#include <asm/uaccess.h>
+static DEFINE_SPINLOCK(elv_list_lock);
+static LIST_HEAD(elv_list);
+
/*
* can we safely merge with this request?
*/
return 0;
}
+EXPORT_SYMBOL(elv_rq_merge_ok);
inline int elv_try_merge(struct request *__rq, struct bio *bio)
{
return ret;
}
+EXPORT_SYMBOL(elv_try_merge);
inline int elv_try_last_merge(request_queue_t *q, struct bio *bio)
{
return ELEVATOR_NO_MERGE;
}
+EXPORT_SYMBOL(elv_try_last_merge);
-/*
- * general block -> elevator interface starts here
- */
-int elevator_init(request_queue_t *q, elevator_t *type)
+struct elevator_type *elevator_find(const char *name)
{
- elevator_t *e = &q->elevator;
+ struct elevator_type *e = NULL;
+ struct list_head *entry;
+
+ spin_lock_irq(&elv_list_lock);
+ list_for_each(entry, &elv_list) {
+ struct elevator_type *__e;
- memcpy(e, type, sizeof(*e));
+ __e = list_entry(entry, struct elevator_type, list);
+
+ if (!strcmp(__e->elevator_name, name)) {
+ e = __e;
+ break;
+ }
+ }
+ spin_unlock_irq(&elv_list_lock);
+
+ return e;
+}
+
+static void elevator_put(struct elevator_type *e)
+{
+ module_put(e->elevator_owner);
+}
+
+static struct elevator_type *elevator_get(const char *name)
+{
+ struct elevator_type *e = elevator_find(name);
+
+ if (!e)
+ return NULL;
+ if (!try_module_get(e->elevator_owner))
+ return NULL;
+
+ return e;
+}
+
+static int elevator_attach(request_queue_t *q, struct elevator_type *e,
+ struct elevator_queue *eq)
+{
+ int ret = 0;
+
+ memset(eq, 0, sizeof(*eq));
+ eq->ops = &e->ops;
+ eq->elevator_type = e;
INIT_LIST_HEAD(&q->queue_head);
q->last_merge = NULL;
+ q->elevator = eq;
+
+ if (eq->ops->elevator_init_fn)
+ ret = eq->ops->elevator_init_fn(q, eq);
+
+ return ret;
+}
- if (e->elevator_init_fn)
- return e->elevator_init_fn(q, e);
+static char chosen_elevator[16];
+static void elevator_setup_default(void)
+{
+ /*
+ * check if default is set and exists
+ */
+ if (chosen_elevator[0] && elevator_find(chosen_elevator))
+ return;
+
+#if defined(CONFIG_IOSCHED_AS)
+ strcpy(chosen_elevator, "anticipatory");
+#elif defined(CONFIG_IOSCHED_DEADLINE)
+ strcpy(chosen_elevator, "deadline");
+#elif defined(CONFIG_IOSCHED_CFQ)
+ strcpy(chosen_elevator, "cfq");
+#elif defined(CONFIG_IOSCHED_NOOP)
+ strcpy(chosen_elevator, "noop");
+#else
+#error "You must build at least 1 IO scheduler into the kernel"
+#endif
+}
+
+static int __init elevator_setup(char *str)
+{
+ strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1);
return 0;
}
-void elevator_exit(request_queue_t *q)
+__setup("elevator=", elevator_setup);
+
+int elevator_init(request_queue_t *q, char *name)
+{
+ struct elevator_type *e = NULL;
+ struct elevator_queue *eq;
+ int ret = 0;
+
+ elevator_setup_default();
+
+ if (!name)
+ name = chosen_elevator;
+
+ e = elevator_get(name);
+ if (!e)
+ return -EINVAL;
+
+ eq = kmalloc(sizeof(struct elevator_queue), GFP_KERNEL);
+ if (!eq) {
+ elevator_put(e->elevator_type);
+ return -ENOMEM;
+ }
+
+ ret = elevator_attach(q, e, eq);
+ if (ret) {
+ kfree(eq);
+ elevator_put(e->elevator_type);
+ }
+
+ return ret;
+}
+
+void elevator_exit(elevator_t *e)
{
- elevator_t *e = &q->elevator;
+ if (e->ops->elevator_exit_fn)
+ e->ops->elevator_exit_fn(e);
- if (e->elevator_exit_fn)
- e->elevator_exit_fn(q, e);
+ elevator_put(e->elevator_type);
+ e->elevator_type = NULL;
+ kfree(e);
}
int elevator_global_init(void)
int elv_merge(request_queue_t *q, struct request **req, struct bio *bio)
{
- elevator_t *e = &q->elevator;
+ elevator_t *e = q->elevator;
