Linux-2.6.12-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!
diff --git a/drivers/block/cfq-iosched.c b/drivers/block/cfq-iosched.c
new file mode 100644
index 0000000..0ef7a00
--- /dev/null
+++ b/drivers/block/cfq-iosched.c
@@ -0,0 +1,1856 @@
+/*
+ * linux/drivers/block/cfq-iosched.c
+ *
+ * CFQ, or complete fairness queueing, disk scheduler.
+ *
+ * Based on ideas from a previously unfinished io
+ * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
+ *
+ * Copyright (C) 2003 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>
+#include <linux/mempool.h>
+
+static unsigned long max_elapsed_crq;
+static unsigned long max_elapsed_dispatch;
+
+/*
+ * tunables
+ */
+static int cfq_quantum = 4; /* max queue in one round of service */
+static int cfq_queued = 8; /* minimum rq allocate limit per-queue*/
+static int cfq_service = HZ; /* period over which service is avg */
+static int cfq_fifo_expire_r = HZ / 2; /* fifo timeout for sync requests */
+static int cfq_fifo_expire_w = 5 * HZ; /* fifo timeout for async requests */
+static int cfq_fifo_rate = HZ / 8; /* fifo expiry rate */
+static int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */
+static int cfq_back_penalty = 2; /* penalty of a backwards seek */
+
+/*
+ * for the hash of cfqq inside the cfqd
+ */
+#define CFQ_QHASH_SHIFT 6
+#define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT)
+#define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash)
+
+/*
+ * for the hash of crq inside the cfqq
+ */
+#define CFQ_MHASH_SHIFT 6
+#define CFQ_MHASH_BLOCK(sec) ((sec) >> 3)
+#define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT)
+#define CFQ_MHASH_FN(sec) hash_long(CFQ_MHASH_BLOCK(sec), CFQ_MHASH_SHIFT)
+#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors)
+#define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash)
+
+#define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list)
+
+#define RQ_DATA(rq) (rq)->elevator_private
+
+/*
+ * rb-tree defines
+ */
+#define RB_NONE (2)
+#define RB_EMPTY(node) ((node)->rb_node == NULL)
+#define RB_CLEAR_COLOR(node) (node)->rb_color = RB_NONE
+#define RB_CLEAR(node) do { \
+ (node)->rb_parent = NULL; \
+ RB_CLEAR_COLOR((node)); \
+ (node)->rb_right = NULL; \
+ (node)->rb_left = NULL; \
+} while (0)
+#define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL)
+#define ON_RB(node) ((node)->rb_color != RB_NONE)
+#define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node)
+#define rq_rb_key(rq) (rq)->sector
+
+/*
+ * threshold for switching off non-tag accounting
+ */
+#define CFQ_MAX_TAG (4)
+
+/*
+ * sort key types and names
+ */
+enum {
+ CFQ_KEY_PGID,
+ CFQ_KEY_TGID,
+ CFQ_KEY_UID,
+ CFQ_KEY_GID,
+ CFQ_KEY_LAST,
+};
+
+static char *cfq_key_types[] = { "pgid", "tgid", "uid", "gid", NULL };
+
+static kmem_cache_t *crq_pool;
+static kmem_cache_t *cfq_pool;
+static kmem_cache_t *cfq_ioc_pool;
+
+struct cfq_data {
+ struct list_head rr_list;
+ struct list_head empty_list;
+
+ struct hlist_head *cfq_hash;
+ struct hlist_head *crq_hash;
+
+ /* queues on rr_list (ie they have pending requests */
+ unsigned int busy_queues;
+
+ unsigned int max_queued;
+
+ atomic_t ref;
+
+ int key_type;
+
+ mempool_t *crq_pool;
+
+ request_queue_t *queue;
+
+ sector_t last_sector;
+
+ int rq_in_driver;
+
+ /*
+ * tunables, see top of file
+ */
+ unsigned int cfq_quantum;
+ unsigned int cfq_queued;
+ unsigned int cfq_fifo_expire_r;
+ unsigned int cfq_fifo_expire_w;
+ unsigned int cfq_fifo_batch_expire;
+ unsigned int cfq_back_penalty;
+ unsigned int cfq_back_max;
+ unsigned int find_best_crq;
+
+ unsigned int cfq_tagged;
+};
+
+struct cfq_queue {
+ /* reference count */
+ atomic_t ref;
+ /* parent cfq_data */
+ struct cfq_data *cfqd;
+ /* hash of mergeable requests */
+ struct hlist_node cfq_hash;
+ /* hash key */
+ unsigned long key;
+ /* whether queue is on rr (or empty) list */
+ int on_rr;
+ /* on either rr or empty list of cfqd */
+ struct list_head cfq_list;
+ /* sorted list of pending requests */
+ struct rb_root sort_list;
+ /* if fifo isn't expired, next request to serve */
+ struct cfq_rq *next_crq;
+ /* requests queued in sort_list */
+ int queued[2];
+ /* currently allocated requests */
+ int allocated[2];
+ /* fifo list of requests in sort_list */
+ struct list_head fifo[2];
+ /* last time fifo expired */
+ unsigned long last_fifo_expire;
+
+ int key_type;
+
+ unsigned long service_start;
+ unsigned long service_used;
+
+ unsigned int max_rate;
+
+ /* number of requests that have been handed to the driver */
+ int in_flight;
+ /* number of currently allocated requests */
+ int alloc_limit[2];
+};
+
+struct cfq_rq {
+ struct rb_node rb_node;
+ sector_t rb_key;
+ struct request *request;
+ struct hlist_node hash;
+
+ struct cfq_queue *cfq_queue;
+ struct cfq_io_context *io_context;
+
+ unsigned long service_start;
+ unsigned long queue_start;
+
+ unsigned int in_flight : 1;
+ unsigned int accounted : 1;
+ unsigned int is_sync : 1;
+ unsigned int is_write : 1;
+};
+
+static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned long);
+static void cfq_dispatch_sort(request_queue_t *, struct cfq_rq *);
+static void cfq_update_next_crq(struct cfq_rq *);
+static void cfq_put_cfqd(struct cfq_data *cfqd);
+
+/*
+ * what the fairness is based on (ie how processes are grouped and
+ * differentiated)
+ */
+static inline unsigned long
+cfq_hash_key(struct cfq_data *cfqd, struct task_struct *tsk)
+{
+ /*
+ * optimize this so that ->key_type is the offset into the struct
+ */
+ switch (cfqd->key_type) {
+ case CFQ_KEY_PGID:
+ return process_group(tsk);
+ default:
+ case CFQ_KEY_TGID:
+ return tsk->tgid;
+ case CFQ_KEY_UID:
+ return tsk->uid;
+ case CFQ_KEY_GID:
+ return tsk->gid;
+ }
+}
+
+/*
+ * lots of deadline iosched dupes, can be abstracted later...
