From: Nick Piggin <piggin@cyberone.com.au>
The crazy HASH_VALID stuff now makes no difference now. It was there to
try to enforce no merging over a barrier, but it turned out that requests
can just be reordered. Jens picked this up a a while ago and fixed
deadline (and I AS) by simply dispatching all reqs on the queue on
encountering a barrier. The hash valid stuff didn't get cleaned up.
drivers/block/as-iosched.c | 31 ++++++++++---------------------
1 files changed, 10 insertions(+), 21 deletions(-)
diff -puN drivers/block/as-iosched.c~as-remove-hash-valid-stuff drivers/block/as-iosched.c
--- 25/drivers/block/as-iosched.c~as-remove-hash-valid-stuff 2003-08-02 11:42:14.000000000 -0700
+++ 25-akpm/drivers/block/as-iosched.c 2003-08-02 11:42:14.000000000 -0700
@@ -99,7 +99,6 @@ struct as_data {
sector_t last_sector[2]; /* last REQ_SYNC & REQ_ASYNC sectors */
struct list_head *dispatch; /* driver dispatch queue */
struct list_head *hash; /* request hash */
- unsigned long hash_valid_count; /* barrier hash count */
unsigned long current_batch_expires;
unsigned long last_check_fifo[2];
int changed_batch;
@@ -153,7 +152,7 @@ struct as_rq {
* request hash, key is the ending offset (for back merge lookup)
*/
struct list_head hash;
- unsigned long hash_valid_count;
+ unsigned int on_hash;
/*
* expire fifo
@@ -161,7 +160,7 @@ struct as_rq {
struct list_head fifo;
unsigned long expires;
- int is_sync;
+ unsigned int is_sync;
enum arq_state state; /* debug only */
};
@@ -238,23 +237,16 @@ static const int as_hash_shift = 6;
#define AS_HASH_ENTRIES (1 << as_hash_shift)
#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors)
#define list_entry_hash(ptr) list_entry((ptr), struct as_rq, hash)
-#define ON_HASH(arq) (arq)->hash_valid_count
-
-#define AS_INVALIDATE_HASH(ad) \
- do { \
- if (!++(ad)->hash_valid_count) \
- (ad)->hash_valid_count = 1; \
- } while (0)
static inline void __as_del_arq_hash(struct as_rq *arq)
{
- arq->hash_valid_count = 0;
+ arq->on_hash = 0;
list_del_init(&arq->hash);
}
static inline void as_del_arq_hash(struct as_rq *arq)
{
- if (ON_HASH(arq))
+ if (arq->on_hash)
__as_del_arq_hash(arq);
}
@@ -270,9 +262,9 @@ static void as_add_arq_hash(struct as_da
{
struct request *rq = arq->request;
- BUG_ON(ON_HASH(arq));
+ BUG_ON(arq->on_hash);
- arq->hash_valid_count = ad->hash_valid_count;
+ arq->on_hash = 1;
list_add(&arq->hash, &ad->hash[AS_HASH_FN(rq_hash_key(rq))]);
}
@@ -284,7 +276,7 @@ static inline void as_hot_arq_hash(struc
struct request *rq = arq->request;
struct list_head *head = &ad->hash[AS_HASH_FN(rq_hash_key(rq))];
- if (!ON_HASH(arq)) {
+ if (!arq->on_hash) {
WARN_ON(1);
return;
}
@@ -306,10 +298,9 @@ static struct request *as_find_arq_hash(
next = entry->next;
- BUG_ON(!ON_HASH(arq));
+ BUG_ON(!arq->on_hash);
- if (!rq_mergeable(__rq)
- || arq->hash_valid_count != ad->hash_valid_count) {
+ if (!rq_mergeable(__rq)) {
__as_del_arq_hash(arq);
continue;
}
@@ -1323,7 +1314,6 @@ as_insert_request(request_queue_t *q, st
struct as_rq *arq = RQ_DATA(rq);
if (unlikely(rq->flags & REQ_HARDBARRIER)) {
- AS_INVALIDATE_HASH(ad);
q->last_merge = NULL;
while (ad->next_arq[REQ_SYNC])
@@ -1573,7 +1563,7 @@ static int as_set_request(request_queue_
arq->state = AS_RQ_NEW;
arq->io_context = NULL;
INIT_LIST_HEAD(&arq->hash);
- arq->hash_valid_count = 0;
+ arq->on_hash = 0;
INIT_LIST_HEAD(&arq->fifo);
rq->elevator_private = arq;
return 0;
@@ -1662,7 +1652,6 @@ static int as_init(request_queue_t *q, e
ad->dispatch = &q->queue_head;
ad->fifo_expire[REQ_SYNC] = default_read_expire;
ad->fifo_expire[REQ_ASYNC] = default_write_expire;
- ad->hash_valid_count = 1;
ad->antic_expire = default_antic_expire;
ad->batch_expire[REQ_SYNC] = default_read_batch_expire;
ad->batch_expire[REQ_ASYNC] = default_write_batch_expire;
_