1 files changed, 74 insertions, 390 deletions

diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index c7ca9f0b6498..b7c5b34cb7b4 100644
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -1,7 +1,7 @@
 /*
  *  Deadline i/o scheduler.
  *
- *  Copyright (C) 2002 Jens Axboe <axboe@suse.de>
+ *  Copyright (C) 2002 Jens Axboe <axboe@kernel.dk>
  */
 #include <linux/kernel.h>
 #include <linux/fs.h>
@@ -12,7 +12,6 @@
 #include <linux/slab.h>
 #include <linux/init.h>
 #include <linux/compiler.h>
-#include <linux/hash.h>
 #include <linux/rbtree.h>
 
 /*
@@ -24,13 +23,6 @@ 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. */
 
-static const int deadline_hash_shift = 5;
-#define DL_HASH_BLOCK(sec)	((sec) >> 3)
-#define DL_HASH_FN(sec)		(hash_long(DL_HASH_BLOCK((sec)), deadline_hash_shift))
-#define DL_HASH_ENTRIES		(1 << deadline_hash_shift)
-#define rq_hash_key(rq)		((rq)->sector + (rq)->nr_sectors)
-#define ON_HASH(drq)		(!hlist_unhashed(&(drq)->hash))
-
 struct deadline_data {
 	/*
 	 * run time data
@@ -45,8 +37,7 @@ struct deadline_data {
 	/*
 	 * next in sort order. read, write or both are NULL
 	 */
-	struct deadline_rq *next_drq[2];
-	struct hlist_head *hash;	/* request hash */
+	struct request *next_rq[2];
 	unsigned int batching;		/* number of sequential requests made */
 	sector_t last_sector;		/* head position */
 	unsigned int starved;		/* times reads have starved writes */
@@ -58,240 +49,69 @@ struct deadline_data {
 	int fifo_batch;
 	int writes_starved;
 	int front_merges;
-
-	mempool_t *drq_pool;
 };
 
-/*
- * pre-request data.
- */
-struct deadline_rq {
-	/*
-	 * rbtree index, key is the starting offset
-	 */
-	struct rb_node rb_node;
-	sector_t rb_key;
-
-	struct request *request;
-
-	/*
-	 * request hash, key is the ending offset (for back merge lookup)
-	 */
-	struct hlist_node hash;
-
-	/*
-	 * expire fifo
-	 */
-	struct list_head fifo;
-	unsigned long expires;
-};
-
-static void deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq);
-
-static kmem_cache_t *drq_pool;
-
-#define RQ_DATA(rq)	((struct deadline_rq *) (rq)->elevator_private)
+static void deadline_move_request(struct deadline_data *, struct request *);
 
