Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 967 insertions, 0 deletions

diff --git a/drivers/block/deadline-iosched.c b/drivers/block/deadline-iosched.c
new file mode 100644
index 000000000000..d63d34c671f7
--- /dev/null
+++ b/drivers/block/deadline-iosched.c
@@ -0,0 +1,967 @@
+/*
+ *  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 *dispatch;     /* driver dispatch queue */
+        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 void
+deadline_remove_merge_hints(request_queue_t *q, struct deadline_rq *drq)
+{
+        deadline_del_drq_hash(drq);
+
+        if (q->last_merge == drq->request)
+                q->last_merge = NULL;
+}
+
+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);
+        }
+
+        if (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 inline 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);
+
+                if (!q->last_merge)
+                        q->last_merge = rq;
+        }
+}
+
+/*
+ * 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);
+
+        if (drq) {
+                struct deadline_data *dd = q->elevator->elevator_data;
+
+                list_del_init(&drq->fifo);
+                deadline_remove_merge_hints(q, drq);
+                deadline_del_drq_rb(dd, 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;
+
+        /*
+         * try last_merge to avoid going to hash
+         */
+        ret = elv_try_last_merge(q, bio);
+        if (ret != ELEVATOR_NO_MERGE) {
+                __rq = q->last_merge;
+                goto out_insert;
+        }
+
+        /*
+         * 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:
+        q->last_merge = __rq;
+out_insert:
+        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);
+        }
+
+        q->last_merge = req;
+}
+
+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);
+        list_add_tail(&drq->request->queuelist, dd->dispatch);
+}
+
+/*
+ * 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(struct deadline_data *dd)
+{
+        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, other_dir;
+
+        /*
+         * batches are currently reads XOR writes
+         */
+        drq = NULL;
+
+        if (dd->next_drq[READ])
+                drq = dd->next_drq[READ];
+
+        if (dd->next_drq[WRITE])
+                drq = dd->next_drq[WRITE];
+
+        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;
+                other_dir = WRITE;
+
+                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;
+                other_dir = READ;
+
+                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 struct request *deadline_next_request(request_queue_t *q)
+{
+        struct deadline_data *dd = q->elevator->elevator_data;
+        struct request *rq;
+
+        /*
+         * if there are still requests on the dispatch queue, grab the first one
+         */
+        if (!list_empty(dd->dispatch)) {
+dispatch:
+                rq = list_entry_rq(dd->dispatch->next);
+                return rq;
+        }
+
+        if (deadline_dispatch_requests(dd))
+                goto dispatch;
+
+        return NULL;
+}
+
+static void
+deadline_insert_request(request_queue_t *q, struct request *rq, int where)
+{
+        struct deadline_data *dd = q->elevator->elevator_data;
+
+        /* barriers must flush the reorder queue */
+        if (unlikely(rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)
+                        && where == ELEVATOR_INSERT_SORT))
+                where = ELEVATOR_INSERT_BACK;
+
+        switch (where) {
+                case ELEVATOR_INSERT_BACK:
+                        while (deadline_dispatch_requests(dd))
+                                ;
+                        list_add_tail(&rq->queuelist, dd->dispatch);
+                        break;
+                case ELEVATOR_INSERT_FRONT:
+                        list_add(&rq->queuelist, dd->dispatch);
+                        break;
+                case ELEVATOR_INSERT_SORT:
+                        BUG_ON(!blk_fs_request(rq));
+                        deadline_add_request(q, rq);
+                        break;
+                default:
+                        printk("%s: bad insert point %d\n", __FUNCTION__,where);
+                        return;
+        }
+}
+
+static int deadline_queue_empty(request_queue_t *q)
+{
+        struct deadline_data *dd = q->elevator->elevator_data;
+
+        if (!list_empty(&dd->fifo_list[WRITE])
+            || !list_empty(&dd->fifo_list[READ])
+            || !list_empty(dd->dispatch))
+                return 0;
+
+        return 1;
+}
+
+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(sizeof(*dd), GFP_KERNEL);
+        if (!dd)
+                return -ENOMEM;
+        memset(dd, 0, sizeof(*dd));
+
+        dd->hash = kmalloc(sizeof(struct list_head)*DL_HASH_ENTRIES,GFP_KERNEL);
+        if (!dd->hash) {
+                kfree(dd);
+                return -ENOMEM;
+        }
+
+        dd->drq_pool = mempool_create(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, drq_pool);
+        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->dispatch = &q->queue_head;
+        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);
+
+        if (drq) {
+                mempool_free(drq, dd->drq_pool);
+                rq->elevator_private = NULL;
+        }
+}
+
+static int
+deadline_set_request(request_queue_t *q, struct request *rq, int 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 0;
+
+        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 -EINVAL;
+
+        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_next_req_fn =         deadline_next_request,
+                .elevator_add_req_fn =          deadline_insert_request,
+                .elevator_remove_req_fn =       deadline_remove_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");