+ */
+static inline void cfq_del_crq_hash(struct cfq_rq *crq)
+{
+ hlist_del_init(&crq->hash);
+}
+
+static void cfq_remove_merge_hints(request_queue_t *q, struct cfq_rq *crq)
+{
+ cfq_del_crq_hash(crq);
+
+ if (q->last_merge == crq->request)
+ q->last_merge = NULL;
+
+ cfq_update_next_crq(crq);
+}
+
+static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq)
+{
+ const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request));
+
+ BUG_ON(!hlist_unhashed(&crq->hash));
+
+ hlist_add_head(&crq->hash, &cfqd->crq_hash[hash_idx]);
+}
+
+static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset)
+{
+ struct hlist_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)];
+ struct hlist_node *entry, *next;
+
+ hlist_for_each_safe(entry, next, hash_list) {
+ struct cfq_rq *crq = list_entry_hash(entry);
+ struct request *__rq = crq->request;
+
+ BUG_ON(hlist_unhashed(&crq->hash));
+
+ if (!rq_mergeable(__rq)) {
+ cfq_del_crq_hash(crq);
+ continue;
+ }
+
+ if (rq_hash_key(__rq) == offset)
+ return __rq;
+ }
+
+ return NULL;
+}
+
+/*
+ * Lifted from AS - choose which of crq1 and crq2 that is best served now.
+ * We choose the request that is closest to the head right now. Distance
+ * behind the head are penalized and only allowed to a certain extent.
+ */
+static struct cfq_rq *
+cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2)
+{
+ sector_t last, s1, s2, d1 = 0, d2 = 0;
+ int r1_wrap = 0, r2_wrap = 0; /* requests are behind the disk head */
+ unsigned long back_max;
+
+ if (crq1 == NULL || crq1 == crq2)
+ return crq2;
+ if (crq2 == NULL)
+ return crq1;
+
+ s1 = crq1->request->sector;
+ s2 = crq2->request->sector;
+
+ last = cfqd->last_sector;
+
+#if 0
+ if (!list_empty(&cfqd->queue->queue_head)) {
+ struct list_head *entry = &cfqd->queue->queue_head;
+ unsigned long distance = ~0UL;
+ struct request *rq;
+
+ while ((entry = entry->prev) != &cfqd->queue->queue_head) {
+ rq = list_entry_rq(entry);
+
+ if (blk_barrier_rq(rq))
+ break;
+
+ if (distance < abs(s1 - rq->sector + rq->nr_sectors)) {
+ distance = abs(s1 - rq->sector +rq->nr_sectors);
+ last = rq->sector + rq->nr_sectors;
+ }
+ if (distance < abs(s2 - rq->sector + rq->nr_sectors)) {
+ distance = abs(s2 - rq->sector +rq->nr_sectors);
+ last = rq->sector + rq->nr_sectors;
+ }
+ }
+ }
+#endif
+
+ /*
+ * by definition, 1KiB is 2 sectors
+ */
+ back_max = cfqd->cfq_back_max * 2;
+
+ /*
+ * Strict one way elevator _except_ in the case where we allow
+ * short backward seeks which are biased as twice the cost of a
+ * similar forward seek.
+ */
+ if (s1 >= last)
+ d1 = s1 - last;
+ else if (s1 + back_max >= last)
+ d1 = (last - s1) * cfqd->cfq_back_penalty;
+ else
+ r1_wrap = 1;
+
+ if (s2 >= last)
+ d2 = s2 - last;
+ else if (s2 + back_max >= last)
+ d2 = (last - s2) * cfqd->cfq_back_penalty;
+ else
+ r2_wrap = 1;
+
+ /* Found required data */
+ if (!r1_wrap && r2_wrap)
+ return crq1;
+ else if (!r2_wrap && r1_wrap)
+ return crq2;
+ else if (r1_wrap && r2_wrap) {
+ /* both behind the head */
+ if (s1 <= s2)
+ return crq1;
+ else
+ return crq2;
+ }
+
+ /* Both requests in front of the head */
+ if (d1 < d2)
+ return crq1;
+ else if (d2 < d1)
+ return crq2;
+ else {
+ if (s1 >= s2)
+ return crq1;
+ else
+ return crq2;
+ }
+}
+
+/*
+ * would be nice to take fifo expire time into account as well
+ */
+static struct cfq_rq *
+cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
+ struct cfq_rq *last)
+{
+ struct cfq_rq *crq_next = NULL, *crq_prev = NULL;
+ struct rb_node *rbnext, *rbprev;
+
+ if (!ON_RB(&last->rb_node))
+ return NULL;
+
+ if ((rbnext = rb_next(&last->rb_node)) == NULL)
+ rbnext = rb_first(&cfqq->sort_list);
+
+ rbprev = rb_prev(&last->rb_node);
+
+ if (rbprev)
+ crq_prev = rb_entry_crq(rbprev);
+ if (rbnext)
+ crq_next = rb_entry_crq(rbnext);
+
+ return cfq_choose_req(cfqd, crq_next, crq_prev);
+}
+
+static void cfq_update_next_crq(struct cfq_rq *crq)
+{
+ struct cfq_queue *cfqq = crq->cfq_queue;
+
+ if (cfqq->next_crq == crq)
+ cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq);
+}
+
+static int cfq_check_sort_rr_list(struct cfq_queue *cfqq)
+{
+ struct list_head *head = &cfqq->cfqd->rr_list;
+ struct list_head *next, *prev;
+
+ /*
+ * list might still be ordered
+ */
+ next = cfqq->cfq_list.next;
+ if (next != head) {
+ struct cfq_queue *cnext = list_entry_cfqq(next);
+
+ if (cfqq->service_used > cnext->service_used)
+ return 1;
+ }
+
+ prev = cfqq->cfq_list.prev;
+ if (prev != head) {
+ struct cfq_queue *cprev = list_entry_cfqq(prev);
+
+ if (cfqq->service_used < cprev->service_used)
+ return 1;
+ }
+
+ return 0;
+}
+
+static void cfq_sort_rr_list(struct cfq_queue *cfqq, int new_queue)
+{
+ struct list_head *entry = &cfqq->cfqd->rr_list;
+
+ if (!cfqq->on_rr)
+ return;
+ if (!new_queue && !cfq_check_sort_rr_list(cfqq))
+ return;
+
+ list_del(&cfqq->cfq_list);
+
+ /*
+ * sort by our mean service_used, sub-sort by in-flight requests
+ */
+ while ((entry = entry->prev) != &cfqq->cfqd->rr_list) {
+ struct cfq_queue *__cfqq = list_entry_cfqq(entry);
+
+ if (cfqq->service_used > __cfqq->service_used)
+ break;
+ else if (cfqq->service_used == __cfqq->service_used) {
+ struct list_head *prv;
+
+ while ((prv = entry->prev) != &cfqq->cfqd->rr_list) {
+ __cfqq = list_entry_cfqq(prv);
+
+ WARN_ON(__cfqq->service_used > cfqq->service_used);
+ if (cfqq->service_used != __cfqq->service_used)
+ break;
+ if (cfqq->in_flight > __cfqq->in_flight)
+ break;
+
+ entry = prv;
+ }
+ }
+ }
+
+ list_add(&cfqq->cfq_list, entry);
+}
+
+/*
+ * add to busy list of queues for service, trying to be fair in ordering
+ * the pending list according to requests serviced
+ */
+static inline void
+cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ /*
+ * it's currently on the empty list
+ */
+ cfqq->on_rr = 1;
+ cfqd->busy_queues++;
+
+ if (time_after(jiffies, cfqq->service_start + cfq_service))
+ cfqq->service_used >>= 3;
+
+ cfq_sort_rr_list(cfqq, 1);
+}
+
+static inline void
+cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ list_move(&cfqq->cfq_list, &cfqd->empty_list);
+ cfqq->on_rr = 0;
+
+ BUG_ON(!cfqd->busy_queues);
+ cfqd->busy_queues--;
+}
+
+/*
+ * rb tree support functions
+ */
+static inline void cfq_del_crq_rb(struct cfq_rq *crq)
+{
+ struct cfq_queue *cfqq = crq->cfq_queue;
+
+ if (ON_RB(&crq->rb_node)) {
+ struct cfq_data *cfqd = cfqq->cfqd;
+
+ BUG_ON(!cfqq->queued[crq->is_sync]);
+
+ cfq_update_next_crq(crq);
+
+ cfqq->queued[crq->is_sync]--;
+ rb_erase(&crq->rb_node, &cfqq->sort_list);
+ RB_CLEAR_COLOR(&crq->rb_node);
+
+ if (RB_EMPTY(&cfqq->sort_list) && cfqq->on_rr)
+ cfq_del_cfqq_rr(cfqd, cfqq);
+ }
+}
+
+static struct cfq_rq *
+__cfq_add_crq_rb(struct cfq_rq *crq)
+{
+ struct rb_node **p = &crq->cfq_queue->sort_list.rb_node;
+ struct rb_node *parent = NULL;
+ struct cfq_rq *__crq;
+
+ while (*p) {
+ parent = *p;
+ __crq = rb_entry_crq(parent);
+
+ if (crq->rb_key < __crq->rb_key)
+ p = &(*p)->rb_left;
+ else if (crq->rb_key > __crq->rb_key)
+ p = &(*p)->rb_right;
+ else
+ return __crq;
+ }
+
+ rb_link_node(&crq->rb_node, parent, p);
+ return NULL;
+}
+
+static void cfq_add_crq_rb(struct cfq_rq *crq)
+{
+ struct cfq_queue *cfqq = crq->cfq_queue;
+ struct cfq_data *cfqd = cfqq->cfqd;
+ struct request *rq = crq->request;
+ struct cfq_rq *__alias;
+
+ crq->rb_key = rq_rb_key(rq);
+ cfqq->queued[crq->is_sync]++;
+
+ /*
+ * looks a little odd, but the first insert might return an alias.
