x conn %d dead %d zapped %d sk_shutdown %d\n",
             sk->sk_state, xprt_connected(xprt),
             sock_flag(sk, SOCK_DEAD),
             sock_flag(sk, SOCK_ZAPPED),
             sk->sk_shutdown);
 
     transport = container_of(xprt, struct sock_xprt, xprt);
     trace_rpc_socket_state_change(xprt, sk->sk_socket);
     switch (sk->sk_state) {
     case TCP_ESTABLISHED:
         if (!xprt_test_and_set_connected(xprt)) {
             xprt->connect_cookie++;
             clear_bit(XPRT_SOCK_CONNECTING, &transport->sock_state);
             xprt_clear_connecting(xprt);
 
             xprt->stat.connect_count++;
             xprt->stat.connect_time += (long)jiffies -
                            xprt->stat.connect_start;
             xs_run_error_worker(transport, XPRT_SOCK_WAKE_PENDING);
         }
         break;
     case TCP_FIN_WAIT1:
         /* The client initiated a shutdown of the socket */
         xprt->connect_cookie++;
         xprt->reestablish_timeout = 0;
         set_bit(XPRT_CLOSING, &xprt->state);
         smp_mb__before_atomic();
         clear_bit(XPRT_CONNECTED, &xprt->state);
         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
         smp_mb__after_atomic();
         break;
     case TCP_CLOSE_WAIT:
         /* The server initiated a shutdown of the socket */
         xprt->connect_cookie++;
         clear_bit(XPRT_CONNECTED, &xprt->state);
         xs_run_error_worker(transport, XPRT_SOCK_WAKE_DISCONNECT);
         fallthrough;
     case TCP_CLOSING:
         /*
          * If the server closed down the connection, make sure that
          * we back off before reconnecting
          */
         if (xprt->reestablish_timeout < XS_TCP_INIT_REEST_TO)
             xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
         break;
     case TCP_LAST_ACK:
         set_bit(XPRT_CLOSING, &xprt->state);
         smp_mb__before_atomic();
         clear_bit(XPRT_CONNECTED, &xprt->state);
         smp_mb__after_atomic();
         break;
     case TCP_CLOSE:
         if (test_and_clear_bit(XPRT_SOCK_CONNECTING,
                     &transport->sock_state))
             xprt_clear_connecting(xprt);
         clear_bit(XPRT_CLOSING, &xprt->state);
         /* Trigger the socket release */
         xs_run_error_worker(transport, XPRT_SOCK_WAKE_DISCONNECT);
     }
 }
 
 static void xs_write_space(struct sock *sk)
 {
     struct sock_xprt *transport;
     struct rpc_xprt *xprt;
 
     if (!sk->sk_socket)
         return;
     clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 
     if (unlikely(!(xprt = xprt_from_sock(sk))))
         return;
     transport = container_of(xprt, struct sock_xprt, xprt);
     if (!test_and_clear_bit(XPRT_SOCK_NOSPACE, &transport->sock_state))
         return;
     xs_run_error_worker(transport, XPRT_SOCK_WAKE_WRITE);
     sk->sk_write_pending--;
 }
 
 /**
  * xs_udp_write_space - callback invoked when socket buffer space
  *                             becomes available
  * @sk: socket whose state has changed
  *
  * Called when more output buffer space is available for this socket.
  * We try not to wake our writers until they can make "significant"
  * progress, otherwise we'll waste resources thrashing kernel_sendmsg
  * with a bunch of small requests.
  */
 static void xs_udp_write_space(struct sock *sk)
 {
     /* from net/core/sock.c:sock_def_write_space */
     if (sock_writeable(sk))
         xs_write_space(sk);
 }
 
 /**
  * xs_tcp_write_space - callback invoked when socket buffer space
  *                             becomes available
  * @sk: socket whose state has changed
  *
  * Called when more output buffer space is available for this socket.
  * We try not to wake our writers until they can make "significant"
  * progress, otherwise we'll waste resources thrashing kernel_sendmsg
  * with a bunch of small requests.
  */
 static void xs_tcp_write_space(struct sock *sk)
 {
     /* from net/core/stream.c:sk_stream_write_space */
     if (sk_stream_is_writeable(sk))
         xs_write_space(sk);
 }
 
 static void xs_udp_do_set_buffer_size(struct rpc_xprt *xprt)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
     struct sock *sk = transport->inet;
 
     if (transport->rcvsize) {
         sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
         sk->sk_rcvbuf = transport->rcvsize * xprt->max_reqs * 2;
     }
     if (transport->sndsize) {
         sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
         sk->sk_sndbuf = transport->sndsize * xprt->max_reqs * 2;
         sk->sk_write_space(sk);
     }
 }
 
 /**
  * xs_udp_set_buffer_size - set send and receive limits
  * @xprt: generic transport
  * @sndsize: requested size of send buffer, in bytes
  * @rcvsize: requested size of receive buffer, in bytes
  *
  * Set socket send and receive buffer size limits.
  */
 static void xs_udp_set_buffer_size(struct rpc_xprt *xprt, size_t sndsize, size_t rcvsize)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
 
     transport->sndsize = 0;
     if (sndsize)
         transport->sndsize = sndsize + 1024;
     transport->rcvsize = 0;
     if (rcvsize)
         transport->rcvsize = rcvsize + 1024;
 
     xs_udp_do_set_buffer_size(xprt);
 }
 
 /**
  * xs_udp_timer - called when a retransmit timeout occurs on a UDP transport
  * @xprt: controlling transport
  * @task: task that timed out
  *
  * Adjust the congestion window after a retransmit timeout has occurred.
  */
 static void xs_udp_timer(struct rpc_xprt *xprt, struct rpc_task *task)
 {
     spin_lock(&xprt->transport_lock);
     xprt_adjust_cwnd(xprt, task, -ETIMEDOUT);
     spin_unlock(&xprt->transport_lock);
 }
 
 static int xs_get_random_port(void)
 {
     unsigned short min = xprt_min_resvport, max = xprt_max_resvport;
     unsigned short range;
     unsigned short rand;
 
     if (max < min)
         return -EADDRINUSE;
     range = max - min + 1;
     rand = (unsigned short) prandom_u32() % range;
     return rand + min;
 }
 
 static unsigned short xs_sock_getport(struct socket *sock)
 {
     struct sockaddr_storage buf;
     unsigned short port = 0;
 
     if (kernel_getsockname(sock, (struct sockaddr *)&buf) < 0)
         goto out;
     switch (buf.ss_family) {
     case AF_INET6:
         port = ntohs(((struct sockaddr_in6 *)&buf)->sin6_port);
         break;
     case AF_INET:
         port = ntohs(((struct sockaddr_in *)&buf)->sin_port);
     }
 out:
     return port;
 }
 
