Merge branch 'upstream'

1 files changed, 878 insertions, 0 deletions

diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
new file mode 100644
index 00000000000..7929471d7df
--- /dev/null
+++ b/block/deadline-iosched.c
@@ -0,0 +1,878 @@
+/*
+ *  linux/drivers/block/deadline-iosched.c
+ *
+ *  Deadline i/o scheduler.
+ *
+ *  Copyright (C) 2002 Jens Axboe <axboe@suse.de>
+ */
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/blkdev.h>
+#include <linux/elevator.h>
+#include <linux/bio.h>
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/compiler.h>
+#include <linux/hash.h>
+#include <linux/rbtree.h>
+
+/*
+ * See Documentation/block/deadline-iosched.txt
+ */
+static int read_expire = HZ / 2;  /* max time before a read is submitted. */
+static int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
+static int writes_starved = 2;    /* max times reads can starve a write */
+static 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 list_entry_hash(ptr)	list_entry((ptr), struct deadline_rq, hash)
+#define ON_HASH(drq)		(drq)->on_hash
+
+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 deadline_rq *next_drq[2];
+	struct list_head *hash;		/* request hash */
+	unsigned int batching;		/* number of sequential requests made */
+	sector_t last_sector;		/* head position */
+	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;
+
+	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 list_head hash;
+	char on_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)
+
+/*
+ * the back merge hash support functions
+ */
+static inline void __deadline_del_drq_hash(struct deadline_rq *drq)
+{
+	drq->on_hash = 0;
+	list_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));
+
+	drq->on_hash = 1;
+	list_add(&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 list_head *head = &dd->hash[DL_HASH_FN(rq_hash_key(rq))];
+
+	if (ON_HASH(drq) && drq->hash.prev != head) {
+		list_del(&drq->hash);
+		list_add(&drq->hash, head);
+	}
+}
+
+static struct request *
+deadline_find_drq_hash(struct deadline_data *dd, sector_t offset)
+{
+	struct list_head *hash_list = &dd->hash[DL_HASH_FN(offset)];
+	struct list_head *entry, *next = hash_list->next;
+
+	while ((entry = next) != hash_list) {
+		struct deadline_rq *drq = list_entry_hash(entry);
+		struct request *__rq = drq->request;
+
+		next = entry->next;
+		
+		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_NONE		(2)
+#define RB_EMPTY(root)	((root)->rb_node == NULL)
+#define ON_RB(node)	((node)->rb_color != RB_NONE)
+#define RB_CLEAR(node)	((node)->rb_color = RB_NONE)
+#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;
+}
+
+static void
+deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
+{
+	struct deadline_rq *__alias;
+
+	drq->rb_key = rq_rb_key(drq->request);
+
+retry:
+	__alias = __deadline_add_drq_rb(dd, drq);
+	if (!__alias) {
+		rb_insert_color(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
+		return;
+	}
+
+	deadline_move_request(dd, __alias);
+	goto retry;
+}
+
+static inline void
+deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
+{
+	const int data_dir = rq_data_dir(drq->request);
+
+	if (dd->next_drq[data_dir] == drq) {
+		struct rb_node *rbnext = rb_next(&drq->rb_node);
+
+		dd->next_drq[data_dir] = NULL;
+		if (rbnext)
+			dd->next_drq[data_dir] = rb_entry_drq(rbnext);
+	}
+
+	BUG_ON(!ON_RB(&drq->rb_node));
+	rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
+	RB_CLEAR(&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;
+	}
+
+	return NULL;
+}
+
+/*
+ * 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
+ */
+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(drq->request);
+
+	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);
+}
+
+/*
+ * remove rq from rbtree, fifo, and hash
+ */
+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);
+}
+
+static int
+deadline_merge(request_queue_t *q, struct request **req, struct bio *bio)
+{
+	struct deadline_data *dd = q->elevator->elevator_data;
+	struct request *__rq;
+	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);
+
+		__rq = deadline_find_drq_rb(dd, rb_key, bio_data_dir(bio));
+		if (__rq) {
+			BUG_ON(rb_key != rq_rb_key(__rq));
+
+			if (elv_rq_merge_ok(__rq, bio)) {
+				ret = ELEVATOR_FRONT_MERGE;
+				goto out;
+			}
+		}
+	}
+
+	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)
+{
+	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);
+	}
+}
+
+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
+	 */
+	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;
+		}
+	}
+
+	/*
+	 * 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 deadline_rq *drq)
+{
+	request_queue_t *q = drq->request->q;
+
+	deadline_remove_request(q, drq->request);
+	elv_dispatch_add_tail(q, drq->request);
+}
+
+/*
+ * move an entry to dispatch queue
+ */
+static void
+deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq)
+{
+	const int data_dir = rq_data_dir(drq->request);
+	struct rb_node *rbnext = rb_next(&drq->rb_node);
+
+	dd->next_drq[READ] = NULL;
+	dd->next_drq[WRITE] = NULL;
+
+	if (rbnext)
+		dd->next_drq[data_dir] = rb_entry_drq(rbnext);
+	
+	dd->last_sector = drq->request->sector + drq->request->nr_sectors;
+
+	/*
+	 * take it off the sort and fifo list, move
+	 * to dispatch queue
+	 */
+	deadline_move_to_dispatch(dd, drq);
+}
+
+#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);
+
+	/*
+	 * drq is expired!
