Bug#695281: Please apply attached patch that optionally disables calling sync() in runit(8)

[Andras Korn]

Package: runit
Version: 2.1.1-6.2
Severity: wishlist
Tags: patch

Hi,

I use runit extensively in vservers. Restarting a vserver occasionally takes
a lot longer than necessary because runit(8) insists on calling sync()
before shutting down. This is desirable on physical hosts, of course, but
not in a vserver (which is basically just a glorified chroot).

I wrote a small patch that adds a /etc/runit/nosync flag file that, if it
exists, inhibits calling sync() on reboot/shutdown.

Please consider applying it.

Thanks

Andras

-- 
                     Andras Korn <korn at elan.rulez.org>
            There is an answer to every question. Usually it's No.

diff -ru runit-2.1.1/doc/runit.8.html runit-2.1.1+nosync/doc/runit.8.html
--- runit-2.1.1/doc/runit.8.html	2009-10-04 22:44:02.000000000 +0200
+++ runit-2.1.1+nosync/doc/runit.8.html	2012-12-06 16:48:51.239082000 +0100
@@ -34,6 +34,8 @@
 and possibly halt or reboot the system are done here. If stage 3 returns,
 <b>runit</b> checks if the file <i>/etc/runit/reboot</i> exists and has the execute by
 owner permission set. If so, the system is rebooted, it&rsquo;s halted otherwise.
+If <i>/etc/runit/nosync</i> exists, <b>runit</b> doesn&rsquo;t invoke
+sync(). This is useful in vservers.
 
 <h2><a name='sect6'>Ctrl-alt-del</a></h2>
 If <b>runit</b> receives the ctrl-alt-del keyboard request and the file
diff -ru runit-2.1.1/man/runit.8 runit-2.1.1+nosync/man/runit.8
--- runit-2.1.1/man/runit.8	2009-10-04 22:44:02.000000000 +0200
+++ runit-2.1.1+nosync/man/runit.8	2012-12-06 16:48:52.392406000 +0100
@@ -48,6 +48,11 @@
 .I /etc/runit/reboot
 exists and has the execute by owner permission set.
 If so, the system is rebooted, it's halted otherwise.
+If
+.I /etc/runit/nosync
+exists,
+.B runit
+doesn't invoke sync(). This is useful in vservers.
 .SH CTRL-ALT-DEL
 If
 .B runit
diff -ru runit-2.1.1/src/runit.c runit-2.1.1+nosync/src/runit.c
--- runit-2.1.1/src/runit.c	2009-10-04 22:44:02.000000000 +0200
+++ runit-2.1.1+nosync/src/runit.c	2012-12-06 16:44:30.055219000 +0100
@@ -41,6 +41,11 @@
 }
 void sig_child_handler (void) { write(selfpipe[1], "", 1); }
 
+void sync_if_needed() {
+  struct stat s;
+  if (stat(NOSYNC, &s) == -1) sync();
+}
+
 int main (int argc, const char * const *argv, char * const *envp) {
   const char * prog[2];
   int pid, pid2;
@@ -305,28 +310,28 @@
   case -1:
   if ((stat(REBOOT, &s) != -1) && (s.st_mode & S_IXUSR)) {
     strerr_warn2(INFO, "system reboot.", 0);
-    sync();
+    sync_if_needed();
     reboot_system(RB_AUTOBOOT);
   }
   else {
 #ifdef RB_POWER_OFF
     strerr_warn2(INFO, "power off...", 0);
-    sync();
+    sync_if_needed();
     reboot_system(RB_POWER_OFF);
     sleep(2);
 #endif
 #ifdef RB_HALT_SYSTEM
     strerr_warn2(INFO, "system halt.", 0);
-    sync();
+    sync_if_needed();
     reboot_system(RB_HALT_SYSTEM);
 #else
 #ifdef RB_HALT
     strerr_warn2(INFO, "system halt.", 0);
-    sync();
+    sync_if_needed();
     reboot_system(RB_HALT);
 #else
     strerr_warn2(INFO, "system reboot.", 0);
-    sync();
+    sync_if_needed();
     reboot_system(RB_AUTOBOOT);
 #endif
 #endif
diff -ru runit-2.1.1/src/runit.h runit-2.1.1+nosync/src/runit.h
--- runit-2.1.1/src/runit.h	2009-10-04 22:44:02.000000000 +0200
+++ runit-2.1.1+nosync/src/runit.h	2012-12-06 16:39:28.781315000 +0100
@@ -1,4 +1,5 @@
 #define RUNIT "/sbin/runit"
 #define STOPIT "/etc/runit/stopit"
 #define REBOOT "/etc/runit/reboot"
+#define NOSYNC "/erc/runit/nosync"
 #define CTRLALTDEL "/etc/runit/ctrlaltdel"