block: remove dead elevator code

This removes a bunch of core and elevator related code. On the core
front, we remove anything related to queue running, draining,
initialization, plugging, and congestions. We also kill anything
related to request allocation, merging, retrieval, and completion.

Remove any checking for single queue IO schedulers, as they no
longer exist. This means we can also delete a bunch of code related
to request issue, adding, completion, etc - and all the SQ related
ops and helpers.

Also kill the load_default_modules(), as all that did was provide
for a way to load the default single queue elevator.

Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 0 insertions, 21 deletions

diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index d1a5d885ce13..73e02ea5d5d1 100644
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -53,9 +53,6 @@ static void __init handle_initrd(void)
         ksys_mkdir("/old", 0700);
         ksys_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 640557788026..96af18fec4d0 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -644,12 +644,6 @@ static int __init populate_rootfs(void)
 #endif
         }
         flush_delayed_fput();
-        /*
-         * Try loading default modules from initramfs.  This gives
-         * us a chance to load before device_initcalls.
-         */
-        load_default_modules();
-
         return 0;
 }
 rootfs_initcall(populate_rootfs);
diff --git a/init/main.c b/init/main.c
index ee147103ba1b..ca0cdb0c388b 100644
--- a/init/main.c
+++ b/init/main.c
@@ -996,17 +996,6 @@ static void __init do_pre_smp_initcalls(void)
                 do_one_initcall(initcall_from_entry(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;
@@ -1180,5 +1169,4 @@ static noinline void __init kernel_init_freeable(void)
          */
 
         integrity_load_keys();
-        load_default_modules();
 }