-/*
- * the back merge hash support functions
- */
-static inline void __deadline_del_drq_hash(struct deadline_rq *drq)
-{
-	hlist_del_init(&drq->hash);
-}
-
-static inline void deadline_del_drq_hash(struct deadline_rq *drq)
-{
-	if (ON_HASH(drq))
-		__deadline_del_drq_hash(drq);
-}
-
-static inline void
-deadline_add_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
-{
-	struct request *rq = drq->request;
-
-	BUG_ON(ON_HASH(drq));
-
-	hlist_add_head(&drq->hash, &dd->hash[DL_HASH_FN(rq_hash_key(rq))]);
-}
-
-/*
- * move hot entry to front of chain
- */
-static inline void
-deadline_hot_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
-{
-	struct request *rq = drq->request;
-	struct hlist_head *head = &dd->hash[DL_HASH_FN(rq_hash_key(rq))];
-
-	if (ON_HASH(drq) && &drq->hash != head->first) {
-		hlist_del(&drq->hash);
-		hlist_add_head(&drq->hash, head);
-	}
-}
-
-static struct request *
-deadline_find_drq_hash(struct deadline_data *dd, sector_t offset)
-{
-	struct hlist_head *hash_list = &dd->hash[DL_HASH_FN(offset)];
-	struct hlist_node *entry, *next;
-	struct deadline_rq *drq;
-
-	hlist_for_each_entry_safe(drq, entry, next, hash_list, hash) {
-		struct request *__rq = drq->request;
-
-		BUG_ON(!ON_HASH(drq));
-
-		if (!rq_mergeable(__rq)) {
-			__deadline_del_drq_hash(drq);
-			continue;
-		}
-
-		if (rq_hash_key(__rq) == offset)
-			return __rq;
-	}
-
-	return NULL;
-}
-
-/*
- * rb tree support functions
- */
-#define rb_entry_drq(node)	rb_entry((node), struct deadline_rq, rb_node)
-#define DRQ_RB_ROOT(dd, drq)	(&(dd)->sort_list[rq_data_dir((drq)->request)])
-#define rq_rb_key(rq)		(rq)->sector
-
-static struct deadline_rq *
-__deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
-{
-	struct rb_node **p = &DRQ_RB_ROOT(dd, drq)->rb_node;
-	struct rb_node *parent = NULL;
-	struct deadline_rq *__drq;
-
-	while (*p) {
-		parent = *p;
-		__drq = rb_entry_drq(parent);
-
-		if (drq->rb_key < __drq->rb_key)
-			p = &(*p)->rb_left;
-		else if (drq->rb_key > __drq->rb_key)
-			p = &(*p)->rb_right;
-		else
-			return __drq;
-	}
-
-	rb_link_node(&drq->rb_node, parent, p);
-	return NULL;
-}
+#define RQ_RB_ROOT(dd, rq)	(&(dd)->sort_list[rq_data_dir((rq))])
 
 static void
-deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
+deadline_add_rq_rb(struct deadline_data *dd, struct request *rq)
 {
-	struct deadline_rq *__alias;
-
-	drq->rb_key = rq_rb_key(drq->request);
+	struct rb_root *root = RQ_RB_ROOT(dd, rq);
+	struct request *__alias;
 
 retry:
-	__alias = __deadline_add_drq_rb(dd, drq);
-	if (!__alias) {
-		rb_insert_color(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
-		return;
+	__alias = elv_rb_add(root, rq);
+	if (unlikely(__alias)) {
+		deadline_move_request(dd, __alias);
+		goto retry;
 	}
-
-	deadline_move_request(dd, __alias);
-	goto retry;
 }
 
 static inline void
-deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
+deadline_del_rq_rb(struct deadline_data *dd, struct request *rq)
 {
-	const int data_dir = rq_data_dir(drq->request);
+	const int data_dir = rq_data_dir(rq);
 
-	if (dd->next_drq[data_dir] == drq) {
-		struct rb_node *rbnext = rb_next(&drq->rb_node);
+	if (dd->next_rq[data_dir] == rq) {
+		struct rb_node *rbnext = rb_next(&rq->rb_node);
 
-		dd->next_drq[data_dir] = NULL;
+		dd->next_rq[data_dir] = NULL;
 		if (rbnext)
-			dd->next_drq[data_dir] = rb_entry_drq(rbnext);
-	}
-
-	BUG_ON(!RB_EMPTY_NODE(&drq->rb_node));
-	rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
-	RB_CLEAR_NODE(&drq->rb_node);
-}
-
-static struct request *
-deadline_find_drq_rb(struct deadline_data *dd, sector_t sector, int data_dir)
-{
-	struct rb_node *n = dd->sort_list[data_dir].rb_node;
-	struct deadline_rq *drq;
-
-	while (n) {
-		drq = rb_entry_drq(n);
-
-		if (sector < drq->rb_key)
-			n = n->rb_left;
-		else if (sector > drq->rb_key)
-			n = n->rb_right;
-		else
-			return drq->request;
+			dd->next_rq[data_dir] = rb_entry_rq(rbnext);
 	}
 