+ * if that happens, put the alias on the dispatch list
+ */
+ while ((__alias = __cfq_add_crq_rb(crq)) != NULL)
+ cfq_dispatch_sort(cfqd->queue, __alias);
+
+ rb_insert_color(&crq->rb_node, &cfqq->sort_list);
+
+ if (!cfqq->on_rr)
+ cfq_add_cfqq_rr(cfqd, cfqq);
+
+ /*
+ * check if this request is a better next-serve candidate
+ */
+ cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq);
+}
+
+static inline void
+cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq)
+{
+ if (ON_RB(&crq->rb_node)) {
+ rb_erase(&crq->rb_node, &cfqq->sort_list);
+ cfqq->queued[crq->is_sync]--;
+ }
+
+ cfq_add_crq_rb(crq);
+}
+
+static struct request *
+cfq_find_rq_rb(struct cfq_data *cfqd, sector_t sector)
+{
+ const unsigned long key = cfq_hash_key(cfqd, current);
+ struct cfq_queue *cfqq = cfq_find_cfq_hash(cfqd, key);
+ struct rb_node *n;
+
+ if (!cfqq)
+ goto out;
+
+ n = cfqq->sort_list.rb_node;
+ while (n) {
+ struct cfq_rq *crq = rb_entry_crq(n);
+
+ if (sector < crq->rb_key)
+ n = n->rb_left;
+ else if (sector > crq->rb_key)
+ n = n->rb_right;
+ else
+ return crq->request;
+ }
+
+out:
+ return NULL;
+}
+
+static void cfq_deactivate_request(request_queue_t *q, struct request *rq)
+{
+ struct cfq_rq *crq = RQ_DATA(rq);
+
+ if (crq) {
+ struct cfq_queue *cfqq = crq->cfq_queue;
+
+ if (cfqq->cfqd->cfq_tagged) {
+ cfqq->service_used--;
+ cfq_sort_rr_list(cfqq, 0);
+ }
+
+ if (crq->accounted) {
+ crq->accounted = 0;
+ cfqq->cfqd->rq_in_driver--;
+ }
+ }
+}
+
+/*
+ * make sure the service time gets corrected on reissue of this request
+ */
+static void cfq_requeue_request(request_queue_t *q, struct request *rq)
+{
+ cfq_deactivate_request(q, rq);
+ list_add(&rq->queuelist, &q->queue_head);
+}
+
+static void cfq_remove_request(request_queue_t *q, struct request *rq)
+{
+ struct cfq_rq *crq = RQ_DATA(rq);
+
+ if (crq) {
+ cfq_remove_merge_hints(q, crq);
+ list_del_init(&rq->queuelist);
+
+ if (crq->cfq_queue)
+ cfq_del_crq_rb(crq);
+ }
+}
+
+static int
+cfq_merge(request_queue_t *q, struct request **req, struct bio *bio)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct request *__rq;
+ int ret;
+
+ ret = elv_try_last_merge(q, bio);
+ if (ret != ELEVATOR_NO_MERGE) {
+ __rq = q->last_merge;
+ goto out_insert;
+ }
+
+ __rq = cfq_find_rq_hash(cfqd, 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;
+ }
+ }
+
+ __rq = cfq_find_rq_rb(cfqd, bio->bi_sector + bio_sectors(bio));
+ if (__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:
+ *req = __rq;
+ return ret;
+}
+
+static void cfq_merged_request(request_queue_t *q, struct request *req)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct cfq_rq *crq = RQ_DATA(req);
+
+ cfq_del_crq_hash(crq);
+ cfq_add_crq_hash(cfqd, crq);
+
+ if (ON_RB(&crq->rb_node) && (rq_rb_key(req) != crq->rb_key)) {
+ struct cfq_queue *cfqq = crq->cfq_queue;
+
+ cfq_update_next_crq(crq);
+ cfq_reposition_crq_rb(cfqq, crq);
+ }
+
+ q->last_merge = req;
+}
+
+static void
+cfq_merged_requests(request_queue_t *q, struct request *rq,
+ struct request *next)
+{
+ struct cfq_rq *crq = RQ_DATA(rq);
+ struct cfq_rq *cnext = RQ_DATA(next);
+
+ cfq_merged_request(q, rq);
+
+ if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist)) {
+ if (time_before(cnext->queue_start, crq->queue_start)) {
+ list_move(&rq->queuelist, &next->queuelist);
+ crq->queue_start = cnext->queue_start;
+ }
+ }
+
+ cfq_update_next_crq(cnext);
+ cfq_remove_request(q, next);
+}
+
+/*
+ * we dispatch cfqd->cfq_quantum requests in total from the rr_list queues,
+ * this function sector sorts the selected request to minimize seeks. we start
+ * at cfqd->last_sector, not 0.
