#include <linux/slab.h>
#include <linux/init.h>
#include <linux/compiler.h>
+#include <linux/delay.h>
#include <asm/uaccess.h>
}
EXPORT_SYMBOL(elv_try_merge);
-inline int elv_try_last_merge(request_queue_t *q, struct bio *bio)
-{
- if (q->last_merge)
- return elv_try_merge(q->last_merge, bio);
-
- return ELEVATOR_NO_MERGE;
-}
-EXPORT_SYMBOL(elv_try_last_merge);
-
static struct elevator_type *elevator_find(const char *name)
{
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;
break;
}
}
- spin_unlock_irq(&elv_list_lock);
return e;
}
static struct elevator_type *elevator_get(const char *name)
{
- struct elevator_type *e = elevator_find(name);
+ struct elevator_type *e;
- if (!e)
- return NULL;
- if (!try_module_get(e->elevator_owner))
- return NULL;
+ spin_lock_irq(&elv_list_lock);
+
+ e = elevator_find(name);
+ if (e && !try_module_get(e->elevator_owner))
+ e = NULL;
+
+ spin_unlock_irq(&elv_list_lock);
return e;
}
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)
static void elevator_setup_default(void)
{
+ struct elevator_type *e;
+
/*
* check if default is set and exists
*/
- if (chosen_elevator[0] && elevator_find(chosen_elevator))
+ if (chosen_elevator[0] && (e = elevator_get(chosen_elevator))) {
+ elevator_put(e);
return;
+ }
#if defined(CONFIG_IOSCHED_AS)
strcpy(chosen_elevator, "anticipatory");
struct elevator_queue *eq;
int ret = 0;
+ INIT_LIST_HEAD(&q->queue_head);
+ q->last_merge = NULL;
+ q->end_sector = 0;
+ q->boundary_rq = NULL;
+
elevator_setup_default();
if (!name)
kfree(e);
}
+/*
+ * 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
+ * appended to the dispatch queue. To be used by specific elevators.
+ */
+void elv_dispatch_sort(request_queue_t *q, struct request *rq)
+{
+ sector_t boundary;
+ struct list_head *entry;
+
+ if (q->last_merge == rq)
+ q->last_merge = NULL;
+
+ 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))
+ break;
+ if (rq->sector >= boundary) {
+ if (pos->sector < boundary)
+ continue;
+ } else {
+ if (pos->sector >= boundary)
+ break;
+ }
+ if (rq->sector >= pos->sector)
+ break;
+ }
+
+ list_add(&rq->queuelist, entry);
+}
+
int elv_merge(request_queue_t *q, struct request **req, struct bio *bio)
{
elevator_t *e = q->elevator;
+ int ret;
+
+ if (q->last_merge) {
+ ret = elv_try_merge(q->last_merge, bio);
+ if (ret != ELEVATOR_NO_MERGE) {
+ *req = q->last_merge;
+ return ret;
+ }
+ }
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);
+
+ q->last_merge = rq;
}
void elv_merge_requests(request_queue_t *q, struct request *rq,
{
elevator_t *e = q->elevator;
- if (q->last_merge == next)
- q->last_merge = NULL;
-
if (e->ops->elevator_merge_req_fn)
e->ops->elevator_merge_req_fn(q, rq, next);
+
+ q->last_merge = rq;
}
-/*
- * For careful internal use by the block layer. Essentially the same as
- * a requeue in that it tells the io scheduler that this request is not
- * active in the driver or hardware anymore, but we don't want the request
- * added back to the scheduler. Function is not exported.
- */
-void elv_deactivate_request(request_queue_t *q, struct request *rq)
+void elv_requeue_request(request_queue_t *q, struct request *rq)
{
elevator_t *e = q->elevator;
* it already went through dequeue, we need to decrement the
* in_flight count again
*/
- if (blk_account_rq(rq))
+ if (blk_account_rq(rq)) {
q->in_flight--;
+ if (blk_sorted_rq(rq) && e->ops->elevator_deactivate_req_fn)
+ e->ops->elevator_deactivate_req_fn(q, rq);
+ }
rq->flags &= ~REQ_STARTED;
- if (e->ops->elevator_deactivate_req_fn)
- e->ops->elevator_deactivate_req_fn(q, rq);
-}
-
-void elv_requeue_request(request_queue_t *q, struct request *rq)
-{
- elv_deactivate_request(q, rq);
-
/*
* if this is the flush, requeue the original instead and drop the flush
*/
rq = rq->end_io_data;
}
- /*
- * the request is prepped and may have some resources allocated.
- * allowing unprepped requests to pass this one may cause resource
- * deadlock. turn on softbarrier.