 /**
  * xs_set_port - reset the port number in the remote endpoint address
  * @xprt: generic transport
  * @port: new port number
  *
  */
 static void xs_set_port(struct rpc_xprt *xprt, unsigned short port)
 {
     dprintk("RPC:       setting port for xprt %p to %u\n", xprt, port);
 
     rpc_set_port(xs_addr(xprt), port);
     xs_update_peer_port(xprt);
 }
 
 static void xs_set_srcport(struct sock_xprt *transport, struct socket *sock)
 {
     if (transport->srcport == 0 && transport->xprt.reuseport)
         transport->srcport = xs_sock_getport(sock);
 }
 
 static int xs_get_srcport(struct sock_xprt *transport)
 {
     int port = transport->srcport;
 
     if (port == 0 && transport->xprt.resvport)
         port = xs_get_random_port();
     return port;
 }
 
 static unsigned short xs_sock_srcport(struct rpc_xprt *xprt)
 {
     struct sock_xprt *sock = container_of(xprt, struct sock_xprt, xprt);
     unsigned short ret = 0;
     mutex_lock(&sock->recv_mutex);
     if (sock->sock)
         ret = xs_sock_getport(sock->sock);
     mutex_unlock(&sock->recv_mutex);
     return ret;
 }
 
 static int xs_sock_srcaddr(struct rpc_xprt *xprt, char *buf, size_t buflen)
 {
     struct sock_xprt *sock = container_of(xprt, struct sock_xprt, xprt);
     union {
         struct sockaddr sa;
         struct sockaddr_storage st;
     } saddr;
     int ret = -ENOTCONN;
 
     mutex_lock(&sock->recv_mutex);
     if (sock->sock) {
         ret = kernel_getsockname(sock->sock, &saddr.sa);
         if (ret >= 0)
             ret = snprintf(buf, buflen, "%pISc", &saddr.sa);
     }
     mutex_unlock(&sock->recv_mutex);
     return ret;
 }
 
 static unsigned short xs_next_srcport(struct sock_xprt *transport, unsigned short port)
 {
     if (transport->srcport != 0)
         transport->srcport = 0;
     if (!transport->xprt.resvport)
         return 0;
     if (port <= xprt_min_resvport || port > xprt_max_resvport)
         return xprt_max_resvport;
     return --port;
 }
 static int xs_bind(struct sock_xprt *transport, struct socket *sock)
 {
     struct sockaddr_storage myaddr;
     int err, nloop = 0;
     int port = xs_get_srcport(transport);
     unsigned short last;
 
     /*
      * If we are asking for any ephemeral port (i.e. port == 0 &&
      * transport->xprt.resvport == 0), don't bind.  Let the local
      * port selection happen implicitly when the socket is used
      * (for example at connect time).
      *
      * This ensures that we can continue to establish TCP
      * connections even when all local ephemeral ports are already
      * a part of some TCP connection.  This makes no difference
      * for UDP sockets, but also doesn't harm them.
      *
      * If we're asking for any reserved port (i.e. port == 0 &&
      * transport->xprt.resvport == 1) xs_get_srcport above will
      * ensure that port is non-zero and we will bind as needed.
      */
     if (port <= 0)
         return port;
 
     memcpy(&myaddr, &transport->srcaddr, transport->xprt.addrlen);
     do {
         rpc_set_port((struct sockaddr *)&myaddr, port);
         err = kernel_bind(sock, (struct sockaddr *)&myaddr,
                 transport->xprt.addrlen);
         if (err == 0) {
             if (transport->xprt.reuseport)
                 transport->srcport = port;
             break;
         }
         last = port;
         port = xs_next_srcport(transport, port);
         if (port > last)
             nloop++;
     } while (err == -EADDRINUSE && nloop != 2);
 
     if (myaddr.ss_family == AF_INET)
         dprintk("RPC:       %s %pI4:%u: %s (%d)\n", __func__,
                 &((struct sockaddr_in *)&myaddr)->sin_addr,
                 port, err ? "failed" : "ok", err);
     else
         dprintk("RPC:       %s %pI6:%u: %s (%d)\n", __func__,
                 &((struct sockaddr_in6 *)&myaddr)->sin6_addr,
                 port, err ? "failed" : "ok", err);
     return err;
 }
 
 /*
  * We don't support autobind on AF_LOCAL sockets
  */
 static void xs_local_rpcbind(struct rpc_task *task)
 {
     xprt_set_bound(task->tk_xprt);
 }
 
 static void xs_local_set_port(struct rpc_xprt *xprt, unsigned short port)
 {
 }
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 static struct lock_class_key xs_key[3];
 static struct lock_class_key xs_slock_key[3];
 
 static inline void xs_reclassify_socketu(struct socket *sock)
 {
     struct sock *sk = sock->sk;
 
     sock_lock_init_class_and_name(sk, "slock-AF_LOCAL-RPC",
         &xs_slock_key[0], "sk_lock-AF_LOCAL-RPC", &xs_key[0]);
 }
 
 static inline void xs_reclassify_socket4(struct socket *sock)
 {
     struct sock *sk = sock->sk;
 
     sock_lock_init_class_and_name(sk, "slock-AF_INET-RPC",
         &xs_slock_key[1], "sk_lock-AF_INET-RPC", &xs_key[1]);
 }
 
 static inline void xs_reclassify_socket6(struct socket *sock)
 {
     struct sock *sk = sock->sk;
 
     sock_lock_init_class_and_name(sk, "slock-AF_INET6-RPC",
         &xs_slock_key[2], "sk_lock-AF_INET6-RPC", &xs_key[2]);
 }
 
 static inline void xs_reclassify_socket(int family, struct socket *sock)
 {
     if (WARN_ON_ONCE(!sock_allow_reclassification(sock->sk)))
         return;
 
     switch (family) {
     case AF_LOCAL:
         xs_reclassify_socketu(sock);
         break;
     case AF_INET:
         xs_reclassify_socket4(sock);
         break;
     case AF_INET6:
         xs_reclassify_socket6(sock);
         break;
     }
 }
 #else
 static inline void xs_reclassify_socket(int family, struct socket *sock)
 {
 }
 #endif
 
 static void xs_dummy_setup_socket(struct work_struct *work)
 {
 }
 
 static struct socket *xs_create_sock(struct rpc_xprt *xprt,
         struct sock_xprt *transport, int family, int type,
         int protocol, bool reuseport)
 {
     struct file *filp;
     struct socket *sock;
     int err;
 
     err = __sock_create(xprt->xprt_net, family, type, protocol, &sock, 1);
     if (err < 0) {
         dprintk("RPC:       can't create %d transport socket (%d).\n",
                 protocol, -err);
         goto out;
     }
     xs_reclassify_socket(family, sock);
 
     if (reuseport)
         sock_set_reuseport(sock->sk);
 
     err = xs_bind(transport, sock);
     if (err) {
         sock_release(sock);
         goto out;
     }
 
     filp = sock_alloc_file(sock, O_NONBLOCK, NULL);
     if (IS_ERR(filp))
         return ERR_CAST(filp);
     transport->file = filp;
 
     return sock;
 out:
     return ERR_PTR(err);
 }
 
 static int xs_local_finish_connecting(struct rpc_xprt *xprt,
                       struct socket *sock)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt,
                                     xprt);
 
     if (!transport->inet) {
         struct sock *sk = sock->sk;
 
         lock_sock(sk);
 
         xs_save_old_callbacks(transport, sk);
 
         sk->sk_user_data = xprt;
         sk->sk_data_ready = xs_data_ready;
         sk->sk_write_space = xs_udp_write_space;
         sk->sk_state_change = xs_local_state_change;
         sk->sk_error_report = xs_error_report;
 
         xprt_clear_connected(xprt);
 
         /* Reset to new socket */
         transport->sock = sock;
         transport->inet = sk;
 
         release_sock(sk);
     }
 
     xs_stream_start_connect(transport);
 
     return kernel_connect(sock, xs_addr(xprt), xprt->addrlen, 0);
 }
 
 /**
  * xs_local_setup_socket - create AF_LOCAL socket, connect to a local endpoint
  * @transport: socket transport to connect
  */
 static int xs_local_setup_socket(struct sock_xprt *transport)
 {
     struct rpc_xprt *xprt = &transport->xprt;
     struct file *filp;
     struct socket *sock;
     int status;
 
     status = __sock_create(xprt->xprt_net, AF_LOCAL,
                     SOCK_STREAM, 0, &sock, 1);
     if (status < 0) {
         dprintk("RPC:       can't create AF_LOCAL "
             "transport socket (%d).\n", -status);
         goto out;
     }
     xs_reclassify_socket(AF_LOCAL, sock);
 
     filp = sock_alloc_file(sock, O_NONBLOCK, NULL);
     if (IS_ERR(filp)) {
         status = PTR_ERR(filp);
         goto out;
     }
     transport->file = filp;
 
