From 57371e5829a61e5ee6c9f98404dfc729d6c62608 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Wed, 5 Sep 2012 15:32:57 -0700
Subject: [PATCH] shutdown: remove explicit sync() invocations

The kernel implicitly does sync() anyway, hence there is no need to do
that in userspace explicitly. This makes the "-n" switch to halt(8) a
noop.
---
 man/halt.xml              |  9 ---------
 src/core/shutdown.c       |  2 --
 src/systemctl/systemctl.c | 11 +----------
 3 files changed, 1 insertion(+), 21 deletions(-)

diff --git a/man/halt.xml b/man/halt.xml
index 7ba85ed88..ed1c52c58 100644
--- a/man/halt.xml
+++ b/man/halt.xml
@@ -135,15 +135,6 @@
                                 shutdown entry.</para></listitem>
                         </varlistentry>
 
-                        <varlistentry>
-                                <term><option>-n</option></term>
-                                <term><option>--no-sync</option></term>
-
-                                <listitem><para>Don't sync hard disks/storage media before
-                                halt, power-off,
-                                reboot.</para></listitem>
-                        </varlistentry>
-
                         <varlistentry>
                                 <term><option>--no-wall</option></term>
 
diff --git a/src/core/shutdown.c b/src/core/shutdown.c
index c3a4c390b..558111b3d 100644
--- a/src/core/shutdown.c
+++ b/src/core/shutdown.c
@@ -279,8 +279,6 @@ int main(int argc, char *argv[]) {
                 }
         }
 
-        sync();
-
         if (cmd == LINUX_REBOOT_CMD_KEXEC) {
                 /* We cheat and exec kexec to avoid doing all its work */
                 pid_t pid = fork();
diff --git a/src/systemctl/systemctl.c b/src/systemctl/systemctl.c
index 871a04bc1..14f8a129d 100644
--- a/src/systemctl/systemctl.c
+++ b/src/systemctl/systemctl.c
@@ -74,7 +74,6 @@ static bool arg_no_block = false;
 static bool arg_no_legend = false;
 static bool arg_no_pager = false;
 static bool arg_no_wtmp = false;
-static bool arg_no_sync = false;
 static bool arg_no_wall = false;
 static bool arg_no_reload = false;
 static bool arg_dry = false;
@@ -3949,7 +3948,6 @@ static int halt_help(void) {
                "  -f --force     Force immediate halt/power-off/reboot\n"
                "  -w --wtmp-only Don't halt/power-off/reboot, just write wtmp record\n"
                "  -d --no-wtmp   Don't write wtmp record\n"
-               "  -n --no-sync   Don't sync before halt/power-off/reboot\n"
                "     --no-wall   Don't send wall message before halt/power-off/reboot\n",
                program_invocation_short_name,
                arg_action == ACTION_REBOOT   ? "Reboot" :
@@ -4271,7 +4269,6 @@ static int halt_parse_argv(int argc, char *argv[]) {
                 { "force",     no_argument,       NULL, 'f'         },
                 { "wtmp-only", no_argument,       NULL, 'w'         },
                 { "no-wtmp",   no_argument,       NULL, 'd'         },
-                { "no-sync",   no_argument,       NULL, 'n'         },
                 { "no-wall",   no_argument,       NULL, ARG_NO_WALL },
                 { NULL,        0,                 NULL, 0           }
         };
@@ -4317,16 +4314,13 @@ static int halt_parse_argv(int argc, char *argv[]) {
                         arg_no_wtmp = true;
                         break;
 
-                case 'n':
-                        arg_no_sync = true;
-                        break;
-
                 case ARG_NO_WALL:
                         arg_no_wall = true;
                         break;
 
                 case 'i':
                 case 'h':
+                case 'n':
                         /* Compatibility nops */
                         break;
 
@@ -5168,9 +5162,6 @@ static int halt_main(DBusConnection *bus) {
                 }
         }
 
-        if (!arg_no_sync)
-                sync();
-
         if (arg_dry)
                 return 0;
 
-- 
2.30.2