[PATCH] AS: remove hash valid stuff

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.

diff --git a/drivers/block/as-iosched.c b/drivers/block/as-iosched.c
index 957e42d1af7b89c00e74c9f1993e9ff920cedfbd..65b49eced37f02c51940ec1442da5dec20b15f36 100644 (file)
--- a/drivers/block/as-iosched.c
+++ b/drivers/block/as-iosched.c
@@ -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_data *ad, struct as_rq *arq)
 {
        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(struct as_data *ad, struct as_rq *arq)
        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(struct as_data *ad, sector_t offset)
 
                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, struct request *rq,
        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_t *q, struct request *rq, int gfp_mask)
                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, elevator_t *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;