-	return NULL;
+	elv_rb_del(RQ_RB_ROOT(dd, rq), rq);
 }
 
 /*
- * deadline_find_first_drq finds the first (lowest sector numbered) request
- * for the specified data_dir. Used to sweep back to the start of the disk
- * (1-way elevator) after we process the last (highest sector) request.
- */
-static struct deadline_rq *
-deadline_find_first_drq(struct deadline_data *dd, int data_dir)
-{
-	struct rb_node *n = dd->sort_list[data_dir].rb_node;
-
-	for (;;) {
-		if (n->rb_left == NULL)
-			return rb_entry_drq(n);
-		
-		n = n->rb_left;
-	}
-}
-
-/*
- * add drq to rbtree and fifo
+ * 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;
-	struct deadline_rq *drq = RQ_DATA(rq);
+	const int data_dir = rq_data_dir(rq);
 
-	const int data_dir = rq_data_dir(drq->request);
+	deadline_add_rq_rb(dd, rq);
 
-	deadline_add_drq_rb(dd, drq);
 	/*
 	 * set expire time (only used for reads) and add to fifo list
 	 */
-	drq->expires = jiffies + dd->fifo_expire[data_dir];
-	list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]);
-
-	if (rq_mergeable(rq))
-		deadline_add_drq_hash(dd, drq);
+	rq_set_fifo_time(rq, jiffies + dd->fifo_expire[data_dir]);
+	list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]);
 }
 
 /*
- * remove rq from rbtree, fifo, and hash
+ * remove rq from rbtree and fifo.
  */
 static void deadline_remove_request(request_queue_t *q, struct request *rq)
 {
-	struct deadline_rq *drq = RQ_DATA(rq);
 	struct deadline_data *dd = q->elevator->elevator_data;
 
-	list_del_init(&drq->fifo);
-	deadline_del_drq_rb(dd, drq);
-	deadline_del_drq_hash(drq);
+	rq_fifo_clear(rq);
+	deadline_del_rq_rb(dd, rq);
 }
 
 static int
@@ -302,27 +122,14 @@ deadline_merge(request_queue_t *q, struct request **req, struct bio *bio)
 	int ret;
 
 	/*
-	 * see if the merge hash can satisfy a back merge
-	 */
-	__rq = deadline_find_drq_hash(dd, bio->bi_sector);
-	if (__rq) {
-		BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector);
-
-		if (elv_rq_merge_ok(__rq, bio)) {
-			ret = ELEVATOR_BACK_MERGE;
-			goto out;
-		}
-	}
-
-	/*
 	 * check for front merge
 	 */
 	if (dd->front_merges) {
-		sector_t rb_key = bio->bi_sector + bio_sectors(bio);
+		sector_t sector = bio->bi_sector + bio_sectors(bio);
 
-		__rq = deadline_find_drq_rb(dd, rb_key, bio_data_dir(bio));
+		__rq = elv_rb_find(&dd->sort_list[bio_data_dir(bio)], sector);
 		if (__rq) {
-			BUG_ON(rb_key != rq_rb_key(__rq));
+			BUG_ON(sector != __rq->sector);
 
 			if (elv_rq_merge_ok(__rq, bio)) {
 				ret = ELEVATOR_FRONT_MERGE;
@@ -333,29 +140,21 @@ deadline_merge(request_queue_t *q, struct request **req, struct bio *bio)
 
 	return ELEVATOR_NO_MERGE;
 out:
-	if (ret)
-		deadline_hot_drq_hash(dd, RQ_DATA(__rq));
 	*req = __rq;
 	return ret;
 }
 
-static void deadline_merged_request(request_queue_t *q, struct request *req)
+static void deadline_merged_request(request_queue_t *q, struct request *req,
+				    int type)
 {
 	struct deadline_data *dd = q->elevator->elevator_data;
-	struct deadline_rq *drq = RQ_DATA(req);
-
-	/*
-	 * hash always needs to be repositioned, key is end sector
-	 */
-	deadline_del_drq_hash(drq);
-	deadline_add_drq_hash(dd, drq);
 