     dprintk("RPC:       worker connecting xprt %p via AF_LOCAL to %s\n",
             xprt, xprt->address_strings[RPC_DISPLAY_ADDR]);
 
     status = xs_local_finish_connecting(xprt, sock);
     trace_rpc_socket_connect(xprt, sock, status);
     switch (status) {
     case 0:
         dprintk("RPC:       xprt %p connected to %s\n",
                 xprt, xprt->address_strings[RPC_DISPLAY_ADDR]);
         xprt->stat.connect_count++;
         xprt->stat.connect_time += (long)jiffies -
                        xprt->stat.connect_start;
         xprt_set_connected(xprt);
         break;
     case -ENOBUFS:
         break;
     case -ENOENT:
         dprintk("RPC:       xprt %p: socket %s does not exist\n",
                 xprt, xprt->address_strings[RPC_DISPLAY_ADDR]);
         break;
     case -ECONNREFUSED:
         dprintk("RPC:       xprt %p: connection refused for %s\n",
                 xprt, xprt->address_strings[RPC_DISPLAY_ADDR]);
         break;
     default:
         printk(KERN_ERR "%s: unhandled error (%d) connecting to %s\n",
                 __func__, -status,
                 xprt->address_strings[RPC_DISPLAY_ADDR]);
     }
 
 out:
     xprt_clear_connecting(xprt);
     xprt_wake_pending_tasks(xprt, status);
     return status;
 }
 
 static void xs_local_connect(struct rpc_xprt *xprt, struct rpc_task *task)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
     int ret;
 
     if (transport->file)
         goto force_disconnect;
 
     if (RPC_IS_ASYNC(task)) {
         /*
          * We want the AF_LOCAL connect to be resolved in the
          * filesystem namespace of the process making the rpc
          * call.  Thus we connect synchronously.
          *
          * If we want to support asynchronous AF_LOCAL calls,
          * we'll need to figure out how to pass a namespace to
          * connect.
          */
         task->tk_rpc_status = -ENOTCONN;
         rpc_exit(task, -ENOTCONN);
         goto out_wake;
     }
     ret = xs_local_setup_socket(transport);
     if (ret && !RPC_IS_SOFTCONN(task))
         msleep_interruptible(15000);
     return;
 force_disconnect:
     xprt_force_disconnect(xprt);
 out_wake:
     xprt_clear_connecting(xprt);
     xprt_wake_pending_tasks(xprt, -ENOTCONN);
 }
 
 #if IS_ENABLED(CONFIG_SUNRPC_SWAP)
 /*
  * Note that this should be called with XPRT_LOCKED held, or recv_mutex
  * held, or when we otherwise know that we have exclusive access to the
  * socket, to guard against races with xs_reset_transport.
  */
 static void xs_set_memalloc(struct rpc_xprt *xprt)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt,
             xprt);
 
     /*
      * If there's no sock, then we have nothing to set. The
      * reconnecting process will get it for us.
      */
     if (!transport->inet)
         return;
     if (atomic_read(&xprt->swapper))
         sk_set_memalloc(transport->inet);
 }
 
 /**
  * xs_enable_swap - Tag this transport as being used for swap.
  * @xprt: transport to tag
  *
  * Take a reference to this transport on behalf of the rpc_clnt, and
  * optionally mark it for swapping if it wasn't already.
  */
 static int
 xs_enable_swap(struct rpc_xprt *xprt)
 {
     struct sock_xprt *xs = container_of(xprt, struct sock_xprt, xprt);
 
     mutex_lock(&xs->recv_mutex);
     if (atomic_inc_return(&xprt->swapper) == 1 &&
         xs->inet)
         sk_set_memalloc(xs->inet);
     mutex_unlock(&xs->recv_mutex);
     return 0;
 }
 
 /**
  * xs_disable_swap - Untag this transport as being used for swap.
  * @xprt: transport to tag
  *
  * Drop a "swapper" reference to this xprt on behalf of the rpc_clnt. If the
  * swapper refcount goes to 0, untag the socket as a memalloc socket.
  */
 static void
 xs_disable_swap(struct rpc_xprt *xprt)
 {
     struct sock_xprt *xs = container_of(xprt, struct sock_xprt, xprt);
 
     mutex_lock(&xs->recv_mutex);
     if (atomic_dec_and_test(&xprt->swapper) &&
         xs->inet)
         sk_clear_memalloc(xs->inet);
     mutex_unlock(&xs->recv_mutex);
 }
 #else
 static void xs_set_memalloc(struct rpc_xprt *xprt)
 {
 }
 
 static int
 xs_enable_swap(struct rpc_xprt *xprt)
 {
     return -EINVAL;
 }
 
 static void
 xs_disable_swap(struct rpc_xprt *xprt)
 {
 }
 #endif
 
 static void xs_udp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
 
     if (!transport->inet) {
         struct sock *sk = sock->sk;
 
         lock_sock(sk);
 
         xs_save_old_callbacks(transport, sk);
 
         sk->sk_user_data = xprt;
         sk->sk_data_ready = xs_data_ready;
         sk->sk_write_space = xs_udp_write_space;
 
         xprt_set_connected(xprt);
 
         /* Reset to new socket */
         transport->sock = sock;
         transport->inet = sk;
 
         xs_set_memalloc(xprt);
 
         release_sock(sk);
     }
     xs_udp_do_set_buffer_size(xprt);
 
     xprt->stat.connect_start = jiffies;
 }
 
 static void xs_udp_setup_socket(struct work_struct *work)
 {
     struct sock_xprt *transport =
         container_of(work, struct sock_xprt, connect_worker.work);
     struct rpc_xprt *xprt = &transport->xprt;
     struct socket *sock;
     int status = -EIO;
     unsigned int pflags = current->flags;
 
     if (atomic_read(&xprt->swapper))
         current->flags |= PF_MEMALLOC;
     sock = xs_create_sock(xprt, transport,
             xs_addr(xprt)->sa_family, SOCK_DGRAM,
             IPPROTO_UDP, false);
     if (IS_ERR(sock))
         goto out;
 
     dprintk("RPC:       worker connecting xprt %p via %s to "
                 "%s (port %s)\n", xprt,
             xprt->address_strings[RPC_DISPLAY_PROTO],
             xprt->address_strings[RPC_DISPLAY_ADDR],
             xprt->address_strings[RPC_DISPLAY_PORT]);
 
     xs_udp_finish_connecting(xprt, sock);
     trace_rpc_socket_connect(xprt, sock, 0);
     status = 0;
 out:
     xprt_clear_connecting(xprt);
     xprt_unlock_connect(xprt, transport);
     xprt_wake_pending_tasks(xprt, status);
     current_restore_flags(pflags, PF_MEMALLOC);
 }
 
 /**
  * xs_tcp_shutdown - gracefully shut down a TCP socket
  * @xprt: transport
  *
  * Initiates a graceful shutdown of the TCP socket by calling the
  * equivalent of shutdown(SHUT_RDWR);
  */
 static void xs_tcp_shutdown(struct rpc_xprt *xprt)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
     struct socket *sock = transport->sock;
     int skst = transport->inet ? transport->inet->sk_state : TCP_CLOSE;
 
     if (sock == NULL)
         return;
     if (!xprt->reuseport) {
         xs_close(xprt);
         return;
     }
     switch (skst) {
     case TCP_FIN_WAIT1:
     case TCP_FIN_WAIT2:
         break;
     case TCP_ESTABLISHED:
     case TCP_CLOSE_WAIT:
         kernel_sock_shutdown(sock, SHUT_RDWR);
         trace_rpc_socket_shutdown(xprt, sock);
         break;
     default:
         xs_reset_transport(transport);
     }
 }
 
 static void xs_tcp_set_socket_timeouts(struct rpc_xprt *xprt,
         struct socket *sock)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
     unsigned int keepidle;
     unsigned int keepcnt;
     unsigned int timeo;
 
     spin_lock(&xprt->transport_lock);
     keepidle = DIV_ROUND_UP(xprt->timeout->to_initval, HZ);
     keepcnt = xprt->timeout->to_retries + 1;
     timeo = jiffies_to_msecs(xprt->timeout->to_initval) *
         (xprt->timeout->to_retries + 1);
     clear_bit(XPRT_SOCK_UPD_TIMEOUT, &transport->sock_state);
     spin_unlock(&xprt->transport_lock);
 