+ */
+static void cfq_dispatch_sort(request_queue_t *q, struct cfq_rq *crq)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct cfq_queue *cfqq = crq->cfq_queue;
+ struct list_head *head = &q->queue_head, *entry = head;
+ struct request *__rq;
+ sector_t last;
+
+ cfq_del_crq_rb(crq);
+ cfq_remove_merge_hints(q, crq);
+ list_del(&crq->request->queuelist);
+
+ last = cfqd->last_sector;
+ while ((entry = entry->prev) != head) {
+ __rq = list_entry_rq(entry);
+
+ if (blk_barrier_rq(crq->request))
+ break;
+ if (!blk_fs_request(crq->request))
+ break;
+
+ if (crq->request->sector > __rq->sector)
+ break;
+ if (__rq->sector > last && crq->request->sector < last) {
+ last = crq->request->sector;
+ break;
+ }
+ }
+
+ cfqd->last_sector = last;
+ crq->in_flight = 1;
+ cfqq->in_flight++;
+ list_add(&crq->request->queuelist, entry);
+}
+
+/*
+ * return expired entry, or NULL to just start from scratch in rbtree
+ */
+static inline struct cfq_rq *cfq_check_fifo(struct cfq_queue *cfqq)
+{
+ struct cfq_data *cfqd = cfqq->cfqd;
+ const int reads = !list_empty(&cfqq->fifo[0]);
+ const int writes = !list_empty(&cfqq->fifo[1]);
+ unsigned long now = jiffies;
+ struct cfq_rq *crq;
+
+ if (time_before(now, cfqq->last_fifo_expire + cfqd->cfq_fifo_batch_expire))
+ return NULL;
+
+ crq = RQ_DATA(list_entry(cfqq->fifo[0].next, struct request, queuelist));
+ if (reads && time_after(now, crq->queue_start + cfqd->cfq_fifo_expire_r)) {
+ cfqq->last_fifo_expire = now;
+ return crq;
+ }
+
+ crq = RQ_DATA(list_entry(cfqq->fifo[1].next, struct request, queuelist));
+ if (writes && time_after(now, crq->queue_start + cfqd->cfq_fifo_expire_w)) {
+ cfqq->last_fifo_expire = now;
+ return crq;
+ }
+
+ return NULL;
+}
+
+/*
+ * dispatch a single request from given queue
+ */
+static inline void
+cfq_dispatch_request(request_queue_t *q, struct cfq_data *cfqd,
+ struct cfq_queue *cfqq)
+{
+ struct cfq_rq *crq;
+
+ /*
+ * follow expired path, else get first next available
+ */
+ if ((crq = cfq_check_fifo(cfqq)) == NULL) {
+ if (cfqd->find_best_crq)
+ crq = cfqq->next_crq;
+ else
+ crq = rb_entry_crq(rb_first(&cfqq->sort_list));
+ }
+
+ cfqd->last_sector = crq->request->sector + crq->request->nr_sectors;
+
+ /*
+ * finally, insert request into driver list
+ */
+ cfq_dispatch_sort(q, crq);
+}
+
+static int cfq_dispatch_requests(request_queue_t *q, int max_dispatch)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct cfq_queue *cfqq;
+ struct list_head *entry, *tmp;
+ int queued, busy_queues, first_round;
+
+ if (list_empty(&cfqd->rr_list))
+ return 0;
+
+ queued = 0;
+ first_round = 1;
+restart:
+ busy_queues = 0;
+ list_for_each_safe(entry, tmp, &cfqd->rr_list) {
+ cfqq = list_entry_cfqq(entry);
+
+ BUG_ON(RB_EMPTY(&cfqq->sort_list));
+
+ /*
+ * first round of queueing, only select from queues that
+ * don't already have io in-flight
+ */
+ if (first_round && cfqq->in_flight)
+ continue;
+
+ cfq_dispatch_request(q, cfqd, cfqq);
+
+ if (!RB_EMPTY(&cfqq->sort_list))
+ busy_queues++;
+
+ queued++;
+ }
+
+ if ((queued < max_dispatch) && (busy_queues || first_round)) {
+ first_round = 0;
+ goto restart;
+ }
+
+ return queued;
+}
+
+static inline void cfq_account_dispatch(struct cfq_rq *crq)
+{
+ struct cfq_queue *cfqq = crq->cfq_queue;
+ struct cfq_data *cfqd = cfqq->cfqd;
+ unsigned long now, elapsed;
+
+ if (!blk_fs_request(crq->request))
+ return;
+
+ /*
+ * accounted bit is necessary since some drivers will call
+ * elv_next_request() many times for the same request (eg ide)
+ */
+ if (crq->accounted)
+ return;
+
+ now = jiffies;
+ if (cfqq->service_start == ~0UL)
+ cfqq->service_start = now;
+
+ /*
+ * on drives with tagged command queueing, command turn-around time
+ * doesn't necessarily reflect the time spent processing this very
+ * command inside the drive. so do the accounting differently there,
+ * by just sorting on the number of requests
+ */
+ if (cfqd->cfq_tagged) {
+ if (time_after(now, cfqq->service_start + cfq_service)) {
+ cfqq->service_start = now;
+ cfqq->service_used /= 10;
+ }
+
+ cfqq->service_used++;
+ cfq_sort_rr_list(cfqq, 0);
+ }
+
+ elapsed = now - crq->queue_start;
+ if (elapsed > max_elapsed_dispatch)
+ max_elapsed_dispatch = elapsed;
+
+ crq->accounted = 1;
+ crq->service_start = now;
+
+ if (++cfqd->rq_in_driver >= CFQ_MAX_TAG && !cfqd->cfq_tagged) {
+ cfqq->cfqd->cfq_tagged = 1;
+ printk("cfq: depth %d reached, tagging now on\n", CFQ_MAX_TAG);
+ }
+}
+
+static inline void
+cfq_account_completion(struct cfq_queue *cfqq, struct cfq_rq *crq)
+{
+ struct cfq_data *cfqd = cfqq->cfqd;
+
+ if (!crq->accounted)
+ return;
+
+ WARN_ON(!cfqd->rq_in_driver);
+ cfqd->rq_in_driver--;
+
+ if (!cfqd->cfq_tagged) {
+ unsigned long now = jiffies;
+ unsigned long duration = now - crq->service_start;
+
+ if (time_after(now, cfqq->service_start + cfq_service)) {
+ cfqq->service_start = now;
+ cfqq->service_used >>= 3;
+ }
+
+ cfqq->service_used += duration;
+ cfq_sort_rr_list(cfqq, 0);
+
+ if (duration > max_elapsed_crq)
+ max_elapsed_crq = duration;
+ }
+}
+
+static struct request *cfq_next_request(request_queue_t *q)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct request *rq;
+
+ if (!list_empty(&q->queue_head)) {
+ struct cfq_rq *crq;
+dispatch:
+ rq = list_entry_rq(q->queue_head.next);
+
+ if ((crq = RQ_DATA(rq)) != NULL) {
+ cfq_remove_merge_hints(q, crq);
+ cfq_account_dispatch(crq);
+ }
+
+ return rq;
+ }
+
+ if (cfq_dispatch_requests(q, cfqd->cfq_quantum))
+ goto dispatch;
+
+ return NULL;
+}
+
+/*
+ * task holds one reference to the queue, dropped when task exits. each crq
+ * in-flight on this queue also holds a reference, dropped when crq is freed.
+ *
+ * queue lock must be held here.
