multiple threads for mountd

[nfs-utils.git] / utils / mountd / mountd.c

diff --git a/utils/mountd/mountd.c b/utils/mountd/mountd.c
index 43606dd39350c6e50abdb8206c5ace4a6d1e657f..e402bf822d18849739396d5a091b5f62dee9f19f 100644 (file)
--- a/utils/mountd/mountd.c
+++ b/utils/mountd/mountd.c
@@ -21,6 +21,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/resource.h>
+#include <sys/wait.h>
 #include "xmalloc.h"
 #include "misc.h"
 #include "mountd.h"
@@ -43,6 +44,13 @@ int new_cache = 0;
  * send mount or unmount requests -- the callout is not needed for 2.6 kernel */
 char *ha_callout_prog = NULL;
 
+/* Number of mountd threads to start.   Default is 1 and
+ * that's probably enough unless you need hundreds of
+ * clients to be able to mount at once.  */
+static int num_threads = 1;
+/* Arbitrary limit on number of threads */
+#define MAX_THREADS 64
+
 static struct option longopts[] =
 {
        { "foreground", 0, 0, 'F' },
@@ -57,24 +65,106 @@ static struct option longopts[] =
        { "no-tcp", 0, 0, 'n' },
        { "ha-callout", 1, 0, 'H' },
        { "state-directory-path", 1, 0, 's' },
+       { "num-threads", 1, 0, 't' },
        { NULL, 0, 0, 0 }
 };
 
 static int nfs_version = -1;
 
+static void
+unregister_services (void)
+{
+       if (nfs_version & 0x1)
+               pmap_unset (MOUNTPROG, MOUNTVERS);
+       if (nfs_version & (0x1 << 1))
+               pmap_unset (MOUNTPROG, MOUNTVERS_POSIX);
+       if (nfs_version & (0x1 << 2))
+               pmap_unset (MOUNTPROG, MOUNTVERS_NFSV3);
+}
+
+/* Wait for all worker child processes to exit and reap them */
+static void
+wait_for_workers (void)
+{
+       int status;
+       pid_t pid;
+
+       for (;;) {
+
+               pid = waitpid(0, &status, 0);
+
+               if (pid < 0) {
+                       if (errno == ECHILD)
+                               return; /* no more children */
+                       xlog(L_FATAL, "mountd: can't wait: %s\n",
+                                       strerror(errno));
+               }
+
+               /* Note: because we SIG_IGN'd SIGCHLD earlier, this
+                * does not happen on 2.6 kernels, and waitpid() blocks
+                * until all the children are dead then returns with
+                * -ECHILD.  But, we don't need to do anything on the
+                * death of individual workers, so we don't care. */
+               xlog(L_NOTICE, "mountd: reaped child %d, status %d\n",
+                               (int)pid, status);
+       }
+}
+
+/* Fork num_threads worker children and wait for them */
+static void
+fork_workers(void)
+{
+       int i;
+       pid_t pid;
+
+       xlog(L_NOTICE, "mountd: starting %d threads\n", num_threads);
+
+       for (i = 0 ; i < num_threads ; i++) {
+               pid = fork();
+               if (pid < 0) {
+                       xlog(L_FATAL, "mountd: cannot fork: %s\n",
+                                       strerror(errno));
+               }
+               if (pid == 0) {
+                       /* worker child */
+
+                       /* Re-enable the default action on SIGTERM et al
+                        * so that workers die naturally when sent them.
+                        * Only the parent unregisters with pmap and
+                        * hence needs to do special SIGTERM handling. */
+                       struct sigaction sa;
+                       sa.sa_handler = SIG_DFL;
+                       sa.sa_flags = 0;
+                       sigemptyset(&sa.sa_mask);
+                       sigaction(SIGHUP, &sa, NULL);
+                       sigaction(SIGINT, &sa, NULL);
+                       sigaction(SIGTERM, &sa, NULL);
+
+                       /* fall into my_svc_run in caller */
+                       return;
+               }
+       }
+
+       /* in parent */
+       wait_for_workers();
+       unregister_services();
+       xlog(L_NOTICE, "mountd: no more workers, exiting\n");
+       exit(0);
+}
+
 /*
  * Signal handler.
  */
 static void 
 killer (int sig)
 {
-  if (nfs_version & 0x1)
-    pmap_unset (MOUNTPROG, MOUNTVERS);
-  if (nfs_version & (0x1 << 1))
-    pmap_unset (MOUNTPROG, MOUNTVERS_POSIX);
-  if (nfs_version & (0x1 << 2))
-    pmap_unset (MOUNTPROG, MOUNTVERS_NFSV3);
-  xlog (L_FATAL, "Caught signal %d, un-registering and exiting.", sig);
+       unregister_services();
+       if (num_threads > 1) {
+               /* play Kronos and eat our children */
+               kill(0, SIGTERM);
+               wait_for_workers();
+       }
+       xlog (L_FATAL, "Caught signal %d, un-registering and exiting.", sig);
 }
 
 static void
@@ -468,7 +558,7 @@ main(int argc, char **argv)
 
        /* Parse the command line options and arguments. */
        opterr = 0;
-       while ((c = getopt_long(argc, argv, "o:n:Fd:f:p:P:hH:N:V:vs:", longopts, NULL)) != EOF)
+       while ((c = getopt_long(argc, argv, "o:n:Fd:f:p:P:hH:N:V:vs:t:", longopts, NULL)) != EOF)
                switch (c) {
                case 'o':
                        descriptors = atoi(optarg);
@@ -515,6 +605,9 @@ main(int argc, char **argv)
                                exit(1);
                        }
                        break;
+               case 't':
+                       num_threads = atoi (optarg);
+                       break;
                case 'V':
                        nfs_version |= 1 << (atoi (optarg) - 1);
                        break;
@@ -615,6 +708,17 @@ main(int argc, char **argv)
                setsid();
        }
 
+       /* silently bounds check num_threads */
+       if (foreground)
+               num_threads = 1;
+       else if (num_threads < 1)
+               num_threads = 1;
+       else if (num_threads > MAX_THREADS)
+               num_threads = MAX_THREADS;
+
+       if (num_threads > 1)
+               fork_workers();
+
        my_svc_run();
 
        xlog(L_ERROR, "Ack! Gack! svc_run returned!\n");
@@ -629,6 +733,7 @@ usage(const char *prog, int n)
 "      [-o num|--descriptors num] [-f exports-file|--exports-file=file]\n"
 "      [-p|--port port] [-V version|--nfs-version version]\n"
 "      [-N version|--no-nfs-version version] [-n|--no-tcp]\n"
-"      [-H ha-callout-prog] [-s|--state-directory-path path]\n", prog);
+"      [-H ha-callout-prog] [-s|--state-directory-path path]\n"
+"      [-t num|--num-threads=num]\n", prog);
        exit(n);
 }