     /* TCP Keepalive options */
     sock_set_keepalive(sock->sk);
     tcp_sock_set_keepidle(sock->sk, keepidle);
     tcp_sock_set_keepintvl(sock->sk, keepidle);
     tcp_sock_set_keepcnt(sock->sk, keepcnt);
 
     /* TCP user timeout (see RFC5482) */
     tcp_sock_set_user_timeout(sock->sk, timeo);
 }
 
 static void xs_tcp_set_connect_timeout(struct rpc_xprt *xprt,
         unsigned long connect_timeout,
         unsigned long reconnect_timeout)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
     struct rpc_timeout to;
     unsigned long initval;
 
     spin_lock(&xprt->transport_lock);
     if (reconnect_timeout < xprt->max_reconnect_timeout)
         xprt->max_reconnect_timeout = reconnect_timeout;
     if (connect_timeout < xprt->connect_timeout) {
         memcpy(&to, xprt->timeout, sizeof(to));
         initval = DIV_ROUND_UP(connect_timeout, to.to_retries + 1);
         /* Arbitrary lower limit */
         if (initval <  XS_TCP_INIT_REEST_TO << 1)
             initval = XS_TCP_INIT_REEST_TO << 1;
         to.to_initval = initval;
         to.to_maxval = initval;
         memcpy(&transport->tcp_timeout, &to,
                 sizeof(transport->tcp_timeout));
         xprt->timeout = &transport->tcp_timeout;
         xprt->connect_timeout = connect_timeout;
     }
     set_bit(XPRT_SOCK_UPD_TIMEOUT, &transport->sock_state);
     spin_unlock(&xprt->transport_lock);
 }
 
 static int xs_tcp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
 
     if (!transport->inet) {
         struct sock *sk = sock->sk;
 
         /* Avoid temporary address, they are bad for long-lived
          * connections such as NFS mounts.
          * RFC4941, section 3.6 suggests that:
          *    Individual applications, which have specific
          *    knowledge about the normal duration of connections,
          *    MAY override this as appropriate.
          */
         if (xs_addr(xprt)->sa_family == PF_INET6) {
             ip6_sock_set_addr_preferences(sk,
                 IPV6_PREFER_SRC_PUBLIC);
         }
 
         xs_tcp_set_socket_timeouts(xprt, sock);
         tcp_sock_set_nodelay(sk);
 
         lock_sock(sk);
 
         xs_save_old_callbacks(transport, sk);
 
         sk->sk_user_data = xprt;
         sk->sk_data_ready = xs_data_ready;
         sk->sk_state_change = xs_tcp_state_change;
         sk->sk_write_space = xs_tcp_write_space;
         sk->sk_error_report = xs_error_report;
 
         /* socket options */
         sock_reset_flag(sk, SOCK_LINGER);
 
         xprt_clear_connected(xprt);
 
         /* Reset to new socket */
         transport->sock = sock;
         transport->inet = sk;
 
         release_sock(sk);
     }
 
     if (!xprt_bound(xprt))
         return -ENOTCONN;
 
     xs_set_memalloc(xprt);
 
     xs_stream_start_connect(transport);
 
     /* Tell the socket layer to start connecting... */
     set_bit(XPRT_SOCK_CONNECTING, &transport->sock_state);
     return kernel_connect(sock, xs_addr(xprt), xprt->addrlen, O_NONBLOCK);
 }
 
 /**
  * xs_tcp_setup_socket - create a TCP socket and connect to a remote endpoint
  * @work: queued work item
  *
  * Invoked by a work queue tasklet.
  */
 static void xs_tcp_setup_socket(struct work_struct *work)
 {
     struct sock_xprt *transport =
         container_of(work, struct sock_xprt, connect_worker.work);
     struct socket *sock = transport->sock;
     struct rpc_xprt *xprt = &transport->xprt;
     int status;
     unsigned int pflags = current->flags;
 
     if (atomic_read(&xprt->swapper))
         current->flags |= PF_MEMALLOC;
 
     if (xprt_connected(xprt))
         goto out;
     if (test_and_clear_bit(XPRT_SOCK_CONNECT_SENT,
                    &transport->sock_state) ||
         !sock) {
         xs_reset_transport(transport);
         sock = xs_create_sock(xprt, transport, xs_addr(xprt)->sa_family,
                       SOCK_STREAM, IPPROTO_TCP, true);
         if (IS_ERR(sock)) {
             xprt_wake_pending_tasks(xprt, PTR_ERR(sock));
             goto out;
         }
     }
 
     dprintk("RPC:       worker connecting xprt %p via %s to "
                 "%s (port %s)\n", xprt,
             xprt->address_strings[RPC_DISPLAY_PROTO],
             xprt->address_strings[RPC_DISPLAY_ADDR],
             xprt->address_strings[RPC_DISPLAY_PORT]);
 
     status = xs_tcp_finish_connecting(xprt, sock);
     trace_rpc_socket_connect(xprt, sock, status);
     dprintk("RPC:       %p connect status %d connected %d sock state %d\n",
             xprt, -status, xprt_connected(xprt),
             sock->sk->sk_state);
     switch (status) {
     case 0:
     case -EINPROGRESS:
         /* SYN_SENT! */
         set_bit(XPRT_SOCK_CONNECT_SENT, &transport->sock_state);
         if (xprt->reestablish_timeout < XS_TCP_INIT_REEST_TO)
             xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
         fallthrough;
     case -EALREADY:
         goto out_unlock;
     case -EADDRNOTAVAIL:
         /* Source port number is unavailable. Try a new one! */
         transport->srcport = 0;
         status = -EAGAIN;
         break;
     case -EINVAL:
         /* Happens, for instance, if the user specified a link
          * local IPv6 address without a scope-id.
          */
     case -ECONNREFUSED:
     case -ECONNRESET:
     case -ENETDOWN:
     case -ENETUNREACH:
     case -EHOSTUNREACH:
     case -EADDRINUSE:
     case -ENOBUFS:
         break;
     default:
         printk("%s: connect returned unhandled error %d\n",
             __func__, status);
         status = -EAGAIN;
     }
 
     /* xs_tcp_force_close() wakes tasks with a fixed error code.
      * We need to wake them first to ensure the correct error code.
      */
     xprt_wake_pending_tasks(xprt, status);
     xs_tcp_force_close(xprt);
 out:
     xprt_clear_connecting(xprt);
 out_unlock:
     xprt_unlock_connect(xprt, transport);
     current_restore_flags(pflags, PF_MEMALLOC);
 }
 
 /**
  * xs_connect - connect a socket to a remote endpoint
  * @xprt: pointer to transport structure
  * @task: address of RPC task that manages state of connect request
  *
  * TCP: If the remote end dropped the connection, delay reconnecting.
  *
  * UDP socket connects are synchronous, but we use a work queue anyway
  * to guarantee that even unprivileged user processes can set up a
  * socket on a privileged port.
  *
  * If a UDP socket connect fails, the delay behavior here prevents
  * retry floods (hard mounts).
  */
 static void xs_connect(struct rpc_xprt *xprt, struct rpc_task *task)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
     unsigned long delay = 0;
 
     WARN_ON_ONCE(!xprt_lock_connect(xprt, task, transport));
 
     if (transport->sock != NULL) {
         dprintk("RPC:       xs_connect delayed xprt %p for %lu "
             "seconds\n", xprt, xprt->reestablish_timeout / HZ);
 
         delay = xprt_reconnect_delay(xprt);
         xprt_reconnect_backoff(xprt, XS_TCP_INIT_REEST_TO);
 