+ */
+static void cfq_put_queue(struct cfq_queue *cfqq)
+{
+ BUG_ON(!atomic_read(&cfqq->ref));
+
+ if (!atomic_dec_and_test(&cfqq->ref))
+ return;
+
+ BUG_ON(rb_first(&cfqq->sort_list));
+ BUG_ON(cfqq->on_rr);
+
+ cfq_put_cfqd(cfqq->cfqd);
+
+ /*
+ * it's on the empty list and still hashed
+ */
+ list_del(&cfqq->cfq_list);
+ hlist_del(&cfqq->cfq_hash);
+ kmem_cache_free(cfq_pool, cfqq);
+}
+
+static inline struct cfq_queue *
+__cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned long key, const int hashval)
+{
+ struct hlist_head *hash_list = &cfqd->cfq_hash[hashval];
+ struct hlist_node *entry, *next;
+
+ hlist_for_each_safe(entry, next, hash_list) {
+ struct cfq_queue *__cfqq = list_entry_qhash(entry);
+
+ if (__cfqq->key == key)
+ return __cfqq;
+ }
+
+ return NULL;
+}
+
+static struct cfq_queue *
+cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned long key)
+{
+ return __cfq_find_cfq_hash(cfqd, key, hash_long(key, CFQ_QHASH_SHIFT));
+}
+
+static inline void
+cfq_rehash_cfqq(struct cfq_data *cfqd, struct cfq_queue **cfqq,
+ struct cfq_io_context *cic)
+{
+ unsigned long hashkey = cfq_hash_key(cfqd, current);
+ unsigned long hashval = hash_long(hashkey, CFQ_QHASH_SHIFT);
+ struct cfq_queue *__cfqq;
+ unsigned long flags;
+
+ spin_lock_irqsave(cfqd->queue->queue_lock, flags);
+
+ hlist_del(&(*cfqq)->cfq_hash);
+
+ __cfqq = __cfq_find_cfq_hash(cfqd, hashkey, hashval);
+ if (!__cfqq || __cfqq == *cfqq) {
+ __cfqq = *cfqq;
+ hlist_add_head(&__cfqq->cfq_hash, &cfqd->cfq_hash[hashval]);
+ __cfqq->key_type = cfqd->key_type;
+ } else {
+ atomic_inc(&__cfqq->ref);
+ cic->cfqq = __cfqq;
+ cfq_put_queue(*cfqq);
+ *cfqq = __cfqq;
+ }
+
+ cic->cfqq = __cfqq;
+ spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
+}
+
+static void cfq_free_io_context(struct cfq_io_context *cic)
+{
+ kmem_cache_free(cfq_ioc_pool, cic);
+}
+
+/*
+ * locking hierarchy is: io_context lock -> queue locks
+ */
+static void cfq_exit_io_context(struct cfq_io_context *cic)
+{
+ struct cfq_queue *cfqq = cic->cfqq;
+ struct list_head *entry = &cic->list;
+ request_queue_t *q;
+ unsigned long flags;
+
+ /*
+ * put the reference this task is holding to the various queues
+ */
+ spin_lock_irqsave(&cic->ioc->lock, flags);
+ while ((entry = cic->list.next) != &cic->list) {
+ struct cfq_io_context *__cic;
+
+ __cic = list_entry(entry, struct cfq_io_context, list);
+ list_del(entry);
+
+ q = __cic->cfqq->cfqd->queue;
+ spin_lock(q->queue_lock);
+ cfq_put_queue(__cic->cfqq);
+ spin_unlock(q->queue_lock);
+ }
+
+ q = cfqq->cfqd->queue;
+ spin_lock(q->queue_lock);
+ cfq_put_queue(cfqq);
+ spin_unlock(q->queue_lock);
+
+ cic->cfqq = NULL;
+ spin_unlock_irqrestore(&cic->ioc->lock, flags);
+}
+
+static struct cfq_io_context *cfq_alloc_io_context(int gfp_flags)
+{
+ struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_flags);
+
+ if (cic) {
+ cic->dtor = cfq_free_io_context;
+ cic->exit = cfq_exit_io_context;
+ INIT_LIST_HEAD(&cic->list);
+ cic->cfqq = NULL;
+ }
+
+ return cic;
+}
+
+/*
+ * Setup general io context and cfq io context. There can be several cfq
+ * io contexts per general io context, if this process is doing io to more
+ * than one device managed by cfq. Note that caller is holding a reference to
+ * cfqq, so we don't need to worry about it disappearing
+ */
+static struct cfq_io_context *
+cfq_get_io_context(struct cfq_queue **cfqq, int gfp_flags)
+{
+ struct cfq_data *cfqd = (*cfqq)->cfqd;
+ struct cfq_queue *__cfqq = *cfqq;
+ struct cfq_io_context *cic;
+ struct io_context *ioc;
+
+ might_sleep_if(gfp_flags & __GFP_WAIT);
+
+ ioc = get_io_context(gfp_flags);
+ if (!ioc)
+ return NULL;
+
+ if ((cic = ioc->cic) == NULL) {
+ cic = cfq_alloc_io_context(gfp_flags);
+
+ if (cic == NULL)
+ goto err;
+
+ ioc->cic = cic;
+ cic->ioc = ioc;
+ cic->cfqq = __cfqq;
+ atomic_inc(&__cfqq->ref);
+ } else {
+ struct cfq_io_context *__cic;
+ unsigned long flags;
+
+ /*
+ * since the first cic on the list is actually the head
+ * itself, need to check this here or we'll duplicate an
+ * cic per ioc for no reason
+ */
+ if (cic->cfqq == __cfqq)
+ goto out;
+
+ /*
+ * cic exists, check if we already are there. linear search
+ * should be ok here, the list will usually not be more than
+ * 1 or a few entries long
+ */
+ spin_lock_irqsave(&ioc->lock, flags);
+ list_for_each_entry(__cic, &cic->list, list) {
+ /*
+ * this process is already holding a reference to
+ * this queue, so no need to get one more
+ */
+ if (__cic->cfqq == __cfqq) {
+ cic = __cic;
+ spin_unlock_irqrestore(&ioc->lock, flags);
+ goto out;
+ }
+ }
+ spin_unlock_irqrestore(&ioc->lock, flags);
+
+ /*
+ * nope, process doesn't have a cic assoicated with this
+ * cfqq yet. get a new one and add to list
+ */
+ __cic = cfq_alloc_io_context(gfp_flags);
+ if (__cic == NULL)
+ goto err;
+
+ __cic->ioc = ioc;
+ __cic->cfqq = __cfqq;
+ atomic_inc(&__cfqq->ref);
+ spin_lock_irqsave(&ioc->lock, flags);
+ list_add(&__cic->list, &cic->list);
+ spin_unlock_irqrestore(&ioc->lock, flags);
+
+ cic = __cic;
+ *cfqq = __cfqq;
+ }
+
+out:
+ /*
+ * if key_type has been changed on the fly, we lazily rehash
+ * each queue at lookup time
+ */
+ if ((*cfqq)->key_type != cfqd->key_type)
+ cfq_rehash_cfqq(cfqd, cfqq, cic);
+
+ return cic;
+err:
+ put_io_context(ioc);
+ return NULL;
+}
+
+static struct cfq_queue *
+__cfq_get_queue(struct cfq_data *cfqd, unsigned long key, int gfp_mask)
+{
+ const int hashval = hash_long(key, CFQ_QHASH_SHIFT);
+ struct cfq_queue *cfqq, *new_cfqq = NULL;
+
+retry:
+ cfqq = __cfq_find_cfq_hash(cfqd, key, hashval);