- if (e->elevator_merge_fn)
- return e->elevator_merge_fn(q, req, bio);
+ if (e->ops->elevator_merge_fn)
+ return e->ops->elevator_merge_fn(q, req, bio);
return ELEVATOR_NO_MERGE;
}
void elv_merged_request(request_queue_t *q, struct request *rq)
{
- elevator_t *e = &q->elevator;
+ elevator_t *e = q->elevator;
- if (e->elevator_merged_fn)
- e->elevator_merged_fn(q, rq);
+ if (e->ops->elevator_merged_fn)
+ e->ops->elevator_merged_fn(q, rq);
}
void elv_merge_requests(request_queue_t *q, struct request *rq,
struct request *next)
{
- elevator_t *e = &q->elevator;
+ elevator_t *e = q->elevator;
if (q->last_merge == next)
q->last_merge = NULL;
- if (e->elevator_merge_req_fn)
- e->elevator_merge_req_fn(q, rq, next);
+ if (e->ops->elevator_merge_req_fn)
+ e->ops->elevator_merge_req_fn(q, rq, next);
}
void elv_requeue_request(request_queue_t *q, struct request *rq)
* if iosched has an explicit requeue hook, then use that. otherwise
* just put the request at the front of the queue
*/
- if (q->elevator.elevator_requeue_req_fn)
- q->elevator.elevator_requeue_req_fn(q, rq);
+ if (q->elevator->ops->elevator_requeue_req_fn)
+ q->elevator->ops->elevator_requeue_req_fn(q, rq);
else
__elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);
}
blk_plug_device(q);
rq->q = q;
- q->elevator.elevator_add_req_fn(q, rq, where);
- if (blk_queue_plugged(q)) {
- int nrq = q->rq.count[READ] + q->rq.count[WRITE] - q->in_flight;
+ if (!test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)) {
+ q->elevator->ops->elevator_add_req_fn(q, rq, where);
- if (nrq == q->unplug_thresh)
- __generic_unplug_device(q);
- }
+ if (blk_queue_plugged(q)) {
+ int nrq = q->rq.count[READ] + q->rq.count[WRITE]
+ - q->in_flight;
+ if (nrq == q->unplug_thresh)
+ __generic_unplug_device(q);
+ }
+ } else
+ /*
+ * if drain is set, store the request "locally". when the drain
+ * is finished, the requests will be handed ordered to the io
+ * scheduler
+ */
+ list_add_tail(&rq->queuelist, &q->drain_list);
}
void elv_add_request(request_queue_t *q, struct request *rq, int where,
static inline struct request *__elv_next_request(request_queue_t *q)
{
- return q->elevator.elevator_next_req_fn(q);
+ return q->elevator->ops->elevator_next_req_fn(q);
}
struct request *elv_next_request(request_queue_t *q)
end_that_request_chunk(rq, 0, nr_bytes);
end_that_request_last(rq);
} else {
- printk("%s: bad return=%d\n", __FUNCTION__, ret);
+ printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__,
+ ret);
break;
}
}
void elv_remove_request(request_queue_t *q, struct request *rq)
{
- elevator_t *e = &q->elevator;
+ elevator_t *e = q->elevator;
/*
* the time frame between a request being removed from the lists
if (rq == q->last_merge)
q->last_merge = NULL;
- if (e->elevator_remove_req_fn)
- e->elevator_remove_req_fn(q, rq);
+ if (e->ops->elevator_remove_req_fn)
+ e->ops->elevator_remove_req_fn(q, rq);
}
int elv_queue_empty(request_queue_t *q)
{
- elevator_t *e = &q->elevator;
+ elevator_t *e = q->elevator;
- if (e->elevator_queue_empty_fn)
- return e->elevator_queue_empty_fn(q);
+ if (e->ops->elevator_queue_empty_fn)
+ return e->ops->elevator_queue_empty_fn(q);
return list_empty(&q->queue_head);
}
{
struct list_head *next;
- elevator_t *e = &q->elevator;
+ elevator_t *e = q->elevator;
- if (e->elevator_latter_req_fn)
- return e->elevator_latter_req_fn(q, rq);
+ if (e->ops->elevator_latter_req_fn)
+ return e->ops->elevator_latter_req_fn(q, rq);
next = rq->queuelist.next;