     } else
         dprintk("RPC:       xs_connect scheduled xprt %p\n", xprt);
 
     queue_delayed_work(xprtiod_workqueue,
             &transport->connect_worker,
             delay);
 }
 
 static void xs_wake_disconnect(struct sock_xprt *transport)
 {
     if (test_and_clear_bit(XPRT_SOCK_WAKE_DISCONNECT, &transport->sock_state))
         xs_tcp_force_close(&transport->xprt);
 }
 
 static void xs_wake_write(struct sock_xprt *transport)
 {
     if (test_and_clear_bit(XPRT_SOCK_WAKE_WRITE, &transport->sock_state))
         xprt_write_space(&transport->xprt);
 }
 
 static void xs_wake_error(struct sock_xprt *transport)
 {
     int sockerr;
 
     if (!test_bit(XPRT_SOCK_WAKE_ERROR, &transport->sock_state))
         return;
     mutex_lock(&transport->recv_mutex);
     if (transport->sock == NULL)
         goto out;
     if (!test_and_clear_bit(XPRT_SOCK_WAKE_ERROR, &transport->sock_state))
         goto out;
     sockerr = xchg(&transport->xprt_err, 0);
     if (sockerr < 0)
         xprt_wake_pending_tasks(&transport->xprt, sockerr);
 out:
     mutex_unlock(&transport->recv_mutex);
 }
 
 static void xs_wake_pending(struct sock_xprt *transport)
 {
     if (test_and_clear_bit(XPRT_SOCK_WAKE_PENDING, &transport->sock_state))
         xprt_wake_pending_tasks(&transport->xprt, -EAGAIN);
 }
 
 static void xs_error_handle(struct work_struct *work)
 {
     struct sock_xprt *transport = container_of(work,
             struct sock_xprt, error_worker);
 
     xs_wake_disconnect(transport);
     xs_wake_write(transport);
     xs_wake_error(transport);
     xs_wake_pending(transport);
 }
 
 /**
  * xs_local_print_stats - display AF_LOCAL socket-specific stats
  * @xprt: rpc_xprt struct containing statistics
  * @seq: output file
  *
  */
 static void xs_local_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
 {
     long idle_time = 0;
 
     if (xprt_connected(xprt))
         idle_time = (long)(jiffies - xprt->last_used) / HZ;
 
     seq_printf(seq, "\txprt:\tlocal %lu %lu %lu %ld %lu %lu %lu "
             "%llu %llu %lu %llu %llu\n",
             xprt->stat.bind_count,
             xprt->stat.connect_count,
             xprt->stat.connect_time / HZ,
             idle_time,
             xprt->stat.sends,
             xprt->stat.recvs,
             xprt->stat.bad_xids,
             xprt->stat.req_u,
             xprt->stat.bklog_u,
             xprt->stat.max_slots,
             xprt->stat.sending_u,
             xprt->stat.pending_u);
 }
 
 /**
  * xs_udp_print_stats - display UDP socket-specific stats
  * @xprt: rpc_xprt struct containing statistics
  * @seq: output file
  *
  */
 static void xs_udp_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
 
     seq_printf(seq, "\txprt:\tudp %u %lu %lu %lu %lu %llu %llu "
             "%lu %llu %llu\n",
             transport->srcport,
             xprt->stat.bind_count,
             xprt->stat.sends,
             xprt->stat.recvs,
             xprt->stat.bad_xids,
             xprt->stat.req_u,
             xprt->stat.bklog_u,
             xprt->stat.max_slots,
             xprt->stat.sending_u,
             xprt->stat.pending_u);
 }
 
 /**
  * xs_tcp_print_stats - display TCP socket-specific stats
  * @xprt: rpc_xprt struct containing statistics
  * @seq: output file
  *
  */
 static void xs_tcp_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
 {
     struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
     long idle_time = 0;
 
     if (xprt_connected(xprt))
         idle_time = (long)(jiffies - xprt->last_used) / HZ;
 
     seq_printf(seq, "\txprt:\ttcp %u %lu %lu %lu %ld %lu %lu %lu "
             "%llu %llu %lu %llu %llu\n",
             transport->srcport,
             xprt->stat.bind_count,
             xprt->stat.connect_count,
             xprt->stat.connect_time / HZ,
             idle_time,
             xprt->stat.sends,
             xprt->stat.recvs,
             xprt->stat.bad_xids,
             xprt->stat.req_u,
             xprt->stat.bklog_u,
             xprt->stat.max_slots,
             xprt->stat.sending_u,
             xprt->stat.pending_u);
 }
 
 /*
  * Allocate a bunch of pages for a scratch buffer for the rpc code. The reason
  * we allocate pages instead doing a kmalloc like rpc_malloc is because we want
  * to use the server side send routines.
  */
 static int bc_malloc(struct rpc_task *task)
 {
     struct rpc_rqst *rqst = task->tk_rqstp;
     size_t size = rqst->rq_callsize;
     struct page *page;
     struct rpc_buffer *buf;
 
     if (size > PAGE_SIZE - sizeof(struct rpc_buffer)) {
         WARN_ONCE(1, "xprtsock: large bc buffer request (size %zu)\n",
               size);
         return -EINVAL;
     }
 
     page = alloc_page(GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
     if (!page)
         return -ENOMEM;
 
     buf = page_address(page);
     buf->len = PAGE_SIZE;
 
     rqst->rq_buffer = buf->data;
     rqst->rq_rbuffer = (char *)rqst->rq_buffer + rqst->rq_callsize;
     return 0;
 }
 
 /*
  * Free the space allocated in the bc_alloc routine
  */
 static void bc_free(struct rpc_task *task)
 {
     void *buffer = task->tk_rqstp->rq_buffer;
     struct rpc_buffer *buf;
 
     buf = container_of(buffer, struct rpc_buffer, data);
     free_page((unsigned long)buf);
 }
 
 static int bc_sendto(struct rpc_rqst *req)
 {
     struct xdr_buf *xdr = &req->rq_snd_buf;
     struct sock_xprt *transport =
             container_of(req->rq_xprt, struct sock_xprt, xprt);
     struct msghdr msg = {
         .msg_flags  = 0,
     };
     rpc_fraghdr marker = cpu_to_be32(RPC_LAST_STREAM_FRAGMENT |
                      (u32)xdr->len);
     unsigned int sent = 0;
     int err;
 
     req->rq_xtime = ktime_get();
     err = xdr_alloc_bvec(xdr, rpc_task_gfp_mask());
     if (err < 0)
         return err;
     err = xprt_sock_sendmsg(transport->sock, &msg, xdr, 0, marker, &sent);
     xdr_free_bvec(xdr);
     if (err < 0 || sent != (xdr->len + sizeof(marker)))
         return -EAGAIN;
     return sent;
 }
 
 /**
  * bc_send_request - Send a backchannel Call on a TCP socket
  * @req: rpc_rqst containing Call message to be sent
  *
  * xpt_mutex ensures @rqstp's whole message is written to the socket
  * without interruption.
  *
  * Return values:
  *   %0 if the message was sent successfully
  *   %ENOTCONN if the message was not sent
  */
 static int bc_send_request(struct rpc_rqst *req)
 {
     struct svc_xprt *xprt;
     int len;
 
     /*
      * Get the server socket associated with this callback xprt
      */
     xprt = req->rq_xprt->bc_xprt;
 
     /*
      * Grab the mutex to serialize data as the connection is shared
      * with the fore channel
      */
     mutex_lock(&xprt->xpt_mutex);
     if (test_bit(XPT_DEAD, &xprt->xpt_flags))
         len = -ENOTCONN;
     else
         len = bc_sendto(req);
     mutex_unlock(&xprt->xpt_mutex);
 
     if (len > 0)
         len = 0;
 
     return len;
 }
 
 /*
  * The close routine. Since this is client initiated, we do nothing
  */
 
 static void bc_close(struct rpc_xprt *xprt)
 {
     xprt_disconnect_done(xprt);
 }
 
