[PATCH] block cleanups: Add kconfig default iosched submenu
Add a kconfig submenu to select the default I/O scheduler, in case
anticipatory is not compiled in or another default is preferred. Also,
since no-op is always available, we should use it whenever the selected
default is not.
Signed-off-by: Nate Diller <nate@namesys.com>
Acked-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/block/Kconfig.iosched b/drivers/block/Kconfig.iosched
index 6070a48..5b90d2f 100644
--- a/drivers/block/Kconfig.iosched
+++ b/drivers/block/Kconfig.iosched
@@ -38,4 +38,32 @@
among all processes in the system. It should provide a fair
working environment, suitable for desktop systems.
+choice
+ prompt "Default I/O scheduler"
+ default DEFAULT_AS
+ help
+ Select the I/O scheduler which will be used by default for all
+ block devices.
+
+ config DEFAULT_AS
+ bool "Anticipatory" if IOSCHED_AS
+
+ config DEFAULT_DEADLINE
+ bool "Deadline" if IOSCHED_DEADLINE
+
+ config DEFAULT_CFQ
+ bool "CFQ" if IOSCHED_CFQ
+
+ config DEFAULT_NOOP
+ bool "No-op"
+
+endchoice
+
+config DEFAULT_IOSCHED
+ string
+ default "anticipatory" if DEFAULT_AS
+ default "deadline" if DEFAULT_DEADLINE
+ default "cfq" if DEFAULT_CFQ
+ default "noop" if DEFAULT_NOOP
+
endmenu
diff --git a/drivers/block/elevator.c b/drivers/block/elevator.c
index 58e881b..3b652eb 100644
--- a/drivers/block/elevator.c
+++ b/drivers/block/elevator.c
@@ -147,24 +147,17 @@
struct elevator_type *e;
/*
- * check if default is set and exists
+ * If default has not been set, use the compiled-in selection.
*/
- if (chosen_elevator[0] && (e = elevator_get(chosen_elevator))) {
- elevator_put(e);
- return;
- }
+ if (!chosen_elevator[0])
+ strcpy(chosen_elevator, CONFIG_DEFAULT_IOSCHED);
-#if defined(CONFIG_IOSCHED_AS)
- strcpy(chosen_elevator, "anticipatory");
-#elif defined(CONFIG_IOSCHED_DEADLINE)
- strcpy(chosen_elevator, "deadline");
-#elif defined(CONFIG_IOSCHED_CFQ)
- strcpy(chosen_elevator, "cfq");
-#elif defined(CONFIG_IOSCHED_NOOP)
- strcpy(chosen_elevator, "noop");
-#else
-#error "You must build at least 1 IO scheduler into the kernel"
-#endif
+ /*
+ * If the given scheduler is not available, fall back to no-op.
+ */
+ if (!(e = elevator_find(chosen_elevator)))
+ strcpy(chosen_elevator, "noop");
+ elevator_put(e);
}
static int __init elevator_setup(char *str)