- */
- rq->flags |= REQ_SOFTBARRIER;
-
- /*
- * if iosched has an explicit requeue hook, then use that. otherwise
- * just put the request at the front of the queue
- */
- 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);
+ __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);
}
void __elv_add_request(request_queue_t *q, struct request *rq, int where,
int plug)
{
- /*
- * barriers implicitly indicate back insertion
- */
- if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER) &&
- where == ELEVATOR_INSERT_SORT)
+ if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {
+ /*
+ * barriers implicitly indicate back insertion
+ */
+ if (where == ELEVATOR_INSERT_SORT)
+ where = ELEVATOR_INSERT_BACK;
+
+ /*
+ * this request is scheduling boundary, update end_sector
+ */
+ if (blk_fs_request(rq)) {
+ q->end_sector = rq_end_sector(rq);
+ q->boundary_rq = rq;
+ }
+ } else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT)
where = ELEVATOR_INSERT_BACK;
if (plug)
rq->q = q;
- if (!test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)) {
- q->elevator->ops->elevator_add_req_fn(q, rq, where);
+ switch (where) {
+ case ELEVATOR_INSERT_FRONT:
+ rq->flags |= REQ_SOFTBARRIER;
- if (blk_queue_plugged(q)) {
- int nrq = q->rq.count[READ] + q->rq.count[WRITE]
- - q->in_flight;
+ list_add(&rq->queuelist, &q->queue_head);
+ break;
- if (nrq >= q->unplug_thresh)
- __generic_unplug_device(q);
- }
- } else
+ case ELEVATOR_INSERT_BACK:
+ rq->flags |= REQ_SOFTBARRIER;
+
+ while (q->elevator->ops->elevator_dispatch_fn(q, 1))
+ ;
+ list_add_tail(&rq->queuelist, &q->queue_head);
/*
- * if drain is set, store the request "locally". when the drain
- * is finished, the requests will be handed ordered to the io
- * scheduler
+ * We kick the queue here for the following reasons.
+ * - The elevator might have returned NULL previously
+ * to delay requests and returned them now. As the
+ * queue wasn't empty before this request, ll_rw_blk
+ * won't run the queue on return, resulting in hang.
+ * - Usually, back inserted requests won't be merged
+ * with anything. There's no point in delaying queue
+ * processing.
*/
- list_add_tail(&rq->queuelist, &q->drain_list);
+ blk_remove_plug(q);
+ q->request_fn(q);
+ break;
+
+ case ELEVATOR_INSERT_SORT:
+ BUG_ON(!blk_fs_request(rq));
+ rq->flags |= REQ_SORTED;
+ q->elevator->ops->elevator_add_req_fn(q, rq);
+ if (q->last_merge == NULL && rq_mergeable(rq))
+ q->last_merge = rq;
+ break;
+
+ default:
+ printk(KERN_ERR "%s: bad insertion point %d\n",
+ __FUNCTION__, where);
+ BUG();
+ }
+
+ 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);
+ }
}
void elv_add_request(request_queue_t *q, struct request *rq, int where,
static inline struct request *__elv_next_request(request_queue_t *q)
{
- struct request *rq = q->elevator->ops->elevator_next_req_fn(q);
+ struct request *rq;
+
+ if (unlikely(list_empty(&q->queue_head) &&
+ !q->elevator->ops->elevator_dispatch_fn(q, 0)))
+ return NULL;
+
+ rq = list_entry_rq(q->queue_head.next);
/*
* if this is a barrier write and the device has to issue a
* flush sequence to support it, check how far we are
*/
- if (rq && blk_fs_request(rq) && blk_barrier_rq(rq)) {
+ if (blk_fs_request(rq) && blk_barrier_rq(rq)) {
BUG_ON(q->ordered == QUEUE_ORDERED_NONE);
if (q->ordered == QUEUE_ORDERED_FLUSH &&
int ret;
while ((rq = __elv_next_request(q)) != NULL) {
- /*
- * just mark as started even if we don't start it, a request
- * that has been delayed should not be passed by new incoming
- * requests
- */
- rq->flags |= REQ_STARTED;
+ if (!(rq->flags & REQ_STARTED)) {
+ elevator_t *e = q->elevator;
- if (rq == q->last_merge)
- q->last_merge = NULL;
+ /*
+ * This is the first time the device driver
+ * sees this request (possibly after
+ * requeueing). Notify IO scheduler.