+
+ if (!cfqq) {
+ if (new_cfqq) {
+ cfqq = new_cfqq;
+ new_cfqq = NULL;
+ } else if (gfp_mask & __GFP_WAIT) {
+ spin_unlock_irq(cfqd->queue->queue_lock);
+ new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask);
+ spin_lock_irq(cfqd->queue->queue_lock);
+ goto retry;
+ } else
+ goto out;
+
+ memset(cfqq, 0, sizeof(*cfqq));
+
+ INIT_HLIST_NODE(&cfqq->cfq_hash);
+ INIT_LIST_HEAD(&cfqq->cfq_list);
+ RB_CLEAR_ROOT(&cfqq->sort_list);
+ INIT_LIST_HEAD(&cfqq->fifo[0]);
+ INIT_LIST_HEAD(&cfqq->fifo[1]);
+
+ cfqq->key = key;
+ hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]);
+ atomic_set(&cfqq->ref, 0);
+ cfqq->cfqd = cfqd;
+ atomic_inc(&cfqd->ref);
+ cfqq->key_type = cfqd->key_type;
+ cfqq->service_start = ~0UL;
+ }
+
+ if (new_cfqq)
+ kmem_cache_free(cfq_pool, new_cfqq);
+
+ atomic_inc(&cfqq->ref);
+out:
+ WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq);
+ return cfqq;
+}
+
+static void cfq_enqueue(struct cfq_data *cfqd, struct cfq_rq *crq)
+{
+ crq->is_sync = 0;
+ if (rq_data_dir(crq->request) == READ || current->flags & PF_SYNCWRITE)
+ crq->is_sync = 1;
+
+ cfq_add_crq_rb(crq);
+ crq->queue_start = jiffies;
+
+ list_add_tail(&crq->request->queuelist, &crq->cfq_queue->fifo[crq->is_sync]);
+}
+
+static void
+cfq_insert_request(request_queue_t *q, struct request *rq, int where)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct cfq_rq *crq = RQ_DATA(rq);
+
+ switch (where) {
+ case ELEVATOR_INSERT_BACK:
+ while (cfq_dispatch_requests(q, cfqd->cfq_quantum))
+ ;
+ list_add_tail(&rq->queuelist, &q->queue_head);
+ break;
+ case ELEVATOR_INSERT_FRONT:
+ list_add(&rq->queuelist, &q->queue_head);
+ break;
+ case ELEVATOR_INSERT_SORT:
+ BUG_ON(!blk_fs_request(rq));
+ cfq_enqueue(cfqd, crq);
+ break;
+ default:
+ printk("%s: bad insert point %d\n", __FUNCTION__,where);
+ return;
+ }
+
+ if (rq_mergeable(rq)) {
+ cfq_add_crq_hash(cfqd, crq);
+
+ if (!q->last_merge)
+ q->last_merge = rq;
+ }
+}
+
+static int cfq_queue_empty(request_queue_t *q)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+
+ return list_empty(&q->queue_head) && list_empty(&cfqd->rr_list);
+}
+
+static void cfq_completed_request(request_queue_t *q, struct request *rq)
+{
+ struct cfq_rq *crq = RQ_DATA(rq);
+ struct cfq_queue *cfqq;
+
+ if (unlikely(!blk_fs_request(rq)))
+ return;
+
+ cfqq = crq->cfq_queue;
+
+ if (crq->in_flight) {
+ WARN_ON(!cfqq->in_flight);
+ cfqq->in_flight--;
+ }
+
+ cfq_account_completion(cfqq, crq);
+}
+
+static struct request *
+cfq_former_request(request_queue_t *q, struct request *rq)
+{
+ struct cfq_rq *crq = RQ_DATA(rq);
+ struct rb_node *rbprev = rb_prev(&crq->rb_node);
+
+ if (rbprev)
+ return rb_entry_crq(rbprev)->request;
+
+ return NULL;
+}
+
+static struct request *
+cfq_latter_request(request_queue_t *q, struct request *rq)
+{
+ struct cfq_rq *crq = RQ_DATA(rq);
+ struct rb_node *rbnext = rb_next(&crq->rb_node);
+
+ if (rbnext)
+ return rb_entry_crq(rbnext)->request;
+
+ return NULL;
+}
+
+static int cfq_may_queue(request_queue_t *q, int rw)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct cfq_queue *cfqq;
+ int ret = ELV_MQUEUE_MAY;
+
+ if (current->flags & PF_MEMALLOC)
+ return ELV_MQUEUE_MAY;
+
+ cfqq = cfq_find_cfq_hash(cfqd, cfq_hash_key(cfqd, current));
+ if (cfqq) {
+ int limit = cfqd->max_queued;
+
+ if (cfqq->allocated[rw] < cfqd->cfq_queued)
+ return ELV_MQUEUE_MUST;
+
+ if (cfqd->busy_queues)
+ limit = q->nr_requests / cfqd->busy_queues;
+
+ if (limit < cfqd->cfq_queued)
+ limit = cfqd->cfq_queued;
+ else if (limit > cfqd->max_queued)
+ limit = cfqd->max_queued;
+
+ if (cfqq->allocated[rw] >= limit) {
+ if (limit > cfqq->alloc_limit[rw])
+ cfqq->alloc_limit[rw] = limit;
+
+ ret = ELV_MQUEUE_NO;
+ }
+ }
+
+ return ret;
+}
+
+static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq)
+{
+ struct request_list *rl = &q->rq;
+ const int write = waitqueue_active(&rl->wait[WRITE]);
+ const int read = waitqueue_active(&rl->wait[READ]);
+
+ if (read && cfqq->allocated[READ] < cfqq->alloc_limit[READ])
+ wake_up(&rl->wait[READ]);
+ if (write && cfqq->allocated[WRITE] < cfqq->alloc_limit[WRITE])
+ wake_up(&rl->wait[WRITE]);
+}
+
+/*
+ * queue lock held here
+ */
+static void cfq_put_request(request_queue_t *q, struct request *rq)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct cfq_rq *crq = RQ_DATA(rq);
+
+ if (crq) {
+ struct cfq_queue *cfqq = crq->cfq_queue;
+
+ BUG_ON(q->last_merge == rq);
+ BUG_ON(!hlist_unhashed(&crq->hash));
+
+ if (crq->io_context)
+ put_io_context(crq->io_context->ioc);
+
+ BUG_ON(!cfqq->allocated[crq->is_write]);
+ cfqq->allocated[crq->is_write]--;
+
+ mempool_free(crq, cfqd->crq_pool);
+ rq->elevator_private = NULL;
+
+ smp_mb();
+ cfq_check_waiters(q, cfqq);
+ cfq_put_queue(cfqq);
+ }
+}
+
+/*
+ * Allocate cfq data structures associated with this request. A queue and
+ */
+static int cfq_set_request(request_queue_t *q, struct request *rq, int gfp_mask)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct cfq_io_context *cic;
+ const int rw = rq_data_dir(rq);
+ struct cfq_queue *cfqq, *saved_cfqq;
+ struct cfq_rq *crq;
+ unsigned long flags;
+
+ might_sleep_if(gfp_mask & __GFP_WAIT);
+
+ spin_lock_irqsave(q->queue_lock, flags);
+
+ cfqq = __cfq_get_queue(cfqd, cfq_hash_key(cfqd, current), gfp_mask);
+ if (!cfqq)
+ goto out_lock;
+
+repeat:
+ if (cfqq->allocated[rw] >= cfqd->max_queued)
+ goto out_lock;
+
+ cfqq->allocated[rw]++;
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ /*
+ * if hashing type has changed, the cfq_queue might change here.