 /*
  * The xprt destroy routine. Again, because this connection is client
  * initiated, we do nothing
  */
 
 static void bc_destroy(struct rpc_xprt *xprt)
 {
     dprintk("RPC:       bc_destroy xprt %p\n", xprt);
 
     xs_xprt_free(xprt);
     module_put(THIS_MODULE);
 }
 
 static const struct rpc_xprt_ops xs_local_ops = {
     .reserve_xprt       = xprt_reserve_xprt,
     .release_xprt       = xprt_release_xprt,
     .alloc_slot     = xprt_alloc_slot,
     .free_slot      = xprt_free_slot,
     .rpcbind        = xs_local_rpcbind,
     .set_port       = xs_local_set_port,
     .connect        = xs_local_connect,
     .buf_alloc      = rpc_malloc,
     .buf_free       = rpc_free,
     .prepare_request    = xs_stream_prepare_request,
     .send_request       = xs_local_send_request,
     .wait_for_reply_request = xprt_wait_for_reply_request_def,
     .close          = xs_close,
     .destroy        = xs_destroy,
     .print_stats        = xs_local_print_stats,
     .enable_swap        = xs_enable_swap,
     .disable_swap       = xs_disable_swap,
 };
 
 static const struct rpc_xprt_ops xs_udp_ops = {
     .set_buffer_size    = xs_udp_set_buffer_size,
     .reserve_xprt       = xprt_reserve_xprt_cong,
     .release_xprt       = xprt_release_xprt_cong,
     .alloc_slot     = xprt_alloc_slot,
     .free_slot      = xprt_free_slot,
     .rpcbind        = rpcb_getport_async,
     .set_port       = xs_set_port,
     .connect        = xs_connect,
     .get_srcaddr        = xs_sock_srcaddr,
     .get_srcport        = xs_sock_srcport,
     .buf_alloc      = rpc_malloc,
     .buf_free       = rpc_free,
     .send_request       = xs_udp_send_request,
     .wait_for_reply_request = xprt_wait_for_reply_request_rtt,
     .timer          = xs_udp_timer,
     .release_request    = xprt_release_rqst_cong,
     .close          = xs_close,
     .destroy        = xs_destroy,
     .print_stats        = xs_udp_print_stats,
     .enable_swap        = xs_enable_swap,
     .disable_swap       = xs_disable_swap,
     .inject_disconnect  = xs_inject_disconnect,
 };
 
 static const struct rpc_xprt_ops xs_tcp_ops = {
     .reserve_xprt       = xprt_reserve_xprt,
     .release_xprt       = xprt_release_xprt,
     .alloc_slot     = xprt_alloc_slot,
     .free_slot      = xprt_free_slot,
     .rpcbind        = rpcb_getport_async,
     .set_port       = xs_set_port,
     .connect        = xs_connect,
     .get_srcaddr        = xs_sock_srcaddr,
     .get_srcport        = xs_sock_srcport,
     .buf_alloc      = rpc_malloc,
     .buf_free       = rpc_free,
     .prepare_request    = xs_stream_prepare_request,
     .send_request       = xs_tcp_send_request,
     .wait_for_reply_request = xprt_wait_for_reply_request_def,
     .close          = xs_tcp_shutdown,
     .destroy        = xs_destroy,
     .set_connect_timeout    = xs_tcp_set_connect_timeout,
     .print_stats        = xs_tcp_print_stats,
     .enable_swap        = xs_enable_swap,
     .disable_swap       = xs_disable_swap,
     .inject_disconnect  = xs_inject_disconnect,
 #ifdef CONFIG_SUNRPC_BACKCHANNEL
     .bc_setup       = xprt_setup_bc,
     .bc_maxpayload      = xs_tcp_bc_maxpayload,
     .bc_num_slots       = xprt_bc_max_slots,
     .bc_free_rqst       = xprt_free_bc_rqst,
     .bc_destroy     = xprt_destroy_bc,
 #endif
 };
 
 /*
  * The rpc_xprt_ops for the server backchannel
  */
 
 static const struct rpc_xprt_ops bc_tcp_ops = {
     .reserve_xprt       = xprt_reserve_xprt,
     .release_xprt       = xprt_release_xprt,
     .alloc_slot     = xprt_alloc_slot,
     .free_slot      = xprt_free_slot,
     .buf_alloc      = bc_malloc,
     .buf_free       = bc_free,
     .send_request       = bc_send_request,
     .wait_for_reply_request = xprt_wait_for_reply_request_def,
     .close          = bc_close,
     .destroy        = bc_destroy,
     .print_stats        = xs_tcp_print_stats,
     .enable_swap        = xs_enable_swap,
     .disable_swap       = xs_disable_swap,
     .inject_disconnect  = xs_inject_disconnect,
 };
 
 static int xs_init_anyaddr(const int family, struct sockaddr *sap)
 {
     static const struct sockaddr_in sin = {
         .sin_family     = AF_INET,
         .sin_addr.s_addr    = htonl(INADDR_ANY),
     };
     static const struct sockaddr_in6 sin6 = {
         .sin6_family        = AF_INET6,
         .sin6_addr      = IN6ADDR_ANY_INIT,
     };
 
     switch (family) {
     case AF_LOCAL:
         break;
     case AF_INET:
         memcpy(sap, &sin, sizeof(sin));
         break;
     case AF_INET6:
         memcpy(sap, &sin6, sizeof(sin6));
         break;
     default:
         dprintk("RPC:       %s: Bad address family\n", __func__);
         return -EAFNOSUPPORT;
     }
     return 0;
 }
 
 static struct rpc_xprt *xs_setup_xprt(struct xprt_create *args,
                       unsigned int slot_table_size,
                       unsigned int max_slot_table_size)
 {
     struct rpc_xprt *xprt;
     struct sock_xprt *new;
 
     if (args->addrlen > sizeof(xprt->addr)) {
         dprintk("RPC:       xs_setup_xprt: address too large\n");
         return ERR_PTR(-EBADF);
     }
 
     xprt = xprt_alloc(args->net, sizeof(*new), slot_table_size,
             max_slot_table_size);
     if (xprt == NULL) {
         dprintk("RPC:       xs_setup_xprt: couldn't allocate "
                 "rpc_xprt\n");
         return ERR_PTR(-ENOMEM);
     }
 
     new = container_of(xprt, struct sock_xprt, xprt);
     mutex_init(&new->recv_mutex);
     memcpy(&xprt->addr, args->dstaddr, args->addrlen);
     xprt->addrlen = args->addrlen;
     if (args->srcaddr)
         memcpy(&new->srcaddr, args->srcaddr, args->addrlen);
     else {
         int err;
         err = xs_init_anyaddr(args->dstaddr->sa_family,
                     (struct sockaddr *)&new->srcaddr);
         if (err != 0) {
             xprt_free(xprt);
             return ERR_PTR(err);
         }
     }
 
     return xprt;
 }
 
 static const struct rpc_timeout xs_local_default_timeout = {
     .to_initval = 10 * HZ,
     .to_maxval = 10 * HZ,
     .to_retries = 2,
 };
 
