mount.nfs: Shorter timeout for TCP connects

The standard TCP connect timeout on Linux is 75 seconds, which can be
too long in some cases.  The timeout itself can be altered on a system-wide
basis, but we'd like mount to have it's own connect timeout that's tunable,
and defaults to a shorter value.

The get_socket() function is a utility function that does TCP connects for
getport, clnt_ping, and other functions.  Add logic there to use a
non-blocking connect() and select() in order to time out a connect
operation that's taking too long.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Neil Brown <neilb@suse.de>

diff --git a/utils/mount/network.c b/utils/mount/network.c
index 220bbce0abb57b122e2d2a77f853590e21f31f70..89cb976d0fda0309666853d6a7d3baf510827eea 100644 (file)
--- a/utils/mount/network.c
+++ b/utils/mount/network.c
@@ -52,6 +52,10 @@
 #define NFS_PORT 2049
 #endif
 
+#define PMAP_TIMEOUT   (10)
+#define CONNECT_TIMEOUT        (20)
+#define MOUNT_TIMEOUT  (30)
+
 #if SIZEOF_SOCKLEN_T - 0 == 0
 #define socklen_t unsigned int
 #endif
@@ -157,13 +161,61 @@ int nfs_gethostbyname(const char *hostname, struct sockaddr_in *saddr)
        return 1;
 }
 
+/*
+ * Attempt to connect a socket, but time out after "timeout" seconds.
+ *
+ * On error return, caller closes the socket.
+ */
+static int connect_to(int fd, struct sockaddr *addr,
+                       socklen_t addrlen, int timeout)
+{
+       int ret, saved;
+       fd_set rset, wset;
+       struct timeval tv = {
+               .tv_sec = timeout,
+       };
+
+       saved = fcntl(fd, F_GETFL, 0);
+       fcntl(fd, F_SETFL, saved | O_NONBLOCK);
+
+       ret = connect(fd, addr, addrlen);
+       if (ret < 0 && errno != EINPROGRESS)
+               return -1;
+       if (ret == 0)
+               goto out;
+
+       FD_ZERO(&rset);
+       FD_SET(fd, &rset);
+       wset = rset;
+       ret = select(fd + 1, &rset, &wset, NULL, &tv);
+       if (ret == 0) {
+               errno = ETIMEDOUT;
+               return -1;
+       }
+       if (FD_ISSET(fd, &rset) || FD_ISSET(fd, &wset)) {
+               int error;
+               socklen_t len = sizeof(error);
+               if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &error, &len) < 0)
+                       return -1;
+               if (error) {
+                       errno = error;
+                       return -1;
+               }
+       } else
+               return -1;
+
+out:
+       fcntl(fd, F_SETFL, saved);
+       return 0;
+}
+
 /*
  * Create a socket that is locally bound to a reserved or non-reserved
  * port. For any failures, RPC_ANYSOCK is returned which will cause 
  * the RPC code to create the socket instead. 
  */
 static int get_socket(struct sockaddr_in *saddr, unsigned int p_prot,
-                       int resvp, int conn)
+                       unsigned int timeout, int resvp, int conn)
 {
        int so, cc, type;
        struct sockaddr_in laddr;
@@ -185,7 +237,8 @@ static int get_socket(struct sockaddr_in *saddr, unsigned int p_prot,
                        goto err_bind;
        }
        if (type == SOCK_STREAM || (conn && type == SOCK_DGRAM)) {
-               cc = connect(so, (struct sockaddr *)saddr, namelen);
+               cc = connect_to(so, (struct sockaddr *)saddr, namelen,
+                               timeout);
                if (cc < 0)
                        goto err_connect;
        }
@@ -262,7 +315,7 @@ static unsigned short getport(struct sockaddr_in *saddr,
         * clnt*create() will create one anyway if this
         * fails.
         */
-       socket = get_socket(saddr, proto, FALSE, FALSE);
+       socket = get_socket(saddr, proto, PMAP_TIMEOUT, FALSE, FALSE);
        if (socket == RPC_ANYSOCK) {
                if (proto == IPPROTO_TCP && errno == ETIMEDOUT) {
                        /*
@@ -552,7 +605,8 @@ CLIENT *mnt_openclnt(clnt_addr_t *mnt_server, int *msock)
        CLIENT *clnt = NULL;
 
        mnt_saddr->sin_port = htons((u_short)mnt_pmap->pm_port);
-       *msock = get_socket(mnt_saddr, mnt_pmap->pm_prot, TRUE, FALSE);
+       *msock = get_socket(mnt_saddr, mnt_pmap->pm_prot, MOUNT_TIMEOUT,
+                               TRUE, FALSE);
        if (*msock == RPC_ANYSOCK) {
                if (rpc_createerr.cf_error.re_errno == EADDRINUSE)
                        /*
@@ -608,7 +662,7 @@ int clnt_ping(struct sockaddr_in *saddr, const unsigned long prog,
        struct sockaddr dissolve;
 
        rpc_createerr.cf_stat = stat = errno = 0;
-       sock = get_socket(saddr, prot, FALSE, TRUE);
+       sock = get_socket(saddr, prot, CONNECT_TIMEOUT, FALSE, TRUE);
        if (sock == RPC_ANYSOCK) {
                if (errno == ETIMEDOUT) {
                        /*