+ */
+ saved_cfqq = cfqq;
+ cic = cfq_get_io_context(&cfqq, gfp_mask);
+ if (!cic)
+ goto err;
+
+ /*
+ * repeat allocation checks on queue change
+ */
+ if (unlikely(saved_cfqq != cfqq)) {
+ spin_lock_irqsave(q->queue_lock, flags);
+ saved_cfqq->allocated[rw]--;
+ goto repeat;
+ }
+
+ crq = mempool_alloc(cfqd->crq_pool, gfp_mask);
+ if (crq) {
+ RB_CLEAR(&crq->rb_node);
+ crq->rb_key = 0;
+ crq->request = rq;
+ INIT_HLIST_NODE(&crq->hash);
+ crq->cfq_queue = cfqq;
+ crq->io_context = cic;
+ crq->service_start = crq->queue_start = 0;
+ crq->in_flight = crq->accounted = crq->is_sync = 0;
+ crq->is_write = rw;
+ rq->elevator_private = crq;
+ cfqq->alloc_limit[rw] = 0;
+ return 0;
+ }
+
+ put_io_context(cic->ioc);
+err:
+ spin_lock_irqsave(q->queue_lock, flags);
+ cfqq->allocated[rw]--;
+ cfq_put_queue(cfqq);
+out_lock:
+ spin_unlock_irqrestore(q->queue_lock, flags);
+ return 1;
+}
+
+static void cfq_put_cfqd(struct cfq_data *cfqd)
+{
+ request_queue_t *q = cfqd->queue;
+
+ if (!atomic_dec_and_test(&cfqd->ref))
+ return;
+
+ blk_put_queue(q);
+
+ mempool_destroy(cfqd->crq_pool);
+ kfree(cfqd->crq_hash);
+ kfree(cfqd->cfq_hash);
+ kfree(cfqd);
+}
+
+static void cfq_exit_queue(elevator_t *e)
+{
+ cfq_put_cfqd(e->elevator_data);
+}
+
+static int cfq_init_queue(request_queue_t *q, elevator_t *e)
+{
+ struct cfq_data *cfqd;
+ int i;
+
+ cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL);
+ if (!cfqd)
+ return -ENOMEM;
+
+ memset(cfqd, 0, sizeof(*cfqd));
+ INIT_LIST_HEAD(&cfqd->rr_list);
+ INIT_LIST_HEAD(&cfqd->empty_list);
+
+ cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL);
+ if (!cfqd->crq_hash)
+ goto out_crqhash;
+
+ cfqd->cfq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL);
+ if (!cfqd->cfq_hash)
+ goto out_cfqhash;
+
+ cfqd->crq_pool = mempool_create(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, crq_pool);
+ if (!cfqd->crq_pool)
+ goto out_crqpool;
+
+ for (i = 0; i < CFQ_MHASH_ENTRIES; i++)
+ INIT_HLIST_HEAD(&cfqd->crq_hash[i]);
+ for (i = 0; i < CFQ_QHASH_ENTRIES; i++)
+ INIT_HLIST_HEAD(&cfqd->cfq_hash[i]);
+
+ e->elevator_data = cfqd;
+
+ cfqd->queue = q;
+ atomic_inc(&q->refcnt);
+
+ /*
+ * just set it to some high value, we want anyone to be able to queue
+ * some requests. fairness is handled differently
+ */
+ q->nr_requests = 1024;
+ cfqd->max_queued = q->nr_requests / 16;
+ q->nr_batching = cfq_queued;
+ cfqd->key_type = CFQ_KEY_TGID;
+ cfqd->find_best_crq = 1;
+ atomic_set(&cfqd->ref, 1);
+
+ cfqd->cfq_queued = cfq_queued;
+ cfqd->cfq_quantum = cfq_quantum;
+ cfqd->cfq_fifo_expire_r = cfq_fifo_expire_r;
+ cfqd->cfq_fifo_expire_w = cfq_fifo_expire_w;
+ cfqd->cfq_fifo_batch_expire = cfq_fifo_rate;
+ cfqd->cfq_back_max = cfq_back_max;
+ cfqd->cfq_back_penalty = cfq_back_penalty;
+
+ return 0;
+out_crqpool:
+ kfree(cfqd->cfq_hash);
+out_cfqhash:
+ kfree(cfqd->crq_hash);
+out_crqhash:
+ kfree(cfqd);
+ return -ENOMEM;
+}
+
+static void cfq_slab_kill(void)
+{
+ if (crq_pool)
+ kmem_cache_destroy(crq_pool);
+ if (cfq_pool)
+ kmem_cache_destroy(cfq_pool);
+ if (cfq_ioc_pool)
+ kmem_cache_destroy(cfq_ioc_pool);
+}
+
+static int __init cfq_slab_setup(void)
+{
+ crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0,
+ NULL, NULL);
+ if (!crq_pool)
+ goto fail;
+
+ cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0,
+ NULL, NULL);
+ if (!cfq_pool)
+ goto fail;
+
+ cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool",
+ sizeof(struct cfq_io_context), 0, 0, NULL, NULL);
+ if (!cfq_ioc_pool)
+ goto fail;
+
+ return 0;
+fail:
+ cfq_slab_kill();
+ return -ENOMEM;
+}
+
+
+/*
+ * sysfs parts below -->
+ */
+struct cfq_fs_entry {
+ struct attribute attr;
+ ssize_t (*show)(struct cfq_data *, char *);
+ ssize_t (*store)(struct cfq_data *, const char *, size_t);
+};
+
+static ssize_t
+cfq_var_show(unsigned int var, char *page)
+{
+ return sprintf(page, "%d\n", var);
+}
+
+static ssize_t
+cfq_var_store(unsigned int *var, const char *page, size_t count)
+{
+ char *p = (char *) page;
+
+ *var = simple_strtoul(p, &p, 10);
+ return count;
+}
+
+static ssize_t
+cfq_clear_elapsed(struct cfq_data *cfqd, const char *page, size_t count)
+{
+ max_elapsed_dispatch = max_elapsed_crq = 0;
+ return count;
+}
+
+static ssize_t
+cfq_set_key_type(struct cfq_data *cfqd, const char *page, size_t count)
+{
+ spin_lock_irq(cfqd->queue->queue_lock);
+ if (!strncmp(page, "pgid", 4))
+ cfqd->key_type = CFQ_KEY_PGID;
+ else if (!strncmp(page, "tgid", 4))
+ cfqd->key_type = CFQ_KEY_TGID;
+ else if (!strncmp(page, "uid", 3))
+ cfqd->key_type = CFQ_KEY_UID;
+ else if (!strncmp(page, "gid", 3))
+ cfqd->key_type = CFQ_KEY_GID;
+ spin_unlock_irq(cfqd->queue->queue_lock);
+ return count;
+}
+
+static ssize_t
+cfq_read_key_type(struct cfq_data *cfqd, char *page)
+{
+ ssize_t len = 0;
+ int i;
+
+ for (i = CFQ_KEY_PGID; i < CFQ_KEY_LAST; i++) {
+ if (cfqd->key_type == i)
+ len += sprintf(page+len, "[%s] ", cfq_key_types[i]);
+ else
+ len += sprintf(page+len, "%s ", cfq_key_types[i]);
+ }
+ len += sprintf(page+len, "\n");
+ return len;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
+static ssize_t __FUNC(struct cfq_data *cfqd, char *page) \
+{ \
+ unsigned int __data = __VAR; \
+ if (__CONV) \
+ __data = jiffies_to_msecs(__data); \
+ return cfq_var_show(__data, (page)); \
+}
+SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
+SHOW_FUNCTION(cfq_queued_show, cfqd->cfq_queued, 0);
+SHOW_FUNCTION(cfq_fifo_expire_r_show, cfqd->cfq_fifo_expire_r, 1);
+SHOW_FUNCTION(cfq_fifo_expire_w_show, cfqd->cfq_fifo_expire_w, 1);