 	/*
 	 * if the merge was a front merge, we need to reposition request
 	 */
-	if (rq_rb_key(req) != drq->rb_key) {
-		deadline_del_drq_rb(dd, drq);
-		deadline_add_drq_rb(dd, drq);
+	if (type == ELEVATOR_FRONT_MERGE) {
+		elv_rb_del(RQ_RB_ROOT(dd, req), req);
+		deadline_add_rq_rb(dd, req);
 	}
 }
 
@@ -363,33 +162,14 @@ static void
 deadline_merged_requests(request_queue_t *q, struct request *req,
 			 struct request *next)
 {
-	struct deadline_data *dd = q->elevator->elevator_data;
-	struct deadline_rq *drq = RQ_DATA(req);
-	struct deadline_rq *dnext = RQ_DATA(next);
-
-	BUG_ON(!drq);
-	BUG_ON(!dnext);
-
 	/*
-	 * reposition drq (this is the merged request) in hash, and in rbtree
-	 * in case of a front merge
+	 * if next expires before rq, assign its expire time to rq
+	 * and move into next position (next will be deleted) in fifo
 	 */
-	deadline_del_drq_hash(drq);
-	deadline_add_drq_hash(dd, drq);
-
-	if (rq_rb_key(req) != drq->rb_key) {
-		deadline_del_drq_rb(dd, drq);
-		deadline_add_drq_rb(dd, drq);
-	}
-
-	/*
-	 * if dnext expires before drq, assign its expire time to drq
-	 * and move into dnext position (dnext will be deleted) in fifo
-	 */
-	if (!list_empty(&drq->fifo) && !list_empty(&dnext->fifo)) {
-		if (time_before(dnext->expires, drq->expires)) {
-			list_move(&drq->fifo, &dnext->fifo);
-			drq->expires = dnext->expires;
+	if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
+		if (time_before(rq_fifo_time(next), rq_fifo_time(req))) {
+			list_move(&req->queuelist, &next->queuelist);
+			rq_set_fifo_time(req, rq_fifo_time(next));
 		}
 	}
 
@@ -403,52 +183,50 @@ deadline_merged_requests(request_queue_t *q, struct request *req,
  * move request from sort list to dispatch queue.
  */
 static inline void
-deadline_move_to_dispatch(struct deadline_data *dd, struct deadline_rq *drq)
+deadline_move_to_dispatch(struct deadline_data *dd, struct request *rq)
 {
-	request_queue_t *q = drq->request->q;
+	request_queue_t *q = rq->q;
 
-	deadline_remove_request(q, drq->request);
-	elv_dispatch_add_tail(q, drq->request);
+	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 deadline_rq *drq)
+deadline_move_request(struct deadline_data *dd, struct request *rq)
 {
-	const int data_dir = rq_data_dir(drq->request);
-	struct rb_node *rbnext = rb_next(&drq->rb_node);
+	const int data_dir = rq_data_dir(rq);
+	struct rb_node *rbnext = rb_next(&rq->rb_node);
 
-	dd->next_drq[READ] = NULL;
-	dd->next_drq[WRITE] = NULL;
+	dd->next_rq[READ] = NULL;
+	dd->next_rq[WRITE] = NULL;
 
 	if (rbnext)
-		dd->next_drq[data_dir] = rb_entry_drq(rbnext);
+		dd->next_rq[data_dir] = rb_entry_rq(rbnext);
 	
-	dd->last_sector = drq->request->sector + drq->request->nr_sectors;
+	dd->last_sector = rq->sector + rq->nr_sectors;
 
 	/*
 	 * take it off the sort and fifo list, move
 	 * to dispatch queue
 	 */
-	deadline_move_to_dispatch(dd, drq);
+	deadline_move_to_dispatch(dd, rq);
 }
 
