block: remove legacy IO schedulers

Retain the deadline documentation, as that carries over to mq-deadline
as well.
Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/Kconfig.iosched

@@ -3,67 +3,6 @@ if BLOCK
 
 menu "IO Schedulers"
 
-config IOSCHED_NOOP
-	bool
-	default y
-	---help---
-	  The no-op I/O scheduler is a minimal scheduler that does basic merging
-	  and sorting. Its main uses include non-disk based block devices like
-	  memory devices, and specialised software or hardware environments
-	  that do their own scheduling and require only minimal assistance from
-	  the kernel.
-
-config IOSCHED_DEADLINE
-	tristate "Deadline I/O scheduler"
-	default y
-	---help---
-	  The deadline I/O scheduler is simple and compact. It will provide
-	  CSCAN service with FIFO expiration of requests, switching to
-	  a new point in the service tree and doing a batch of IO from there
-	  in case of expiry.
-
-config IOSCHED_CFQ
-	tristate "CFQ I/O scheduler"
-	default y
-	---help---
-	  The CFQ I/O scheduler tries to distribute bandwidth equally
-	  among all processes in the system. It should provide a fair
-	  and low latency working environment, suitable for both desktop
-	  and server systems.
-
-	  This is the default I/O scheduler.
-
-config CFQ_GROUP_IOSCHED
-	bool "CFQ Group Scheduling support"
-	depends on IOSCHED_CFQ && BLK_CGROUP
-	---help---
-	  Enable group IO scheduling in CFQ.
-
-choice
-
-	prompt "Default I/O scheduler"
-	default DEFAULT_CFQ
-	help
-	  Select the I/O scheduler which will be used by default for all
-	  block devices.
-
-	config DEFAULT_DEADLINE
-		bool "Deadline" if IOSCHED_DEADLINE=y
-
-	config DEFAULT_CFQ
-		bool "CFQ" if IOSCHED_CFQ=y
-
-	config DEFAULT_NOOP
-		bool "No-op"
-
-endchoice
-
-config DEFAULT_IOSCHED
-	string
-	default "deadline" if DEFAULT_DEADLINE
-	default "cfq" if DEFAULT_CFQ
-	default "noop" if DEFAULT_NOOP
-
 config MQ_IOSCHED_DEADLINE
 	tristate "MQ deadline I/O scheduler"
 	default y

block/Makefile

@@ -18,9 +18,6 @@ obj-$(CONFIG_BLK_DEV_BSGLIB)	+= bsg-lib.o
 obj-$(CONFIG_BLK_CGROUP)	+= blk-cgroup.o
 obj-$(CONFIG_BLK_DEV_THROTTLING)	+= blk-throttle.o
 obj-$(CONFIG_BLK_CGROUP_IOLATENCY)	+= blk-iolatency.o
-obj-$(CONFIG_IOSCHED_NOOP)	+= noop-iosched.o
-obj-$(CONFIG_IOSCHED_DEADLINE)	+= deadline-iosched.o
-obj-$(CONFIG_IOSCHED_CFQ)	+= cfq-iosched.o
 obj-$(CONFIG_MQ_IOSCHED_DEADLINE)	+= mq-deadline.o
 obj-$(CONFIG_MQ_IOSCHED_KYBER)	+= kyber-iosched.o
 bfq-y				:= bfq-iosched.o bfq-wf2q.o bfq-cgroup.o

block/elevator.c

@@ -225,8 +225,6 @@ int elevator_init(struct request_queue *q)
 							chosen_elevator);
 	}
 
-	if (!e)
-		e = elevator_get(q, CONFIG_DEFAULT_IOSCHED, false);
 	if (!e) {
 		printk(KERN_ERR
 			"Default I/O scheduler not found. Using noop.\n");
@@ -356,68 +354,6 @@ struct request *elv_rb_find(struct rb_root *root, sector_t sector)
 }
 EXPORT_SYMBOL(elv_rb_find);
 
