#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/delay.h>
#include <linux/blktrace_api.h>
+#include <linux/hash.h>
#include <asm/uaccess.h>
static DEFINE_SPINLOCK(elv_list_lock);
static LIST_HEAD(elv_list);
+/*
+ * Merge hash stuff.
+ */
+static const int elv_hash_shift = 6;
+#define ELV_HASH_BLOCK(sec) ((sec) >> 3)
+#define ELV_HASH_FN(sec) (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift))
+#define ELV_HASH_ENTRIES (1 << elv_hash_shift)
+#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors)
+#define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash))
+
/*
* can we safely merge with this request?
*/
static elevator_t *elevator_alloc(struct elevator_type *e)
{
- elevator_t *eq = kmalloc(sizeof(elevator_t), GFP_KERNEL);
- if (eq) {
- memset(eq, 0, sizeof(*eq));
- eq->ops = &e->ops;
- eq->elevator_type = e;
- kobject_init(&eq->kobj);
- snprintf(eq->kobj.name, KOBJ_NAME_LEN, "%s", "iosched");
- eq->kobj.ktype = &elv_ktype;
- mutex_init(&eq->sysfs_lock);
- } else {
- elevator_put(e);
- }
+ elevator_t *eq;
+ int i;
+
+ eq = kmalloc(sizeof(elevator_t), GFP_KERNEL);
+ if (unlikely(!eq))
+ goto err;
+
+ memset(eq, 0, sizeof(*eq));
+ eq->ops = &e->ops;
+ eq->elevator_type = e;
+ kobject_init(&eq->kobj);
+ snprintf(eq->kobj.name, KOBJ_NAME_LEN, "%s", "iosched");
+ eq->kobj.ktype = &elv_ktype;
+ mutex_init(&eq->sysfs_lock);
+
+ eq->hash = kmalloc(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, GFP_KERNEL);
+ if (!eq->hash)
+ goto err;
+
+ for (i = 0; i < ELV_HASH_ENTRIES; i++)
+ INIT_HLIST_HEAD(&eq->hash[i]);
+
return eq;
+err:
+ kfree(eq);
+ elevator_put(e);
+ return NULL;
}
static void elevator_release(struct kobject *kobj)
{
elevator_t *e = container_of(kobj, elevator_t, kobj);
+
elevator_put(e->elevator_type);
+ kfree(e->hash);
kfree(e);
}
kobject_put(&e->kobj);
}
+static inline void __elv_rqhash_del(struct request *rq)
+{
+ hlist_del_init(&rq->hash);
+}
+
+static void elv_rqhash_del(request_queue_t *q, struct request *rq)
+{
+ if (ELV_ON_HASH(rq))
+ __elv_rqhash_del(rq);
+}
+
+static void elv_rqhash_add(request_queue_t *q, struct request *rq)
+{
+ elevator_t *e = q->elevator;
+
+ BUG_ON(ELV_ON_HASH(rq));
+ hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]);
+}
+
+static void elv_rqhash_reposition(request_queue_t *q, struct request *rq)
+{
+ __elv_rqhash_del(rq);
+ elv_rqhash_add(q, rq);
+}
+
+static struct request *elv_rqhash_find(request_queue_t *q, sector_t offset)
+{
+ elevator_t *e = q->elevator;
+ struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)];
+ struct hlist_node *entry, *next;
+ struct request *rq;
+
+ hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) {
+ BUG_ON(!ELV_ON_HASH(rq));
+
+ if (unlikely(!rq_mergeable(rq))) {
+ __elv_rqhash_del(rq);
+ continue;
+ }
+
+ if (rq_hash_key(rq) == offset)
+ return rq;
+ }
+
+ return NULL;
+}
+
/*
* Insert rq into dispatch queue of q. Queue lock must be held on
* entry. If sort != 0, rq is sort-inserted; otherwise, rq will be
if (q->last_merge == rq)
q->last_merge = NULL;
+
+ elv_rqhash_del(q, rq);
+
q->nr_sorted--;
boundary = q->end_sector;
list_for_each_prev(entry, &q->queue_head) {
struct request *pos = list_entry_rq(entry);
- if (pos->flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED))
+ if (pos->cmd_flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED))
break;
if (rq->sector >= boundary) {
if (pos->sector < boundary)
list_add(&rq->queuelist, entry);
}
+/*
+ * This should be in elevator.h, but that requires pulling in rq and q
+ */
+void elv_dispatch_add_tail(struct request_queue *q, struct request *rq)
+{
+ if (q->last_merge == rq)
+ q->last_merge = NULL;
+
+ elv_rqhash_del(q, rq);
+
+ q->nr_sorted--;
+
+ q->end_sector = rq_end_sector(rq);
+ q->boundary_rq = rq;
+ list_add_tail(&rq->queuelist, &q->queue_head);
+}
+
int elv_merge(request_queue_t *q, struct request **req, struct bio *bio)
{
elevator_t *e = q->elevator;
+ struct request *__rq;
int ret;
+ /*
+ * First try one-hit cache.
