init, block: try to load default elevator module early during boot
This patch adds default module loading and uses it to load the default
block elevator. During boot, it's called right after initramfs or
initrd is made available and right before control is passed to
userland. This ensures that as long as the modules are available in
the usual places in initramfs, initrd or the root filesystem, the
default modules are loaded as soon as possible.
This will replace the on-demand elevator module loading from elevator
init path.
v2: Fixed build breakage when !CONFIG_BLOCK. Reported by kbuild test
robot.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alex Riesen <raa.lkml@gmail.com>
Cc: Fengguang We <fengguang.wu@intel.com>
diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index 5e4ded5..dfe606a 100644
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -57,6 +57,9 @@
sys_mkdir("/old", 0700);
sys_chdir("/old");
+ /* try loading default modules from initrd */
+ load_default_modules();
+
/*
* In case that a resume from disk is carried out by linuxrc or one of
* its children, we need to tell the freezer not to wait for us.
diff --git a/init/initramfs.c b/init/initramfs.c
index 84c6bf1..a67ef9d 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -592,7 +592,7 @@
initrd_end - initrd_start);
if (!err) {
free_initrd();
- return 0;
+ goto done;
} else {
clean_rootfs();
unpack_to_rootfs(__initramfs_start, __initramfs_size);
@@ -607,6 +607,7 @@
sys_close(fd);
free_initrd();
}
+ done:
#else
printk(KERN_INFO "Unpacking initramfs...\n");
err = unpack_to_rootfs((char *)initrd_start,
@@ -615,6 +616,11 @@
printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
free_initrd();
#endif
+ /*
+ * Try loading default modules from initramfs. This gives
+ * us a chance to load before device_initcalls.
+ */
+ load_default_modules();
}
return 0;
}
diff --git a/init/main.c b/init/main.c
index baf1f0f..18efadb 100644
--- a/init/main.c
+++ b/init/main.c
@@ -70,6 +70,8 @@
#include <linux/perf_event.h>
#include <linux/file.h>
#include <linux/ptrace.h>
+#include <linux/blkdev.h>
+#include <linux/elevator.h>
#include <asm/io.h>
#include <asm/bugs.h>
@@ -794,6 +796,17 @@
do_one_initcall(*fn);
}
+/*
+ * This function requests modules which should be loaded by default and is
+ * called twice right after initrd is mounted and right before init is
+ * exec'd. If such modules are on either initrd or rootfs, they will be
+ * loaded before control is passed to userland.
+ */
+void __init load_default_modules(void)
+{
+ load_default_elevator_module();
+}
+
static int run_init_process(const char *init_filename)
{
argv_init[0] = init_filename;
@@ -898,4 +911,7 @@
* we're essentially up and running. Get rid of the
* initmem segments and start the user-mode stuff..
*/
+
+ /* rootfs is available now, try loading default modules */
+ load_default_modules();
}