+SHOW_FUNCTION(cfq_fifo_batch_expire_show, cfqd->cfq_fifo_batch_expire, 1);
+SHOW_FUNCTION(cfq_find_best_show, cfqd->find_best_crq, 0);
+SHOW_FUNCTION(cfq_back_max_show, cfqd->cfq_back_max, 0);
+SHOW_FUNCTION(cfq_back_penalty_show, cfqd->cfq_back_penalty, 0);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
+static ssize_t __FUNC(struct cfq_data *cfqd, const char *page, size_t count) \
+{ \
+ unsigned int __data; \
+ int ret = cfq_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(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
+STORE_FUNCTION(cfq_queued_store, &cfqd->cfq_queued, 1, UINT_MAX, 0);
+STORE_FUNCTION(cfq_fifo_expire_r_store, &cfqd->cfq_fifo_expire_r, 1, UINT_MAX, 1);
+STORE_FUNCTION(cfq_fifo_expire_w_store, &cfqd->cfq_fifo_expire_w, 1, UINT_MAX, 1);
+STORE_FUNCTION(cfq_fifo_batch_expire_store, &cfqd->cfq_fifo_batch_expire, 0, UINT_MAX, 1);
+STORE_FUNCTION(cfq_find_best_store, &cfqd->find_best_crq, 0, 1, 0);
+STORE_FUNCTION(cfq_back_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
+STORE_FUNCTION(cfq_back_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0);
+#undef STORE_FUNCTION
+
+static struct cfq_fs_entry cfq_quantum_entry = {
+ .attr = {.name = "quantum", .mode = S_IRUGO | S_IWUSR },
+ .show = cfq_quantum_show,
+ .store = cfq_quantum_store,
+};
+static struct cfq_fs_entry cfq_queued_entry = {
+ .attr = {.name = "queued", .mode = S_IRUGO | S_IWUSR },
+ .show = cfq_queued_show,
+ .store = cfq_queued_store,
+};
+static struct cfq_fs_entry cfq_fifo_expire_r_entry = {
+ .attr = {.name = "fifo_expire_sync", .mode = S_IRUGO | S_IWUSR },
+ .show = cfq_fifo_expire_r_show,
+ .store = cfq_fifo_expire_r_store,
+};
+static struct cfq_fs_entry cfq_fifo_expire_w_entry = {
+ .attr = {.name = "fifo_expire_async", .mode = S_IRUGO | S_IWUSR },
+ .show = cfq_fifo_expire_w_show,
+ .store = cfq_fifo_expire_w_store,
+};
+static struct cfq_fs_entry cfq_fifo_batch_expire_entry = {
+ .attr = {.name = "fifo_batch_expire", .mode = S_IRUGO | S_IWUSR },
+ .show = cfq_fifo_batch_expire_show,
+ .store = cfq_fifo_batch_expire_store,
+};
+static struct cfq_fs_entry cfq_find_best_entry = {
+ .attr = {.name = "find_best_crq", .mode = S_IRUGO | S_IWUSR },
+ .show = cfq_find_best_show,
+ .store = cfq_find_best_store,
+};
+static struct cfq_fs_entry cfq_back_max_entry = {
+ .attr = {.name = "back_seek_max", .mode = S_IRUGO | S_IWUSR },
+ .show = cfq_back_max_show,
+ .store = cfq_back_max_store,
+};
+static struct cfq_fs_entry cfq_back_penalty_entry = {
+ .attr = {.name = "back_seek_penalty", .mode = S_IRUGO | S_IWUSR },
+ .show = cfq_back_penalty_show,
+ .store = cfq_back_penalty_store,
+};
+static struct cfq_fs_entry cfq_clear_elapsed_entry = {
+ .attr = {.name = "clear_elapsed", .mode = S_IWUSR },
+ .store = cfq_clear_elapsed,
+};
+static struct cfq_fs_entry cfq_key_type_entry = {
+ .attr = {.name = "key_type", .mode = S_IRUGO | S_IWUSR },
+ .show = cfq_read_key_type,
+ .store = cfq_set_key_type,
+};
+
+static struct attribute *default_attrs[] = {
+ &cfq_quantum_entry.attr,
+ &cfq_queued_entry.attr,
+ &cfq_fifo_expire_r_entry.attr,
+ &cfq_fifo_expire_w_entry.attr,
+ &cfq_fifo_batch_expire_entry.attr,
+ &cfq_key_type_entry.attr,
+ &cfq_find_best_entry.attr,
+ &cfq_back_max_entry.attr,
+ &cfq_back_penalty_entry.attr,
+ &cfq_clear_elapsed_entry.attr,
+ NULL,
+};
+
+#define to_cfq(atr) container_of((atr), struct cfq_fs_entry, attr)
+
+static ssize_t
+cfq_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
+{
+ elevator_t *e = container_of(kobj, elevator_t, kobj);
+ struct cfq_fs_entry *entry = to_cfq(attr);
+
+ if (!entry->show)
+ return 0;
+
+ return entry->show(e->elevator_data, page);
+}
+
+static ssize_t
+cfq_attr_store(struct kobject *kobj, struct attribute *attr,
+ const char *page, size_t length)
+{
+ elevator_t *e = container_of(kobj, elevator_t, kobj);
+ struct cfq_fs_entry *entry = to_cfq(attr);
+
+ if (!entry->store)
+ return -EINVAL;
+
+ return entry->store(e->elevator_data, page, length);
+}
+
+static struct sysfs_ops cfq_sysfs_ops = {
+ .show = cfq_attr_show,
+ .store = cfq_attr_store,
+};
+
+static struct kobj_type cfq_ktype = {
+ .sysfs_ops = &cfq_sysfs_ops,
+ .default_attrs = default_attrs,
+};
+
+static struct elevator_type iosched_cfq = {
+ .ops = {
+ .elevator_merge_fn = cfq_merge,
+ .elevator_merged_fn = cfq_merged_request,
+ .elevator_merge_req_fn = cfq_merged_requests,
+ .elevator_next_req_fn = cfq_next_request,
+ .elevator_add_req_fn = cfq_insert_request,
+ .elevator_remove_req_fn = cfq_remove_request,
+ .elevator_requeue_req_fn = cfq_requeue_request,
+ .elevator_deactivate_req_fn = cfq_deactivate_request,
+ .elevator_queue_empty_fn = cfq_queue_empty,
+ .elevator_completed_req_fn = cfq_completed_request,
+ .elevator_former_req_fn = cfq_former_request,
+ .elevator_latter_req_fn = cfq_latter_request,
+ .elevator_set_req_fn = cfq_set_request,
+ .elevator_put_req_fn = cfq_put_request,
+ .elevator_may_queue_fn = cfq_may_queue,
+ .elevator_init_fn = cfq_init_queue,
+ .elevator_exit_fn = cfq_exit_queue,
+ },
+ .elevator_ktype = &cfq_ktype,
+ .elevator_name = "cfq",
+ .elevator_owner = THIS_MODULE,
+};
+
+static int __init cfq_init(void)
+{
+ int ret;
+
+ if (cfq_slab_setup())
+ return -ENOMEM;
+
+ ret = elv_register(&iosched_cfq);
+ if (!ret) {
+ __module_get(THIS_MODULE);
+ return 0;
+ }
+
+ cfq_slab_kill();
+ return ret;
+}
+
+static void __exit cfq_exit(void)
+{
+ cfq_slab_kill();
+ elv_unregister(&iosched_cfq);
+}
+
+module_init(cfq_init);
+module_exit(cfq_exit);
+
+MODULE_AUTHOR("Jens Axboe");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");