if (next != &q->queue_head && next != &rq->queuelist)
{
struct list_head *prev;
- elevator_t *e = &q->elevator;
+ elevator_t *e = q->elevator;
- if (e->elevator_former_req_fn)
- return e->elevator_former_req_fn(q, rq);
+ if (e->ops->elevator_former_req_fn)
+ return e->ops->elevator_former_req_fn(q, rq);
prev = rq->queuelist.prev;
if (prev != &q->queue_head && prev != &rq->queuelist)
int elv_set_request(request_queue_t *q, struct request *rq, int gfp_mask)
{
- elevator_t *e = &q->elevator;
+ elevator_t *e = q->elevator;
- if (e->elevator_set_req_fn)
- return e->elevator_set_req_fn(q, rq, gfp_mask);
+ if (e->ops->elevator_set_req_fn)
+ return e->ops->elevator_set_req_fn(q, rq, gfp_mask);
rq->elevator_private = NULL;
return 0;
void elv_put_request(request_queue_t *q, struct request *rq)
{
- elevator_t *e = &q->elevator;
+ elevator_t *e = q->elevator;
- if (e->elevator_put_req_fn)
- e->elevator_put_req_fn(q, rq);
+ if (e->ops->elevator_put_req_fn)
+ e->ops->elevator_put_req_fn(q, rq);
}
int elv_may_queue(request_queue_t *q, int rw)
{
- elevator_t *e = &q->elevator;
+ elevator_t *e = q->elevator;
- if (e->elevator_may_queue_fn)
- return e->elevator_may_queue_fn(q, rw);
+ if (e->ops->elevator_may_queue_fn)
+ return e->ops->elevator_may_queue_fn(q, rw);
- return 0;
+ return ELV_MQUEUE_MAY;
}
void elv_completed_request(request_queue_t *q, struct request *rq)
{
- elevator_t *e = &q->elevator;
+ elevator_t *e = q->elevator;
/*
* request is released from the driver, io must be done
if (blk_account_rq(rq))
q->in_flight--;
- if (e->elevator_completed_req_fn)
- e->elevator_completed_req_fn(q, rq);
+ if (e->ops->elevator_completed_req_fn)
+ e->ops->elevator_completed_req_fn(q, rq);
}
int elv_register_queue(struct request_queue *q)
{
- elevator_t *e;
-
- e = &q->elevator;
+ elevator_t *e = q->elevator;
e->kobj.parent = kobject_get(&q->kobj);
if (!e->kobj.parent)
return -EBUSY;
snprintf(e->kobj.name, KOBJ_NAME_LEN, "%s", "iosched");
- e->kobj.ktype = e->elevator_ktype;
+ e->kobj.ktype = e->elevator_type->elevator_ktype;
return kobject_register(&e->kobj);
}
void elv_unregister_queue(struct request_queue *q)
{
if (q) {
- elevator_t * e = &q->elevator;
+ elevator_t *e = q->elevator;
kobject_unregister(&e->kobj);
kobject_put(&q->kobj);
}
}
+int elv_register(struct elevator_type *e)
+{
+ if (elevator_find(e->elevator_name))
+ BUG();
+
+ spin_lock_irq(&elv_list_lock);
+ list_add_tail(&e->list, &elv_list);
+ spin_unlock_irq(&elv_list_lock);
+
+ printk(KERN_INFO "io scheduler %s registered", e->elevator_name);
+ if (!strcmp(e->elevator_name, chosen_elevator))
+ printk(" (default)");
+ printk("\n");
+ return 0;
+}
+EXPORT_SYMBOL_GPL(elv_register);
+
+void elv_unregister(struct elevator_type *e)
+{
+ spin_lock_irq(&elv_list_lock);
+ list_del_init(&e->list);
+ spin_unlock_irq(&elv_list_lock);
+}
+EXPORT_SYMBOL_GPL(elv_unregister);
+
+/*
+ * switch to new_e io scheduler. be careful not to introduce deadlocks -
+ * we don't free the old io scheduler, before we have allocated what we
+ * need for the new one. this way we have a chance of going back to the old
+ * one, if the new one fails init for some reason. we also do an intermediate
+ * switch to noop to ensure safety with stack-allocated requests, since they
+ * don't originate from the block layer allocator. noop is safe here, because
+ * it never needs to touch the elevator itself for completion events. DRAIN
+ * flags will make sure we don't touch it for additions either.
