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-rw-r--r--block/deadline-iosched.c878
1 files changed, 878 insertions, 0 deletions
diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
new file mode 100644
index 0000000..7929471
--- /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");