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>

1 files changed, 0 insertions, 560 deletions

diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
deleted file mode 100644
index ef2f1f09e9b3..000000000000
--- a/block/deadline-iosched.c
+++ /dev/null
@@ -1,560 +0,0 @@
-/*
- *  Deadline i/o scheduler.
- *
- *  Copyright (C) 2002 Jens Axboe <axboe@kernel.dk>
- */
-#include <linux/kernel.h>
-#include <linux/fs.h>
-#include <linux/blkdev.h>
-#include <linux/elevator.h>
-#include <linux/bio.h>
-#include <linux/module.h>
-#include <linux/slab.h>
-#include <linux/init.h>
-#include <linux/compiler.h>
-#include <linux/rbtree.h>
-
-/*
- * See Documentation/block/deadline-iosched.txt
- */
-static const int read_expire = HZ / 2;  /* max time before a read is submitted. */
-static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
-static const int writes_starved = 2;    /* max times reads can starve a write */
-static const int fifo_batch = 16;       /* # of sequential requests treated as one
-				     by the above parameters. For throughput. */
-
-struct deadline_data {
-	/*
-	 * run time data
-	 */
-
-	/*
-	 * requests (deadline_rq s) are present on both sort_list and fifo_list
-	 */
-	struct rb_root sort_list[2];	
-	struct list_head fifo_list[2];
-
-	/*
-	 * next in sort order. read, write or both are NULL
-	 */
-	struct request *next_rq[2];
-	unsigned int batching;		/* number of sequential requests made */
-	unsigned int starved;		/* times reads have starved writes */
-
-	/*
-	 * settings that change how the i/o scheduler behaves
-	 */
-	int fifo_expire[2];
-	int fifo_batch;
-	int writes_starved;
-	int front_merges;
-};
-
-static inline struct rb_root *
-deadline_rb_root(struct deadline_data *dd, struct request *rq)
-{
-	return &dd->sort_list[rq_data_dir(rq)];
-}
-
-/*
- * get the request after `rq' in sector-sorted order
- */
-static inline struct request *
-deadline_latter_request(struct request *rq)
-{
-	struct rb_node *node = rb_next(&rq->rb_node);
-
-	if (node)
-		return rb_entry_rq(node);
-
-	return NULL;
-}
-
-static void
-deadline_add_rq_rb(struct deadline_data *dd, struct request *rq)
-{
-	struct rb_root *root = deadline_rb_root(dd, rq);
-
-	elv_rb_add(root, rq);
-}
-
-static inline void
-deadline_del_rq_rb(struct deadline_data *dd, struct request *rq)
-{
-	const int data_dir = rq_data_dir(rq);
-
-	if (dd->next_rq[data_dir] == rq)
-		dd->next_rq[data_dir] = deadline_latter_request(rq);
-
-	elv_rb_del(deadline_rb_root(dd, rq), rq);
-}
-
-/*
- * add rq to rbtree and fifo
- */
-static void
-deadline_add_request(struct request_queue *q, struct request *rq)
-{
-	struct deadline_data *dd = q->elevator->elevator_data;
-	const int data_dir = rq_data_dir(rq);
-
-	/*
-	 * This may be a requeue of a write request that has locked its
-	 * target zone. If it is the case, this releases the zone lock.
-	 */
-	blk_req_zone_write_unlock(rq);
-
-	deadline_add_rq_rb(dd, rq);
-
-	/*
-	 * set expire time and add to fifo list
-	 */
-	rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
-	list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]);
-}
-
-/*
- * remove rq from rbtree and fifo.