+	 */
+	if (time_after(jiffies, drq->expires))
+		return 1;
+
+	return 0;
+}
+
+/*
+ * deadline_dispatch_requests selects the best request according to
+ * read/write expire, fifo_batch, etc
+ */
+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;
+	int data_dir;
+
+	/*
+	 * batches are currently reads XOR writes
+	 */
+	if (dd->next_drq[WRITE])
+		drq = dd->next_drq[WRITE];
+	else
+		drq = dd->next_drq[READ];
+
+	if (drq) {
+		/* we have a "next request" */
+		
+		if (dd->last_sector != drq->request->sector)
+			/* end the batch on a non sequential request */
+			dd->batching += dd->fifo_batch;
+		
+		if (dd->batching < dd->fifo_batch)
+			/* we 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(&dd->sort_list[READ]));
+
+		if (writes && (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(&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
+	 */
+	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);
+		
+	} else if (dd->next_drq[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];
+	} else {
+		/*
+		 * 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);
+	}
+
+dispatch_request:
+	/*
+	 * drq is the selected appropriate request.
+	 */
+	dd->batching++;
+	deadline_move_request(dd, drq);
+
+	return 1;
+}
+
+static int deadline_queue_empty(request_queue_t *q)
+{
+	struct deadline_data *dd = q->elevator->elevator_data;
+
+	return list_empty(&dd->fifo_list[WRITE])
+		&& 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;
+
+	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
+ */
+static int deadline_init_queue(request_queue_t *q, elevator_t *e)
+{
+	struct deadline_data *dd;
+	int i;
+
+	if (!drq_pool)
+		return -ENOMEM;
+
+	dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
+	if (!dd)
+		return -ENOMEM;
+	memset(dd, 0, sizeof(*dd));
+
+	dd->hash = kmalloc_node(sizeof(struct list_head)*DL_HASH_ENTRIES,
+				GFP_KERNEL, q->node);
+	if (!dd->hash) {
+		kfree(dd);
+		return -ENOMEM;
+	}
+
+	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 -ENOMEM;
+	}
+
+	for (i = 0; i < DL_HASH_ENTRIES; i++)
+		INIT_LIST_HEAD(&dd->hash[i]);
+
+	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;
+	e->elevator_data = dd;
+	return 0;
+}
+
+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(&drq->rb_node);
+		drq->request = rq;
+
+		INIT_LIST_HEAD(&drq->hash);
+		drq->on_hash = 0;
+
+		INIT_LIST_HEAD(&drq->fifo);
+
+		rq->elevator_private = drq;
+		return 0;
+	}
+
+	return 1;
+}
+
+/*
+ * sysfs parts below
+ */
+struct deadline_fs_entry {
+	struct attribute attr;
+	ssize_t (*show)(struct deadline_data *, char *);
+	ssize_t (*store)(struct deadline_data *, const char *, size_t);
+};
+
+static ssize_t
+deadline_var_show(int var, char *page)
+{
+	return sprintf(page, "%d\n", var);
+}
+
+static ssize_t
+deadline_var_store(int *var, const char *page, size_t count)
+{
+	char *p = (char *) page;
+
+	*var = simple_strtol(p, &p, 10);
+	return count;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV)				\
+static ssize_t __FUNC(struct deadline_data *dd, char *page)		\
+{									\
+	int __data = __VAR;					\
+	if (__CONV)							\
+		__data = jiffies_to_msecs(__data);			\
+	return deadline_var_show(__data, (page));			\
+}
+SHOW_FUNCTION(deadline_readexpire_show, dd->fifo_expire[READ], 1);
+SHOW_FUNCTION(deadline_writeexpire_show, dd->fifo_expire[WRITE], 1);
+SHOW_FUNCTION(deadline_writesstarved_show, dd->writes_starved, 0);
+SHOW_FUNCTION(deadline_frontmerges_show, dd->front_merges, 0);
+SHOW_FUNCTION(deadline_fifobatch_show, dd->fifo_batch, 0);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)			\
+static ssize_t __FUNC(struct deadline_data *dd, const char *page, size_t count)	\
+{									\
+	int __data;							\
