[PATCH] raid: make RAID autodetect default a KConfig option

Arjan van de Ven
2008-09-21T22:45:49Z

>From 812bf9a448d96375a3aec5c51764d74cace85abb Mon Sep 17 00:00:00 2001
From: Arjan van de Ven <arjan@linux.intel.com>
Date: Sun, 21 Sep 2008 15:44:32 -0700
Subject: [PATCH] raid: make RAID autodetect default a KConfig option

RAID autodetect has the side effect of requiring synchronisation
of all device drivers, which can make the boot several seconds longer
(I've measured 7 on one of my laptops).... even for systems that don't
have RAID setup for the root filesystem (the only FS where this matters).

This patch makes the default for autodetect a config option; either way
the user can always override via the kernel command line.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
---
drivers/md/Kconfig | 14 ++++++++++++++
init/do_mounts_md.c | 11 +++++++++--
2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 07d92c1..8e72c91 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -30,6 +30,20 @@ config BLK_DEV_MD

If unsure, say N.

+config MD_AUTODETECT
+ bool "Autodetect RAID arrays during kernel boot"
+ depends on BLK_DEV_MD
+ default y
+ ---help---
+ If you say Y here, then the kernel will try to autodetect raid
+ arrays as part of its boot process.
+
+ If you don't use raid and say Y, this autodetection can cause
+ a several-second delay in the boot time due to various
+ synchronisation steps that are part of this step.
+
+ If unsure, say Y.
+
config MD_LINEAR
tristate "Linear (append) mode"
depends on BLK_DEV_MD
diff --git a/init/do_mounts_md.c b/init/do_mounts_md.c
index c0dfd3c..48b3fad 100644
--- a/init/do_mounts_md.c
+++ b/init/do_mounts_md.c
@@ -12,7 +12,12 @@
* The code for that is here.
*/

-static int __initdata raid_noautodetect, raid_autopart;
+#ifdef CONFIG_MD_AUTODETECT
+static int __initdata raid_noautodetect;
+#else
+static int __initdata raid_noautodetect=1;
+#endif
+static int __initdata raid_autopart;

static struct {
int minor;
@@ -252,6 +257,8 @@ static int __init raid_setup(char *str)

if (!strncmp(str, "noautodetect", wlen))
raid_noautodetect = 1;
+ if (!strncmp(str, "autodetect", wlen))
+ raid_noautodetect = 0;
if (strncmp(str, "partitionable", wlen)==0)
raid_autopart = 1;
if (strncmp(str, "part", wlen)==0)
@@ -288,7 +295,7 @@ void __init md_run_setup(void)
create_dev("/dev/md0", MKDEV(MD_MAJOR, 0));

if (raid_noautodetect)
- printk(KERN_INFO "md: Skipping autodetection of RAID arrays. (raid=noautodetect)\n");
+ printk(KERN_INFO "md: Skipping autodetection of RAID arrays. (raid=autodetect will force)\n");
else
autodetect_raid();
md_setup_drive();
--
1.5.5.1

--
Arjan van de Ven Intel Open Source Technology Centre
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