- */
-static void deadline_remove_request(struct request_queue *q, struct request *rq)
-{
-	struct deadline_data *dd = q->elevator->elevator_data;
-
-	rq_fifo_clear(rq);
-	deadline_del_rq_rb(dd, rq);
-}
-
-static enum elv_merge
-deadline_merge(struct request_queue *q, struct request **req, struct bio *bio)
-{
-	struct deadline_data *dd = q->elevator->elevator_data;
-	struct request *__rq;
-
-	/*
-	 * check for front merge
-	 */
-	if (dd->front_merges) {
-		sector_t sector = bio_end_sector(bio);
-
-		__rq = elv_rb_find(&dd->sort_list[bio_data_dir(bio)], sector);
-		if (__rq) {
-			BUG_ON(sector != blk_rq_pos(__rq));
-
-			if (elv_bio_merge_ok(__rq, bio)) {
-				*req = __rq;
-				return ELEVATOR_FRONT_MERGE;
-			}
-		}
-	}
-
-	return ELEVATOR_NO_MERGE;
-}
-
-static void deadline_merged_request(struct request_queue *q,
-				    struct request *req, enum elv_merge type)
-{
-	struct deadline_data *dd = q->elevator->elevator_data;
-
-	/*
-	 * if the merge was a front merge, we need to reposition request
-	 */
-	if (type == ELEVATOR_FRONT_MERGE) {
-		elv_rb_del(deadline_rb_root(dd, req), req);
-		deadline_add_rq_rb(dd, req);
-	}
-}
-
-static void
-deadline_merged_requests(struct request_queue *q, struct request *req,
-			 struct request *next)
-{
-	/*
-	 * if next expires before rq, assign its expire time to rq
-	 * and move into next position (next will be deleted) in fifo
-	 */
-	if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
-		if (time_before((unsigned long)next->fifo_time,
-				(unsigned long)req->fifo_time)) {
-			list_move(&req->queuelist, &next->queuelist);
-			req->fifo_time = next->fifo_time;
-		}
-	}
-
-	/*
-	 * kill knowledge of next, this one is a goner
-	 */
-	deadline_remove_request(q, next);
-}
-
-/*
- * move request from sort list to dispatch queue.
- */
-static inline void
-deadline_move_to_dispatch(struct deadline_data *dd, struct request *rq)
-{
-	struct request_queue *q = rq->q;
-
-	/*
-	 * For a zoned block device, write requests must write lock their
-	 * target zone.
-	 */
-	blk_req_zone_write_lock(rq);
-
-	deadline_remove_request(q, rq);
-	elv_dispatch_add_tail(q, rq);
-}
-
-/*
- * move an entry to dispatch queue
- */
-static void
-deadline_move_request(struct deadline_data *dd, struct request *rq)
-{
-	const int data_dir = rq_data_dir(rq);
-
-	dd->next_rq[READ] = NULL;
-	dd->next_rq[WRITE] = NULL;
-	dd->next_rq[data_dir] = deadline_latter_request(rq);
-
-	/*
-	 * take it off the sort and fifo list, move
-	 * to dispatch queue
-	 */
-	deadline_move_to_dispatch(dd, rq);
-}
-
-/*
- * deadline_check_fifo returns 0 if there are no expired requests on the fifo,
- * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
- */
-static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
-{
-	struct request *rq = rq_entry_fifo(dd->fifo_list[ddir].next);
-
-	/*
-	 * rq is expired!
-	 */
-	if (time_after_eq(jiffies, (unsigned long)rq->fifo_time))
-		return 1;
-
-	return 0;
-}
-
-/*
- * For the specified data direction, return the next request to dispatch using
- * arrival ordered lists.
- */
-static struct request *
-deadline_fifo_request(struct deadline_data *dd, int data_dir)
-{
-	struct request *rq;
-
-	if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
-		return NULL;
-
-	if (list_empty(&dd->fifo_list[data_dir]))
-		return NULL;
-
-	rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
-	if (data_dir == READ || !blk_queue_is_zoned(rq->q))
-		return rq;
-
-	/*
-	 * Look for a write request that can be dispatched, that is one with
-	 * an unlocked target zone.
-	 */
-	list_for_each_entry(rq, &dd->fifo_list[WRITE], queuelist) {
-		if (blk_req_can_dispatch_to_zone(rq))
-			return rq;
-	}
-
-	return NULL;
-}
-
-/*
- * For the specified data direction, return the next request to dispatch using
- * sector position sorted lists.