-#define list_entry_fifo(ptr)	list_entry((ptr), struct deadline_rq, fifo)
-
 /*
  * deadline_check_fifo returns 0 if there are no expired reads 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 deadline_rq *drq = list_entry_fifo(dd->fifo_list[ddir].next);
+	struct request *rq = rq_entry_fifo(dd->fifo_list[ddir].next);
 
 	/*
-	 * drq is expired!
+	 * rq is expired!
 	 */
-	if (time_after(jiffies, drq->expires))
+	if (time_after(jiffies, rq_fifo_time(rq)))
 		return 1;
 
 	return 0;
@@ -463,21 +241,21 @@ static int deadline_dispatch_requests(request_queue_t *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 deadline_rq *drq;
+	struct request *rq;
 	int data_dir;
 
 	/*
 	 * batches are currently reads XOR writes
 	 */
-	if (dd->next_drq[WRITE])
-		drq = dd->next_drq[WRITE];
+	if (dd->next_rq[WRITE])
+		rq = dd->next_rq[WRITE];
 	else
-		drq = dd->next_drq[READ];
+		rq = dd->next_rq[READ];
 
-	if (drq) {
+	if (rq) {
 		/* we have a "next request" */
 		
-		if (dd->last_sector != drq->request->sector)
+		if (dd->last_sector != rq->sector)
 			/* end the batch on a non sequential request */
 			dd->batching += dd->fifo_batch;
 		
@@ -526,30 +304,33 @@ dispatch_find_request:
 	if (deadline_check_fifo(dd, data_dir)) {
 		/* An expired request exists - satisfy it */
 		dd->batching = 0;
-		drq = list_entry_fifo(dd->fifo_list[data_dir].next);
+		rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
 		
-	} else if (dd->next_drq[data_dir]) {
+	} else if (dd->next_rq[data_dir]) {
 		/*
 		 * The last req was the same dir and we have a next request in
 		 * sort order. No expired requests so continue on from here.
 		 */
-		drq = dd->next_drq[data_dir];
+		rq = dd->next_rq[data_dir];
 	} else {
+		struct rb_node *node;
 		/*
 		 * The last req was the other direction or we have run out of
 		 * higher-sectored requests. Go back to the lowest sectored
 		 * request (1 way elevator) and start a new batch.
 		 */
 		dd->batching = 0;
-		drq = deadline_find_first_drq(dd, data_dir);
+		node = rb_first(&dd->sort_list[data_dir]);
+		if (node)
+			rq = rb_entry_rq(node);
 	}
 
 dispatch_request:
 	/*
-	 * drq is the selected appropriate request.
+	 * rq is the selected appropriate request.
 	 */
 	dd->batching++;
-	deadline_move_request(dd, drq);
+	deadline_move_request(dd, rq);
 
 	return 1;
 }
@@ -562,30 +343,6 @@ static int deadline_queue_empty(request_queue_t *q)
 		&& list_empty(&dd->fifo_list[READ]);
 }
 
-static struct request *
-deadline_former_request(request_queue_t *q, struct request *rq)
-{
-	struct deadline_rq *drq = RQ_DATA(rq);
-	struct rb_node *rbprev = rb_prev(&drq->rb_node);
-
-	if (rbprev)
-		return rb_entry_drq(rbprev)->request;
-
-	return NULL;
-}
-
-static struct request *
-deadline_latter_request(request_queue_t *q, struct request *rq)
-{
-	struct deadline_rq *drq = RQ_DATA(rq);
-	struct rb_node *rbnext = rb_next(&drq->rb_node);
-
-	if (rbnext)
-		return rb_entry_drq(rbnext)->request;
-
-	return NULL;
-}
-
 static void deadline_exit_queue(elevator_t *e)
 {
 	struct deadline_data *dd = e->elevator_data;
@@ -593,46 +350,21 @@ static void deadline_exit_queue(elevator_t *e)
 	BUG_ON(!list_empty(&dd->fifo_list[READ]));
 	BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
 