 /**
  * xs_setup_local - Set up transport to use an AF_LOCAL socket
  * @args: rpc transport creation arguments
  *
  * AF_LOCAL is a "tpi_cots_ord" transport, just like TCP
  */
 static struct rpc_xprt *xs_setup_local(struct xprt_create *args)
 {
     struct sockaddr_un *sun = (struct sockaddr_un *)args->dstaddr;
     struct sock_xprt *transport;
     struct rpc_xprt *xprt;
     struct rpc_xprt *ret;
 
     xprt = xs_setup_xprt(args, xprt_tcp_slot_table_entries,
             xprt_max_tcp_slot_table_entries);
     if (IS_ERR(xprt))
         return xprt;
     transport = container_of(xprt, struct sock_xprt, xprt);
 
     xprt->prot = 0;
     xprt->xprt_class = &xs_local_transport;
     xprt->max_payload = RPC_MAX_FRAGMENT_SIZE;
 
     xprt->bind_timeout = XS_BIND_TO;
     xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
     xprt->idle_timeout = XS_IDLE_DISC_TO;
 
     xprt->ops = &xs_local_ops;
     xprt->timeout = &xs_local_default_timeout;
 
     INIT_WORK(&transport->recv_worker, xs_stream_data_receive_workfn);
     INIT_WORK(&transport->error_worker, xs_error_handle);
     INIT_DELAYED_WORK(&transport->connect_worker, xs_dummy_setup_socket);
 
     switch (sun->sun_family) {
     case AF_LOCAL:
         if (sun->sun_path[0] != '/') {
             dprintk("RPC:       bad AF_LOCAL address: %s\n",
                     sun->sun_path);
             ret = ERR_PTR(-EINVAL);
             goto out_err;
         }
         xprt_set_bound(xprt);
         xs_format_peer_addresses(xprt, "local", RPCBIND_NETID_LOCAL);
         break;
     default:
         ret = ERR_PTR(-EAFNOSUPPORT);
         goto out_err;
     }
 
     dprintk("RPC:       set up xprt to %s via AF_LOCAL\n",
             xprt->address_strings[RPC_DISPLAY_ADDR]);
 
     if (try_module_get(THIS_MODULE))
         return xprt;
     ret = ERR_PTR(-EINVAL);
 out_err:
     xs_xprt_free(xprt);
     return ret;
 }
 
 static const struct rpc_timeout xs_udp_default_timeout = {
     .to_initval = 5 * HZ,
     .to_maxval = 30 * HZ,
     .to_increment = 5 * HZ,
     .to_retries = 5,
 };
 
 /**
  * xs_setup_udp - Set up transport to use a UDP socket
  * @args: rpc transport creation arguments
  *
  */
 static struct rpc_xprt *xs_setup_udp(struct xprt_create *args)
 {
     struct sockaddr *addr = args->dstaddr;
     struct rpc_xprt *xprt;
     struct sock_xprt *transport;
     struct rpc_xprt *ret;
 
     xprt = xs_setup_xprt(args, xprt_udp_slot_table_entries,
             xprt_udp_slot_table_entries);
     if (IS_ERR(xprt))
         return xprt;
     transport = container_of(xprt, struct sock_xprt, xprt);
 
     xprt->prot = IPPROTO_UDP;
     xprt->xprt_class = &xs_udp_transport;
     /* XXX: header size can vary due to auth type, IPv6, etc. */
     xprt->max_payload = (1U << 16) - (MAX_HEADER << 3);
 
     xprt->bind_timeout = XS_BIND_TO;
     xprt->reestablish_timeout = XS_UDP_REEST_TO;
     xprt->idle_timeout = XS_IDLE_DISC_TO;
 
     xprt->ops = &xs_udp_ops;
 
     xprt->timeout = &xs_udp_default_timeout;
 
     INIT_WORK(&transport->recv_worker, xs_udp_data_receive_workfn);
     INIT_WORK(&transport->error_worker, xs_error_handle);
     INIT_DELAYED_WORK(&transport->connect_worker, xs_udp_setup_socket);
 
     switch (addr->sa_family) {
     case AF_INET:
         if (((struct sockaddr_in *)addr)->sin_port != htons(0))
             xprt_set_bound(xprt);
 
         xs_format_peer_addresses(xprt, "udp", RPCBIND_NETID_UDP);
         break;
     case AF_INET6:
         if (((struct sockaddr_in6 *)addr)->sin6_port != htons(0))
             xprt_set_bound(xprt);
 
         xs_format_peer_addresses(xprt, "udp", RPCBIND_NETID_UDP6);
         break;
     default:
         ret = ERR_PTR(-EAFNOSUPPORT);
         goto out_err;
     }
 
     if (xprt_bound(xprt))
         dprintk("RPC:       set up xprt to %s (port %s) via %s\n",
                 xprt->address_strings[RPC_DISPLAY_ADDR],
                 xprt->address_strings[RPC_DISPLAY_PORT],
                 xprt->address_strings[RPC_DISPLAY_PROTO]);
     else
         dprintk("RPC:       set up xprt to %s (autobind) via %s\n",
                 xprt->address_strings[RPC_DISPLAY_ADDR],
                 xprt->address_strings[RPC_DISPLAY_PROTO]);
 
     if (try_module_get(THIS_MODULE))
         return xprt;
     ret = ERR_PTR(-EINVAL);
 out_err:
     xs_xprt_free(xprt);
     return ret;
 }
 
 static const struct rpc_timeout xs_tcp_default_timeout = {
     .to_initval = 60 * HZ,
     .to_maxval = 60 * HZ,
     .to_retries = 2,
 };
 
 /**
  * xs_setup_tcp - Set up transport to use a TCP socket
  * @args: rpc transport creation arguments
  *
  */
 static struct rpc_xprt *xs_setup_tcp(struct xprt_create *args)
 {
     struct sockaddr *addr = args->dstaddr;
     struct rpc_xprt *xprt;
     struct sock_xprt *transport;
     struct rpc_xprt *ret;
     unsigned int max_slot_table_size = xprt_max_tcp_slot_table_entries;
 
     if (args->flags & XPRT_CREATE_INFINITE_SLOTS)
         max_slot_table_size = RPC_MAX_SLOT_TABLE_LIMIT;
 
     xprt = xs_setup_xprt(args, xprt_tcp_slot_table_entries,
             max_slot_table_size);
     if (IS_ERR(xprt))
         return xprt;
     transport = container_of(xprt, struct sock_xprt, xprt);
 
     xprt->prot = IPPROTO_TCP;
     xprt->xprt_class = &xs_tcp_transport;
     xprt->max_payload = RPC_MAX_FRAGMENT_SIZE;
 
     xprt->bind_timeout = XS_BIND_TO;
     xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
     xprt->idle_timeout = XS_IDLE_DISC_TO;
 
     xprt->ops = &xs_tcp_ops;
     xprt->timeout = &xs_tcp_default_timeout;
 
     xprt->max_reconnect_timeout = xprt->timeout->to_maxval;
     xprt->connect_timeout = xprt->timeout->to_initval *
         (xprt->timeout->to_retries + 1);
 
     INIT_WORK(&transport->recv_worker, xs_stream_data_receive_workfn);
     INIT_WORK(&transport->error_worker, xs_error_handle);
     INIT_DELAYED_WORK(&transport->connect_worker, xs_tcp_setup_socket);
 
     switch (addr->sa_family) {
     case AF_INET:
         if (((struct sockaddr_in *)addr)->sin_port != htons(0))
             xprt_set_bound(xprt);
 
         xs_format_peer_addresses(xprt, "tcp", RPCBIND_NETID_TCP);
         break;
     case AF_INET6:
         if (((struct sockaddr_in6 *)addr)->sin6_port != htons(0))
             xprt_set_bound(xprt);
 
         xs_format_peer_addresses(xprt, "tcp", RPCBIND_NETID_TCP6);
         break;
     default:
         ret = ERR_PTR(-EAFNOSUPPORT);
         goto out_err;
     }
 
     if (xprt_bound(xprt))
         dprintk("RPC:       set up xprt to %s (port %s) via %s\n",
                 xprt->address_strings[RPC_DISPLAY_ADDR],
                 xprt->address_strings[RPC_DISPLAY_PORT],
                 xprt->address_strings[RPC_DISPLAY_PROTO]);
     else
         dprintk("RPC:       set up xprt to %s (autobind) via %s\n",
                 xprt->address_strings[RPC_DISPLAY_ADDR],
                 xprt->address_strings[RPC_DISPLAY_PROTO]);
 
     if (try_module_get(THIS_MODULE))
         return xprt;
     ret = ERR_PTR(-EINVAL);
 out_err:
     xs_xprt_free(xprt);
     return ret;
 }
 
