From: Nick Piggin <piggin@cyberone.com.au>
I have tested this on my disks and cdroms, but they don't represent
what all drivers might do. I have asked Jarkko Lehti with his dvd writing
problem to try it...
drivers/block/as-iosched.c | 101 +++++++++++++++++++++++++++++++--------------
1 files changed, 70 insertions(+), 31 deletions(-)
diff -puN drivers/block/as-iosched.c~as-request-poisoning drivers/block/as-iosched.c
--- 25/drivers/block/as-iosched.c~as-request-poisoning 2003-11-09 16:39:52.000000000 -0800
+++ 25-akpm/drivers/block/as-iosched.c 2003-11-09 16:39:52.000000000 -0800
@@ -136,6 +136,10 @@ enum arq_state {
scheduler */
AS_RQ_DISPATCHED, /* On the dispatch list. It belongs to the
driver now */
+ AS_RQ_PRESCHED, /* Debug poisoning for requests being used */
+ AS_RQ_REMOVED,
+ AS_RQ_MERGED,
+ AS_RQ_POSTSCHED, /* when they shouldn't be */
};
struct as_rq {
@@ -893,12 +897,22 @@ static void as_completed_request(request
{
struct as_data *ad = q->elevator.elevator_data;
struct as_rq *arq = RQ_DATA(rq);
- struct as_io_context *aic;
WARN_ON(!list_empty(&rq->queuelist));
- if (unlikely(arq->state != AS_RQ_DISPATCHED))
- return;
+ if (arq->state == AS_RQ_PRESCHED) {
+ WARN_ON(arq->io_context);
+ goto out;
+ }
+
+ if (arq->state == AS_RQ_MERGED)
+ goto out_ioc;
+
+ if (arq->state != AS_RQ_REMOVED) {
+ printk("arq->state %d\n", arq->state);
+ WARN_ON(1);
+ goto out;
+ }
if (!blk_fs_request(rq))
return;
@@ -925,10 +939,7 @@ static void as_completed_request(request
ad->new_batch = 0;
}
- if (!arq->io_context)
- return;
-
- if (ad->io_context == arq->io_context) {
+ if (ad->io_context == arq->io_context && ad->io_context) {
ad->antic_start = jiffies;
ad->ioc_finished = 1;
if (ad->antic_status == ANTIC_WAIT_REQ) {
@@ -940,18 +951,23 @@ static void as_completed_request(request
}
}
- aic = arq->io_context->aic;
- if (!aic)
- return;
+out_ioc:
+ if (!arq->io_context)
+ goto out;
- spin_lock(&aic->lock);
if (arq->is_sync == REQ_SYNC) {
- set_bit(AS_TASK_IORUNNING, &aic->state);
- aic->last_end_request = jiffies;
+ struct as_io_context *aic = arq->io_context->aic;
+ if (aic) {
+ spin_lock(&aic->lock);
+ set_bit(AS_TASK_IORUNNING, &aic->state);
+ aic->last_end_request = jiffies;
+ spin_unlock(&aic->lock);
+ }
}
- spin_unlock(&aic->lock);
put_io_context(arq->io_context);
+out:
+ arq->state = AS_RQ_POSTSCHED;
}
/*
@@ -1020,14 +1036,14 @@ static void as_remove_request(request_qu
struct as_rq *arq = RQ_DATA(rq);
if (unlikely(arq->state == AS_RQ_NEW))
- return;
-
- if (!arq) {
- WARN_ON(1);
- return;
- }
+ goto out;
if (ON_RB(&arq->rb_node)) {
+ if (arq->state != AS_RQ_QUEUED) {
+ printk("arq->state %d\n", arq->state);
+ WARN_ON(1);
+ goto out;
+ }
/*
* We'll lose the aliased request(s) here. I don't think this