+ */
+static void elevator_switch(request_queue_t *q, struct elevator_type *new_e)
+{
+ elevator_t *e = kmalloc(sizeof(elevator_t), GFP_KERNEL);
+ struct elevator_type *noop_elevator = NULL;
+ elevator_t *old_elevator;
+
+ if (!e)
+ goto error;
+
+ /*
+ * first step, drain requests from the block freelist
+ */
+ blk_wait_queue_drained(q, 0);
+
+ /*
+ * unregister old elevator data
+ */
+ elv_unregister_queue(q);
+ old_elevator = q->elevator;
+
+ /*
+ * next step, switch to noop since it uses no private rq structures
+ * and doesn't allocate any memory for anything. then wait for any
+ * non-fs requests in-flight
+ */
+ noop_elevator = elevator_get("noop");
+ spin_lock_irq(q->queue_lock);
+ elevator_attach(q, noop_elevator, e);
+ spin_unlock_irq(q->queue_lock);
+
+ blk_wait_queue_drained(q, 1);
+
+ /*
+ * attach and start new elevator
+ */
+ if (elevator_attach(q, new_e, e))
+ goto fail;
+
+ if (elv_register_queue(q))
+ goto fail_register;
+
+ /*
+ * finally exit old elevator and start queue again
+ */
+ elevator_exit(old_elevator);
+ blk_finish_queue_drain(q);
+ elevator_put(noop_elevator);
+ return;
+
+fail_register:
+ /*
+ * switch failed, exit the new io scheduler and reattach the old
+ * one again (along with re-adding the sysfs dir)
+ */
+ elevator_exit(e);
+fail:
+ q->elevator = old_elevator;
+ elv_register_queue(q);
+ blk_finish_queue_drain(q);
+error:
+ if (noop_elevator)
+ elevator_put(noop_elevator);
+ elevator_put(new_e);
+ printk(KERN_ERR "elevator: switch to %s failed\n",new_e->elevator_name);
+}
+
+ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count)
+{
+ char elevator_name[ELV_NAME_MAX];
+ struct elevator_type *e;
+
+ memset(elevator_name, 0, sizeof(elevator_name));
+ strncpy(elevator_name, name, sizeof(elevator_name));
+
+ if (elevator_name[strlen(elevator_name) - 1] == '\n')
+ elevator_name[strlen(elevator_name) - 1] = '\0';
+
+ e = elevator_get(elevator_name);
+ if (!e) {
+ printk(KERN_ERR "elevator: type %s not found\n", elevator_name);
+ return -EINVAL;
+ }
+
+ if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name))
+ return count;
+
+ elevator_switch(q, e);
+ return count;
+}
+
+ssize_t elv_iosched_show(request_queue_t *q, char *name)
+{
+ elevator_t *e = q->elevator;
+ struct elevator_type *elv = e->elevator_type;
+ struct list_head *entry;
+ int len = 0;
+
+ spin_lock_irq(q->queue_lock);
+ list_for_each(entry, &elv_list) {
+ struct elevator_type *__e;
+
+ __e = list_entry(entry, struct elevator_type, list);
+ if (!strcmp(elv->elevator_name, __e->elevator_name))
+ len += sprintf(name+len, "[%s] ", elv->elevator_name);
+ else
+ len += sprintf(name+len, "%s ", __e->elevator_name);
+ }
+ spin_unlock_irq(q->queue_lock);
+
+ len += sprintf(len+name, "\n");
+ return len;
+}
+
module_init(elevator_global_init);
EXPORT_SYMBOL(elv_add_request);
git://git.onelab.eu / linux-2.6.git / blobdiff