- */
-static struct request *
-deadline_next_request(struct deadline_data *dd, int data_dir)
-{
-	struct request *rq;
-
-	if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
-		return NULL;
-
-	rq = dd->next_rq[data_dir];
-	if (!rq)
-		return NULL;
-
-	if (data_dir == READ || !blk_queue_is_zoned(rq->q))
-		return rq;
-
-	/*
-	 * Look for a write request that can be dispatched, that is one with
-	 * an unlocked target zone.
-	 */
-	while (rq) {
-		if (blk_req_can_dispatch_to_zone(rq))
-			return rq;
-		rq = deadline_latter_request(rq);
-	}
-
-	return NULL;
-}
-
-/*
- * deadline_dispatch_requests selects the best request according to
- * read/write expire, fifo_batch, etc
- */
-static int deadline_dispatch_requests(struct request_queue *q, int force)
-{
-	struct deadline_data *dd = q->elevator->elevator_data;
-	const int reads = !list_empty(&dd->fifo_list[READ]);
-	const int writes = !list_empty(&dd->fifo_list[WRITE]);
-	struct request *rq, *next_rq;
-	int data_dir;
-
-	/*
-	 * batches are currently reads XOR writes
-	 */
-	rq = deadline_next_request(dd, WRITE);
-	if (!rq)
-		rq = deadline_next_request(dd, READ);
-
-	if (rq && dd->batching < dd->fifo_batch)
-		/* we have a next request are still entitled to batch */
-		goto dispatch_request;
-
-	/*
-	 * at this point we are not running a batch. select the appropriate
-	 * data direction (read / write)
-	 */
-
-	if (reads) {
-		BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[READ]));
-
-		if (deadline_fifo_request(dd, WRITE) &&
-		    (dd->starved++ >= dd->writes_starved))
-			goto dispatch_writes;
-
-		data_dir = READ;
-
-		goto dispatch_find_request;
-	}
-
-	/*
-	 * there are either no reads or writes have been starved
-	 */
-
-	if (writes) {
-dispatch_writes:
-		BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[WRITE]));
-
-		dd->starved = 0;
-
-		data_dir = WRITE;
-
-		goto dispatch_find_request;
-	}
-
-	return 0;
-
-dispatch_find_request:
-	/*
-	 * we are not running a batch, find best request for selected data_dir
-	 */
-	next_rq = deadline_next_request(dd, data_dir);
-	if (deadline_check_fifo(dd, data_dir) || !next_rq) {
-		/*
-		 * A deadline has expired, the last request was in the other
-		 * direction, or we have run out of higher-sectored requests.
-		 * Start again from the request with the earliest expiry time.
-		 */
-		rq = deadline_fifo_request(dd, data_dir);
-	} else {
-		/*
-		 * The last req was the same dir and we have a next request in
-		 * sort order. No expired requests so continue on from here.
-		 */
-		rq = next_rq;
-	}
-
-	/*
-	 * For a zoned block device, if we only have writes queued and none of
-	 * them can be dispatched, rq will be NULL.
-	 */
-	if (!rq)
-		return 0;
-
-	dd->batching = 0;
-
-dispatch_request:
-	/*
-	 * rq is the selected appropriate request.
-	 */
-	dd->batching++;
-	deadline_move_request(dd, rq);
-
-	return 1;
-}
-
-/*
- * For zoned block devices, write unlock the target zone of completed
- * write requests.
- */
-static void
-deadline_completed_request(struct request_queue *q, struct request *rq)
-{
-	blk_req_zone_write_unlock(rq);
-}
-
-static void deadline_exit_queue(struct elevator_queue *e)
-{
-	struct deadline_data *dd = e->elevator_data;
-
-	BUG_ON(!list_empty(&dd->fifo_list[READ]));
-	BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
-
-	kfree(dd);
-}
-
-/*
- * initialize elevator private data (deadline_data).