+ */
+ if (blk_sorted_rq(rq) &&
+ e->ops->elevator_activate_req_fn)
+ e->ops->elevator_activate_req_fn(q, rq);
+
+ /*
+ * just mark as started even if we don't start
+ * it, a request that has been delayed should
+ * not be passed by new incoming requests
+ */
+ rq->flags |= REQ_STARTED;
+ }
+
+ if (!q->boundary_rq || q->boundary_rq == rq) {
+ q->end_sector = rq_end_sector(rq);
+ q->boundary_rq = NULL;
+ }
if ((rq->flags & REQ_DONTPREP) || !q->prep_rq_fn)
break;
/*
* the request may have been (partially) prepped.
* we need to keep this request in the front to
- * avoid resource deadlock. turn on softbarrier.
+ * avoid resource deadlock. REQ_STARTED will
+ * prevent other fs requests from passing this one.
*/
- rq->flags |= REQ_SOFTBARRIER;
rq = NULL;
break;
} else if (ret == BLKPREP_KILL) {
return rq;
}
-void elv_remove_request(request_queue_t *q, struct request *rq)
+void elv_dequeue_request(request_queue_t *q, struct request *rq)
{
- elevator_t *e = q->elevator;
+ BUG_ON(list_empty(&rq->queuelist));
+
+ list_del_init(&rq->queuelist);
/*
* the time frame between a request being removed from the lists
* and to it is freed is accounted as io that is in progress at
- * the driver side. note that we only account requests that the
- * driver has seen (REQ_STARTED set), to avoid false accounting
- * for request-request merges
+ * the driver side.
*/
if (blk_account_rq(rq))
q->in_flight++;
-
- /*
- * the main clearing point for q->last_merge is on retrieval of
- * request by driver (it calls elv_next_request()), but it _can_
- * also happen here if a request is added to the queue but later
- * deleted without ever being given to driver (merged with another
- * request).
- */
- if (rq == q->last_merge)
- q->last_merge = NULL;
-
- 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;
+ if (!list_empty(&q->queue_head))
+ return 0;
+
if (e->ops->elevator_queue_empty_fn)
return e->ops->elevator_queue_empty_fn(q);
- return list_empty(&q->queue_head);
+ return 1;
}
struct request *elv_latter_request(request_queue_t *q, struct request *rq)
}
int elv_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
- int gfp_mask)
+ gfp_t gfp_mask)
{
elevator_t *e = q->elevator;
/*
* request is released from the driver, io must be done
*/
- if (blk_account_rq(rq))
+ if (blk_account_rq(rq)) {
q->in_flight--;
-
- if (e->ops->elevator_completed_req_fn)
- e->ops->elevator_completed_req_fn(q, rq);
+ if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn)
+ e->ops->elevator_completed_req_fn(q, rq);
+ }
}
int elv_register_queue(struct request_queue *q)
int elv_register(struct elevator_type *e)
{
+ spin_lock_irq(&elv_list_lock);
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);
* 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.
+ * one, if the new one fails init for some reason.
*/
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;
+ elevator_t *old_elevator, *e;
+ /*
+ * Allocate new elevator
+ */
+ e = kmalloc(sizeof(elevator_t), GFP_KERNEL);
if (!e)
goto error;
/*
- * first step, drain requests from the block freelist
+ * Turn on BYPASS and drain all requests w/ elevator private data
*/
- blk_wait_queue_drained(q, 0);
+ spin_lock_irq(q->queue_lock);
+
+ set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
+
+ while (q->elevator->ops->elevator_dispatch_fn(q, 1))
+ ;
+
+ while (q->rq.elvpriv) {
+ spin_unlock_irq(q->queue_lock);
+ msleep(10);
+ spin_lock_irq(q->queue_lock);
+ }
+
+ spin_unlock_irq(q->queue_lock);
/*
* 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
*/
goto fail_register;
/*
- * finally exit old elevator and start queue again
+ * finally exit old elevator and turn off BYPASS.
*/
elevator_exit(old_elevator);
- blk_finish_queue_drain(q);
- elevator_put(noop_elevator);
+ clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
return;
fail_register:
* one again (along with re-adding the sysfs dir)
*/
elevator_exit(e);
+ e = NULL;
fail:
q->elevator = old_elevator;
elv_register_queue(q);
- blk_finish_queue_drain(q);
+ clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
+ kfree(e);
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);
}
return len;
}
+EXPORT_SYMBOL(elv_dispatch_sort);
EXPORT_SYMBOL(elv_add_request);
EXPORT_SYMBOL(__elv_add_request);
EXPORT_SYMBOL(elv_requeue_request);
EXPORT_SYMBOL(elv_next_request);
-EXPORT_SYMBOL(elv_remove_request);
+EXPORT_SYMBOL(elv_dequeue_request);
EXPORT_SYMBOL(elv_queue_empty);
EXPORT_SYMBOL(elv_completed_request);
EXPORT_SYMBOL(elevator_exit);
projects / linux-2.6-omap-h63xx.git / blobdiff