From 94b98430cb83a8f4e62d837100fc357e9eb12ca6 Mon Sep 17 00:00:00 2001
From: Kenneth Lakin <kennethlakin@gmail.com>
Date: Tue, 3 Nov 2015 03:33:06 -0800
Subject: [PATCH] start-stop-daemon: Add SSD_IONICELEVEL

This is the disk IO counterpart to SSD_NICELEVEL.
Modified by William Hubbs to add the variable to the start-stop-daemon
man page.

This fixes #69.
---
 etc/rc.conf                |  3 +++
 man/start-stop-daemon.8    |  4 ++++
 src/rc/start-stop-daemon.c | 14 +++++++++++++-
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/etc/rc.conf b/etc/rc.conf
index 80f68ddf..cbb660a6 100644
--- a/etc/rc.conf
+++ b/etc/rc.conf
@@ -117,6 +117,9 @@
 # Some daemons are started and stopped via start-stop-daemon.
 # We can set some things on a per service basis, like the nicelevel.
 #SSD_NICELEVEL="-19"
+# Or the ionice level. The format is class[:data] , just like the
+# --ionice start-stop-daemon parameter.
+#SSD_IONICELEVEL="2:2"
 
 # Pass ulimit parameters
 # If you are using bash in POSIX mode for your shell, note that the
diff --git a/man/start-stop-daemon.8 b/man/start-stop-daemon.8
index c3288955..112cd5fb 100644
--- a/man/start-stop-daemon.8
+++ b/man/start-stop-daemon.8
@@ -153,6 +153,10 @@ The retry specification can be either a timeout in seconds or multiple
 signal/timeout pairs (like SIGTERM/5).
 .El
 .Sh ENVIRONMENT
+.Va SSD_IONICELEVEL
+can also set the IO scheduling priority of the daemon, but the command line
+option takes precedence.
+.Pp
 .Va SSD_NICELEVEL
 can also set the scheduling priority of the daemon, but the command line
 option takes precedence.
diff --git a/src/rc/start-stop-daemon.c b/src/rc/start-stop-daemon.c
index 27939c2c..188169fd 100644
--- a/src/rc/start-stop-daemon.c
+++ b/src/rc/start-stop-daemon.c
@@ -696,6 +696,17 @@ int main(int argc, char **argv)
 		if (sscanf(tmp, "%d", &nicelevel) != 1)
 			eerror("%s: invalid nice level `%s' (SSD_NICELEVEL)",
 			    applet, tmp);
+		if ((tmp = getenv("SSD_IONICELEVEL"))) {
+			int n = sscanf(tmp, "%d:%d", &ionicec, &ioniced);
+			if (n != 1 && n != 2)
+				eerror("%s: invalid ionice level `%s' (SSD_IONICELEVEL)",
+				    applet, tmp);
+			if (ionicec == 0)
+				ioniced = 0;
+			else if (ionicec == 3)
+				ioniced = 7;
+			ionicec <<= 13; /* class shift */
+		}
 
 	/* Get our user name and initial dir */
 	p = getenv("USER");
@@ -1195,7 +1206,8 @@ int main(int argc, char **argv)
 			if ((strncmp(env->value, "RC_", 3) == 0 &&
 				strncmp(env->value, "RC_SERVICE=", 10) != 0 &&
 				strncmp(env->value, "RC_SVCNAME=", 10) != 0) ||
-			    strncmp(env->value, "SSD_NICELEVEL=", 14) == 0)
+				strncmp(env->value, "SSD_NICELEVEL=", 14) == 0 ||
+				strncmp(env->value, "SSD_IONICELEVEL=", 16) == 0)
 			{
 				p = strchr(env->value, '=');
 				*p = '\0';