- */
-static int deadline_init_queue(struct request_queue *q, struct elevator_type *e)
-{
-	struct deadline_data *dd;
-	struct elevator_queue *eq;
-
-	eq = elevator_alloc(q, e);
-	if (!eq)
-		return -ENOMEM;
-
-	dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
-	if (!dd) {
-		kobject_put(&eq->kobj);
-		return -ENOMEM;
-	}
-	eq->elevator_data = dd;
-
-	INIT_LIST_HEAD(&dd->fifo_list[READ]);
-	INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
-	dd->sort_list[READ] = RB_ROOT;
-	dd->sort_list[WRITE] = RB_ROOT;
-	dd->fifo_expire[READ] = read_expire;
-	dd->fifo_expire[WRITE] = write_expire;
-	dd->writes_starved = writes_starved;
-	dd->front_merges = 1;
-	dd->fifo_batch = fifo_batch;
-
-	spin_lock_irq(q->queue_lock);
-	q->elevator = eq;
-	spin_unlock_irq(q->queue_lock);
-	return 0;
-}
-
-/*
- * sysfs parts below
- */
-
-static ssize_t
-deadline_var_show(int var, char *page)
-{
-	return sprintf(page, "%d\n", var);
-}
-
-static void
-deadline_var_store(int *var, const char *page)
-{
-	char *p = (char *) page;
-
-	*var = simple_strtol(p, &p, 10);
-}
-
-#define SHOW_FUNCTION(__FUNC, __VAR, __CONV)				\
-static ssize_t __FUNC(struct elevator_queue *e, char *page)		\
-{									\
-	struct deadline_data *dd = e->elevator_data;			\
-	int __data = __VAR;						\
-	if (__CONV)							\
-		__data = jiffies_to_msecs(__data);			\
-	return deadline_var_show(__data, (page));			\
-}
-SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1);
-SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1);
-SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0);
-SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0);
-SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0);
-#undef SHOW_FUNCTION
-
-#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)			\
-static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)	\
-{									\
-	struct deadline_data *dd = e->elevator_data;			\
-	int __data;							\
-	deadline_var_store(&__data, (page));				\
-	if (__data < (MIN))						\
-		__data = (MIN);						\
-	else if (__data > (MAX))					\
-		__data = (MAX);						\
-	if (__CONV)							\
-		*(__PTR) = msecs_to_jiffies(__data);			\
-	else								\
-		*(__PTR) = __data;					\
-	return count;							\
-}
-STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
-STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
-STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
-STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0);
-STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0);
-#undef STORE_FUNCTION
-
-#define DD_ATTR(name) \
-	__ATTR(name, 0644, deadline_##name##_show, deadline_##name##_store)
-
-static struct elv_fs_entry deadline_attrs[] = {
-	DD_ATTR(read_expire),
-	DD_ATTR(write_expire),
-	DD_ATTR(writes_starved),
-	DD_ATTR(front_merges),
-	DD_ATTR(fifo_batch),
-	__ATTR_NULL
-};
-
-static struct elevator_type iosched_deadline = {
-	.ops.sq = {
-		.elevator_merge_fn = 		deadline_merge,
-		.elevator_merged_fn =		deadline_merged_request,
-		.elevator_merge_req_fn =	deadline_merged_requests,
-		.elevator_dispatch_fn =		deadline_dispatch_requests,
-		.elevator_completed_req_fn =	deadline_completed_request,
-		.elevator_add_req_fn =		deadline_add_request,
-		.elevator_former_req_fn =	elv_rb_former_request,
-		.elevator_latter_req_fn =	elv_rb_latter_request,
-		.elevator_init_fn =		deadline_init_queue,
-		.elevator_exit_fn =		deadline_exit_queue,
-	},
-
-	.elevator_attrs = deadline_attrs,
-	.elevator_name = "deadline",
-	.elevator_owner = THIS_MODULE,
-};
-
-static int __init deadline_init(void)
-{
-	return elv_register(&iosched_deadline);
-}
-
-static void __exit deadline_exit(void)
-{
-	elv_unregister(&iosched_deadline);
-}
-
-module_init(deadline_init);
-module_exit(deadline_exit);
-
-MODULE_AUTHOR("Jens Axboe");
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("deadline IO scheduler");