* will ever happen, but if it does, hopefully someone will
@@ -1035,8 +1051,16 @@ static void as_remove_request(request_qu
*/
WARN_ON(!list_empty(&rq->queuelist));
as_remove_queued_request(q, rq);
- } else
+ } else {
+ if (arq->state != AS_RQ_DISPATCHED) {
+ printk("arq->state %d\n", arq->state);
+ WARN_ON(1);
+ goto out;
+ }
as_remove_dispatched_request(q, rq);
+ }
+out:
+ arq->state = AS_RQ_REMOVED;
}
/*
@@ -1214,9 +1238,9 @@ static int as_dispatch_request(struct as
*/
goto dispatch_writes;
- if (ad->batch_data_dir == REQ_ASYNC) {
+ if (ad->batch_data_dir == REQ_ASYNC) {
WARN_ON(ad->new_batch);
- ad->changed_batch = 1;
+ ad->changed_batch = 1;
}
ad->batch_data_dir = REQ_SYNC;
arq = list_entry_fifo(ad->fifo_list[ad->batch_data_dir].next);
@@ -1232,8 +1256,8 @@ static int as_dispatch_request(struct as
dispatch_writes:
BUG_ON(RB_EMPTY(&ad->sort_list[REQ_ASYNC]));
- if (ad->batch_data_dir == REQ_SYNC) {
- ad->changed_batch = 1;
+ if (ad->batch_data_dir == REQ_SYNC) {
+ ad->changed_batch = 1;
/*
* new_batch might be 1 when the queue runs out of
@@ -1276,8 +1300,6 @@ fifo_expired:
ad->new_batch = 1;
ad->changed_batch = 0;
-
-// arq->request->flags |= REQ_SOFTBARRIER;
}
/*
@@ -1402,6 +1424,11 @@ static void as_requeue_request(request_q
struct as_rq *arq = RQ_DATA(rq);
if (arq) {
+ if (arq->state != AS_RQ_REMOVED) {
+ printk("arq->state %d\n", arq->state);
+ WARN_ON(1);
+ }
+
arq->state = AS_RQ_DISPATCHED;
if (arq->io_context && arq->io_context->aic)
atomic_inc(&arq->io_context->aic->nr_dispatched);
@@ -1421,12 +1448,18 @@ as_insert_request(request_queue_t *q, st
struct as_data *ad = q->elevator.elevator_data;
struct as_rq *arq = RQ_DATA(rq);
-#if 0
+ if (arq) {
+ if (arq->state != AS_RQ_PRESCHED) {
+ printk("arq->state: %d\n", arq->state);
+ WARN_ON(1);
+ }
+ arq->state = AS_RQ_NEW;
+ }
+
/* barriers must flush the reorder queue */
if (unlikely(rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)
&& where == ELEVATOR_INSERT_SORT))
where = ELEVATOR_INSERT_BACK;
-#endif
switch (where) {
case ELEVATOR_INSERT_BACK:
@@ -1661,7 +1694,8 @@ as_merged_requests(request_queue_t *q, s
* kill knowledge of next, this one is a goner
*/
as_remove_queued_request(q, next);
- put_io_context(anext->io_context);
+
+ anext->state = AS_RQ_MERGED;
}
/*
@@ -1694,6 +1728,11 @@ static void as_put_request(request_queue
return;
}
+ if (arq->state != AS_RQ_POSTSCHED) {
+ printk("arq->state %d\n", arq->state);
+ WARN_ON(1);
+ }
+
mempool_free(arq, ad->arq_pool);
rq->elevator_private = NULL;
}
@@ -1707,7 +1746,7 @@ static int as_set_request(request_queue_
memset(arq, 0, sizeof(*arq));
RB_CLEAR(&arq->rb_node);
arq->request = rq;
- arq->state = AS_RQ_NEW;
+ arq->state = AS_RQ_PRESCHED;
arq->io_context = NULL;
INIT_LIST_HEAD(&arq->hash);
arq->on_hash = 0;
_