-/*
- * Insert rq into dispatch queue of q.  Queue lock must be held on
- * entry.  rq is sort instead into the dispatch queue. To be used by
- * specific elevators.
- */
-void elv_dispatch_sort(struct request_queue *q, struct request *rq)
-{
-	sector_t boundary;
-	struct list_head *entry;
-
-	if (q->last_merge == rq)
-		q->last_merge = NULL;
-
-	elv_rqhash_del(q, rq);
-
-	q->nr_sorted--;
-
-	boundary = q->end_sector;
-	list_for_each_prev(entry, &q->queue_head) {
-		struct request *pos = list_entry_rq(entry);
-
-		if (req_op(rq) != req_op(pos))
-			break;
-		if (rq_data_dir(rq) != rq_data_dir(pos))
-			break;
-		if (pos->rq_flags & (RQF_STARTED | RQF_SOFTBARRIER))
-			break;
-		if (blk_rq_pos(rq) >= boundary) {
-			if (blk_rq_pos(pos) < boundary)
-				continue;
-		} else {
-			if (blk_rq_pos(pos) >= boundary)
-				break;
-		}
-		if (blk_rq_pos(rq) >= blk_rq_pos(pos))
-			break;
-	}
-
-	list_add(&rq->queuelist, entry);
-}
-EXPORT_SYMBOL(elv_dispatch_sort);
-
-/*
- * Insert rq into dispatch queue of q.  Queue lock must be held on
- * entry.  rq is added to the back of the dispatch queue. To be used by
- * specific elevators.
- */
-void elv_dispatch_add_tail(struct request_queue *q, struct request *rq)
-{
-	if (q->last_merge == rq)
-		q->last_merge = NULL;
-
-	elv_rqhash_del(q, rq);
-
-	q->nr_sorted--;
-
-	q->end_sector = rq_end_sector(rq);
-	q->boundary_rq = rq;
-	list_add_tail(&rq->queuelist, &q->queue_head);
-}
-EXPORT_SYMBOL(elv_dispatch_add_tail);
-
 enum elv_merge elv_merge(struct request_queue *q, struct request **req,
 		struct bio *bio)
 {
@@ -881,12 +817,6 @@ int elv_register(struct elevator_type *e)
 	list_add_tail(&e->list, &elv_list);
 	spin_unlock(&elv_list_lock);
 
-	/* print pretty message */
-	if (elevator_match(e, chosen_elevator) ||
-			(!*chosen_elevator &&
-			 elevator_match(e, CONFIG_DEFAULT_IOSCHED)))
-				def = " (default)";
-
 	printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name,
 								def);
 	return 0;

block/noop-iosched.c

-/*
- * elevator noop
- */
-#include <linux/blkdev.h>
-#include <linux/elevator.h>
-#include <linux/bio.h>
-#include <linux/module.h>
-#include <linux/slab.h>
-#include <linux/init.h>
-
-struct noop_data {
-	struct list_head queue;
-};
-
-static void noop_merged_requests(struct request_queue *q, struct request *rq,
-				 struct request *next)
-{
-	list_del_init(&next->queuelist);
-}
-
-static int noop_dispatch(struct request_queue *q, int force)
-{
-	struct noop_data *nd = q->elevator->elevator_data;
-	struct request *rq;
-
-	rq = list_first_entry_or_null(&nd->queue, struct request, queuelist);
-	if (rq) {
-		list_del_init(&rq->queuelist);
-		elv_dispatch_sort(q, rq);
-		return 1;
-	}
-	return 0;
-}
-
-static void noop_add_request(struct request_queue *q, struct request *rq)
-{
-	struct noop_data *nd = q->elevator->elevator_data;
-
-	list_add_tail(&rq->queuelist, &nd->queue);
-}
-
-static struct request *
-noop_former_request(struct request_queue *q, struct request *rq)
-{
-	struct noop_data *nd = q->elevator->elevator_data;
-
-	if (rq->queuelist.prev == &nd->queue)
-		return NULL;
-	return list_prev_entry(rq, queuelist);
-}
-
-static struct request *
-noop_latter_request(struct request_queue *q, struct request *rq)
-{
-	struct noop_data *nd = q->elevator->elevator_data;
-
-	if (rq->queuelist.next == &nd->queue)
-		return NULL;
-	return list_next_entry(rq, queuelist);
-}
-
-static int noop_init_queue(struct request_queue *q, struct elevator_type *e)
-{
-	struct noop_data *nd;
-	struct elevator_queue *eq;
-
-	eq = elevator_alloc(q, e);
-	if (!eq)
-		return -ENOMEM;
-
-	nd = kmalloc_node(sizeof(*nd), GFP_KERNEL, q->node);
-	if (!nd) {
-		kobject_put(&eq->kobj);
-		return -ENOMEM;
-	}
-	eq->elevator_data = nd;
-
-	INIT_LIST_HEAD(&nd->queue);
-
-	spin_lock_irq(q->queue_lock);
-	q->elevator = eq;
-	spin_unlock_irq(q->queue_lock);
-	return 0;
-}
-
-static void noop_exit_queue(struct elevator_queue *e)
-{
-	struct noop_data *nd = e->elevator_data;
-
-	BUG_ON(!list_empty(&nd->queue));
-	kfree(nd);
-}
-
-static struct elevator_type elevator_noop = {
-	.ops.sq = {
-		.elevator_merge_req_fn		= noop_merged_requests,
-		.elevator_dispatch_fn		= noop_dispatch,
-		.elevator_add_req_fn		= noop_add_request,
-		.elevator_former_req_fn		= noop_former_request,
-		.elevator_latter_req_fn		= noop_latter_request,
-		.elevator_init_fn		= noop_init_queue,
-		.elevator_exit_fn		= noop_exit_queue,
-	},
-	.elevator_name = "noop",
-	.elevator_owner = THIS_MODULE,
-};
-
-static int __init noop_init(void)
-{
-	return elv_register(&elevator_noop);
-}
-
-static void __exit noop_exit(void)
-{
-	elv_unregister(&elevator_noop);
-}
-
-module_init(noop_init);
-module_exit(noop_exit);
-
-
-MODULE_AUTHOR("Jens Axboe");
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("No-op IO scheduler");