 /**
  * xs_setup_bc_tcp - Set up transport to use a TCP backchannel socket
  * @args: rpc transport creation arguments
  *
  */
 static struct rpc_xprt *xs_setup_bc_tcp(struct xprt_create *args)
 {
     struct sockaddr *addr = args->dstaddr;
     struct rpc_xprt *xprt;
     struct sock_xprt *transport;
     struct svc_sock *bc_sock;
     struct rpc_xprt *ret;
 
     xprt = xs_setup_xprt(args, xprt_tcp_slot_table_entries,
             xprt_tcp_slot_table_entries);
     if (IS_ERR(xprt))
         return xprt;
     transport = container_of(xprt, struct sock_xprt, xprt);
 
     xprt->prot = IPPROTO_TCP;
     xprt->xprt_class = &xs_bc_tcp_transport;
     xprt->max_payload = RPC_MAX_FRAGMENT_SIZE;
     xprt->timeout = &xs_tcp_default_timeout;
 
     /* backchannel */
     xprt_set_bound(xprt);
     xprt->bind_timeout = 0;
     xprt->reestablish_timeout = 0;
     xprt->idle_timeout = 0;
 
     xprt->ops = &bc_tcp_ops;
 
     switch (addr->sa_family) {
     case AF_INET:
         xs_format_peer_addresses(xprt, "tcp",
                      RPCBIND_NETID_TCP);
         break;
     case AF_INET6:
         xs_format_peer_addresses(xprt, "tcp",
                    RPCBIND_NETID_TCP6);
         break;
     default:
         ret = ERR_PTR(-EAFNOSUPPORT);
         goto out_err;
     }
 
     dprintk("RPC:       set up xprt to %s (port %s) via %s\n",
             xprt->address_strings[RPC_DISPLAY_ADDR],
             xprt->address_strings[RPC_DISPLAY_PORT],
             xprt->address_strings[RPC_DISPLAY_PROTO]);
 
     /*
      * Once we've associated a backchannel xprt with a connection,
      * we want to keep it around as long as the connection lasts,
      * in case we need to start using it for a backchannel again;
      * this reference won't be dropped until bc_xprt is destroyed.
      */
     xprt_get(xprt);
     args->bc_xprt->xpt_bc_xprt = xprt;
     xprt->bc_xprt = args->bc_xprt;
     bc_sock = container_of(args->bc_xprt, struct svc_sock, sk_xprt);
     transport->sock = bc_sock->sk_sock;
     transport->inet = bc_sock->sk_sk;
 
     /*
      * Since we don't want connections for the backchannel, we set
      * the xprt status to connected
      */
     xprt_set_connected(xprt);
 
     if (try_module_get(THIS_MODULE))
         return xprt;
 
     args->bc_xprt->xpt_bc_xprt = NULL;
     args->bc_xprt->xpt_bc_xps = NULL;
     xprt_put(xprt);
     ret = ERR_PTR(-EINVAL);
 out_err:
     xs_xprt_free(xprt);
     return ret;
 }
 
 static struct xprt_class    xs_local_transport = {
     .list       = LIST_HEAD_INIT(xs_local_transport.list),
     .name       = "named UNIX socket",
     .owner      = THIS_MODULE,
     .ident      = XPRT_TRANSPORT_LOCAL,
     .setup      = xs_setup_local,
     .netid      = { "" },
 };
 
 static struct xprt_class    xs_udp_transport = {
     .list       = LIST_HEAD_INIT(xs_udp_transport.list),
     .name       = "udp",
     .owner      = THIS_MODULE,
     .ident      = XPRT_TRANSPORT_UDP,
     .setup      = xs_setup_udp,
     .netid      = { "udp", "udp6", "" },
 };
 
 static struct xprt_class    xs_tcp_transport = {
     .list       = LIST_HEAD_INIT(xs_tcp_transport.list),
     .name       = "tcp",
     .owner      = THIS_MODULE,
     .ident      = XPRT_TRANSPORT_TCP,
     .setup      = xs_setup_tcp,
     .netid      = { "tcp", "tcp6", "" },
 };
 
 static struct xprt_class    xs_bc_tcp_transport = {
     .list       = LIST_HEAD_INIT(xs_bc_tcp_transport.list),
     .name       = "tcp NFSv4.1 backchannel",
     .owner      = THIS_MODULE,
     .ident      = XPRT_TRANSPORT_BC_TCP,
     .setup      = xs_setup_bc_tcp,
     .netid      = { "" },
 };
 
 /**
  * init_socket_xprt - set up xprtsock's sysctls, register with RPC client
  *
  */
 int init_socket_xprt(void)
 {
     if (!sunrpc_table_header)
         sunrpc_table_header = register_sysctl_table(sunrpc_table);
 
     xprt_register_transport(&xs_local_transport);
     xprt_register_transport(&xs_udp_transport);
     xprt_register_transport(&xs_tcp_transport);
     xprt_register_transport(&xs_bc_tcp_transport);
 
     return 0;
 }
 
 /**
  * cleanup_socket_xprt - remove xprtsock's sysctls, unregister
  *
  */
 void cleanup_socket_xprt(void)
 {
     if (sunrpc_table_header) {
         unregister_sysctl_table(sunrpc_table_header);
         sunrpc_table_header = NULL;
     }
 
     xprt_unregister_transport(&xs_local_transport);
     xprt_unregister_transport(&xs_udp_transport);
     xprt_unregister_transport(&xs_tcp_transport);
     xprt_unregister_transport(&xs_bc_tcp_transport);
 }
 
 static int param_set_portnr(const char *val, const struct kernel_param *kp)
 {
     return param_set_uint_minmax(val, kp,
             RPC_MIN_RESVPORT,
             RPC_MAX_RESVPORT);
 }
 
 static const struct kernel_param_ops param_ops_portnr = {
     .set = param_set_portnr,
     .get = param_get_uint,
 };
 
 #define param_check_portnr(name, p) \
     __param_check(name, p, unsigned int);
 
 module_param_named(min_resvport, xprt_min_resvport, portnr, 0644);
 module_param_named(max_resvport, xprt_max_resvport, portnr, 0644);
 
 static int param_set_slot_table_size(const char *val,
                      const struct kernel_param *kp)
 {
     return param_set_uint_minmax(val, kp,
             RPC_MIN_SLOT_TABLE,
             RPC_MAX_SLOT_TABLE);
 }
 
 static const struct kernel_param_ops param_ops_slot_table_size = {
     .set = param_set_slot_table_size,
     .get = param_get_uint,
 };
 
 #define param_check_slot_table_size(name, p) \
     __param_check(name, p, unsigned int);
 
 static int param_set_max_slot_table_size(const char *val,
                      const struct kernel_param *kp)
 {
     return param_set_uint_minmax(val, kp,
             RPC_MIN_SLOT_TABLE,
             RPC_MAX_SLOT_TABLE_LIMIT);
 }
 
 static const struct kernel_param_ops param_ops_max_slot_table_size = {
     .set = param_set_max_slot_table_size,
     .get = param_get_uint,
 };
 
 #define param_check_max_slot_table_size(name, p) \
     __param_check(name, p, unsigned int);
 
 module_param_named(tcp_slot_table_entries, xprt_tcp_slot_table_entries,
            slot_table_size, 0644);
 module_param_named(tcp_max_slot_table_entries, xprt_max_tcp_slot_table_entries,
            max_slot_table_size, 0644);
 module_param_named(udp_slot_table_entries, xprt_udp_slot_table_entries,
            slot_table_size, 0644);