+ */
if (q->last_merge) {
ret = elv_try_merge(q->last_merge, bio);
if (ret != ELEVATOR_NO_MERGE) {
}
}
+ /*
+ * See if our hash lookup can find a potential backmerge.
+ */
+ __rq = elv_rqhash_find(q, bio->bi_sector);
+ if (__rq && elv_rq_merge_ok(__rq, bio)) {
+ *req = __rq;
+ return ELEVATOR_BACK_MERGE;
+ }
+
if (e->ops->elevator_merge_fn)
return e->ops->elevator_merge_fn(q, req, bio);
if (e->ops->elevator_merged_fn)
e->ops->elevator_merged_fn(q, rq);
+ elv_rqhash_reposition(q, rq);
+
q->last_merge = rq;
}
if (e->ops->elevator_merge_req_fn)
e->ops->elevator_merge_req_fn(q, rq, next);
- q->nr_sorted--;
+ elv_rqhash_reposition(q, rq);
+ elv_rqhash_del(q, next);
+
+ q->nr_sorted--;
q->last_merge = rq;
}
e->ops->elevator_deactivate_req_fn(q, rq);
}
- rq->flags &= ~REQ_STARTED;
+ rq->cmd_flags &= ~REQ_STARTED;
elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE);
}
switch (where) {
case ELEVATOR_INSERT_FRONT:
- rq->flags |= REQ_SOFTBARRIER;
+ rq->cmd_flags |= REQ_SOFTBARRIER;
list_add(&rq->queuelist, &q->queue_head);
break;
case ELEVATOR_INSERT_BACK:
- rq->flags |= REQ_SOFTBARRIER;
+ rq->cmd_flags |= REQ_SOFTBARRIER;
elv_drain_elevator(q);
list_add_tail(&rq->queuelist, &q->queue_head);
/*
case ELEVATOR_INSERT_SORT:
BUG_ON(!blk_fs_request(rq));
- rq->flags |= REQ_SORTED;
+ rq->cmd_flags |= REQ_SORTED;
q->nr_sorted++;
- if (q->last_merge == NULL && rq_mergeable(rq))
- q->last_merge = rq;
+ if (rq_mergeable(rq)) {
+ elv_rqhash_add(q, rq);
+ if (!q->last_merge)
+ q->last_merge = rq;
+ }
+
/*
* Some ioscheds (cfq) run q->request_fn directly, so
* rq cannot be accessed after calling
* insertion; otherwise, requests should be requeued
* in ordseq order.
*/
- rq->flags |= REQ_SOFTBARRIER;
+ rq->cmd_flags |= REQ_SOFTBARRIER;
if (q->ordseq == 0) {
list_add(&rq->queuelist, &q->queue_head);
int plug)
{
if (q->ordcolor)
- rq->flags |= REQ_ORDERED_COLOR;
+ rq->cmd_flags |= REQ_ORDERED_COLOR;
- if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {
+ if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {
/*
* toggle ordered color
*/
q->end_sector = rq_end_sector(rq);
q->boundary_rq = rq;
}
- } else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT)
+ } else if (!(rq->cmd_flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT)
where = ELEVATOR_INSERT_BACK;
if (plug)
int ret;
while ((rq = __elv_next_request(q)) != NULL) {
- if (!(rq->flags & REQ_STARTED)) {
+ if (!(rq->cmd_flags & REQ_STARTED)) {
elevator_t *e = q->elevator;
/*
* it, a request that has been delayed should
* not be passed by new incoming requests
*/
- rq->flags |= REQ_STARTED;
+ rq->cmd_flags |= REQ_STARTED;
blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
}
q->boundary_rq = NULL;
}
- if ((rq->flags & REQ_DONTPREP) || !q->prep_rq_fn)
+ if ((rq->cmd_flags & REQ_DONTPREP) || !q->prep_rq_fn)
break;
ret = q->prep_rq_fn(q, rq);
nr_bytes = rq->data_len;
blkdev_dequeue_request(rq);
- rq->flags |= REQ_QUIET;
+ rq->cmd_flags |= REQ_QUIET;
end_that_request_chunk(rq, 0, nr_bytes);
end_that_request_last(rq, 0);
} else {
void elv_dequeue_request(request_queue_t *q, struct request *rq)
{
BUG_ON(list_empty(&rq->queuelist));
+ BUG_ON(ELV_ON_HASH(rq));
list_del_init(&rq->queuelist);
read_lock(&tasklist_lock);
do_each_thread(g, p) {
task_lock(p);
- e->ops.trim(p->io_context);
+ if (p->io_context)
+ e->ops.trim(p->io_context);
task_unlock(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);