-	mempool_destroy(dd->drq_pool);
-	kfree(dd->hash);
 	kfree(dd);
 }
 
 /*
- * initialize elevator private data (deadline_data), and alloc a drq for
- * each request on the free lists
+ * initialize elevator private data (deadline_data).
  */
 static void *deadline_init_queue(request_queue_t *q, elevator_t *e)
 {
 	struct deadline_data *dd;
-	int i;
-
-	if (!drq_pool)
-		return NULL;
 
 	dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
 	if (!dd)
 		return NULL;
 	memset(dd, 0, sizeof(*dd));
 
-	dd->hash = kmalloc_node(sizeof(struct hlist_head)*DL_HASH_ENTRIES,
-				GFP_KERNEL, q->node);
-	if (!dd->hash) {
-		kfree(dd);
-		return NULL;
-	}
-
-	dd->drq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
-					mempool_free_slab, drq_pool, q->node);
-	if (!dd->drq_pool) {
-		kfree(dd->hash);
-		kfree(dd);
-		return NULL;
-	}
-
-	for (i = 0; i < DL_HASH_ENTRIES; i++)
-		INIT_HLIST_HEAD(&dd->hash[i]);
-
 	INIT_LIST_HEAD(&dd->fifo_list[READ]);
 	INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
 	dd->sort_list[READ] = RB_ROOT;
@@ -645,39 +377,6 @@ static void *deadline_init_queue(request_queue_t *q, elevator_t *e)
 	return dd;
 }
 
-static void deadline_put_request(request_queue_t *q, struct request *rq)
-{
-	struct deadline_data *dd = q->elevator->elevator_data;
-	struct deadline_rq *drq = RQ_DATA(rq);
-
-	mempool_free(drq, dd->drq_pool);
-	rq->elevator_private = NULL;
-}
-
-static int
-deadline_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
-		     gfp_t gfp_mask)
-{
-	struct deadline_data *dd = q->elevator->elevator_data;
-	struct deadline_rq *drq;
-
-	drq = mempool_alloc(dd->drq_pool, gfp_mask);
-	if (drq) {
-		memset(drq, 0, sizeof(*drq));
-		RB_CLEAR_NODE(&drq->rb_node);
-		drq->request = rq;
-
-		INIT_HLIST_NODE(&drq->hash);
-
-		INIT_LIST_HEAD(&drq->fifo);
-
-		rq->elevator_private = drq;
-		return 0;
-	}
-
-	return 1;
-}
-
 /*
  * sysfs parts below
  */
@@ -757,10 +456,8 @@ static struct elevator_type iosched_deadline = {
 		.elevator_dispatch_fn =		deadline_dispatch_requests,
 		.elevator_add_req_fn =		deadline_add_request,
 		.elevator_queue_empty_fn =	deadline_queue_empty,
-		.elevator_former_req_fn =	deadline_former_request,
-		.elevator_latter_req_fn =	deadline_latter_request,
-		.elevator_set_req_fn =		deadline_set_request,
-		.elevator_put_req_fn = 		deadline_put_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,
 	},
@@ -772,24 +469,11 @@ static struct elevator_type iosched_deadline = {
 
 static int __init deadline_init(void)
 {
-	int ret;
-
-	drq_pool = kmem_cache_create("deadline_drq", sizeof(struct deadline_rq),
-				     0, 0, NULL, NULL);
-
-	if (!drq_pool)
-		return -ENOMEM;
-
-	ret = elv_register(&iosched_deadline);
-	if (ret)
-		kmem_cache_destroy(drq_pool);
-
-	return ret;
+	return elv_register(&iosched_deadline);
 }
 
 static void __exit deadline_exit(void)
 {
-	kmem_cache_destroy(drq_pool);
 	elv_unregister(&iosched_deadline);
 }