+	int ret = deadline_var_store(&__data, (page), count);		\
+	if (__data < (MIN))						\
+		__data = (MIN);						\
+	else if (__data > (MAX))					\
+		__data = (MAX);						\
+	if (__CONV)							\
+		*(__PTR) = msecs_to_jiffies(__data);			\
+	else								\
+		*(__PTR) = __data;					\
+	return ret;							\
+}
+STORE_FUNCTION(deadline_readexpire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
+STORE_FUNCTION(deadline_writeexpire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
+STORE_FUNCTION(deadline_writesstarved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
+STORE_FUNCTION(deadline_frontmerges_store, &dd->front_merges, 0, 1, 0);
+STORE_FUNCTION(deadline_fifobatch_store, &dd->fifo_batch, 0, INT_MAX, 0);
+#undef STORE_FUNCTION
+
+static struct deadline_fs_entry deadline_readexpire_entry = {
+	.attr = {.name = "read_expire", .mode = S_IRUGO | S_IWUSR },
+	.show = deadline_readexpire_show,
+	.store = deadline_readexpire_store,
+};
+static struct deadline_fs_entry deadline_writeexpire_entry = {
+	.attr = {.name = "write_expire", .mode = S_IRUGO | S_IWUSR },
+	.show = deadline_writeexpire_show,
+	.store = deadline_writeexpire_store,
+};
+static struct deadline_fs_entry deadline_writesstarved_entry = {
+	.attr = {.name = "writes_starved", .mode = S_IRUGO | S_IWUSR },
+	.show = deadline_writesstarved_show,
+	.store = deadline_writesstarved_store,
+};
+static struct deadline_fs_entry deadline_frontmerges_entry = {
+	.attr = {.name = "front_merges", .mode = S_IRUGO | S_IWUSR },
+	.show = deadline_frontmerges_show,
+	.store = deadline_frontmerges_store,
+};
+static struct deadline_fs_entry deadline_fifobatch_entry = {
+	.attr = {.name = "fifo_batch", .mode = S_IRUGO | S_IWUSR },
+	.show = deadline_fifobatch_show,
+	.store = deadline_fifobatch_store,
+};
+
+static struct attribute *default_attrs[] = {
+	&deadline_readexpire_entry.attr,
+	&deadline_writeexpire_entry.attr,
+	&deadline_writesstarved_entry.attr,
+	&deadline_frontmerges_entry.attr,
+	&deadline_fifobatch_entry.attr,
+	NULL,
+};
+
+#define to_deadline(atr) container_of((atr), struct deadline_fs_entry, attr)
+
+static ssize_t
+deadline_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
+{
+	elevator_t *e = container_of(kobj, elevator_t, kobj);
+	struct deadline_fs_entry *entry = to_deadline(attr);
+
+	if (!entry->show)
+		return -EIO;
+
+	return entry->show(e->elevator_data, page);
+}
+
+static ssize_t
+deadline_attr_store(struct kobject *kobj, struct attribute *attr,
+		    const char *page, size_t length)
+{
+	elevator_t *e = container_of(kobj, elevator_t, kobj);
+	struct deadline_fs_entry *entry = to_deadline(attr);
+
+	if (!entry->store)
+		return -EIO;
+
+	return entry->store(e->elevator_data, page, length);
+}
+
+static struct sysfs_ops deadline_sysfs_ops = {
+	.show	= deadline_attr_show,
+	.store	= deadline_attr_store,
+};
+
+static struct kobj_type deadline_ktype = {
+	.sysfs_ops	= &deadline_sysfs_ops,
+	.default_attrs	= default_attrs,
+};
+
+static struct elevator_type iosched_deadline = {
+	.ops = {
+		.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_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_init_fn =		deadline_init_queue,
+		.elevator_exit_fn =		deadline_exit_queue,
+	},
+
+	.elevator_ktype = &deadline_ktype,
+	.elevator_name = "deadline",
+	.elevator_owner = THIS_MODULE,
+};
+
+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;
+}
+
+static void __exit deadline_exit(void)
+{
+	kmem_cache_destroy(drq_pool);
+	elv_unregister(&iosched_deadline);
+}
+
+module_init(deadline_init);
+module_exit(deadline_exit);
+
+MODULE_AUTHOR("Jens Axboe");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("deadline IO scheduler");