[PATCH] iosched: use hlist for request hashtable

Use hlist instead of list_head for request hashtable in deadline-iosched
and as-iosched. It also can remove the flag to know hashed or unhashed.

Signed-off-by: Akinobu Mita <mita@miraclelinux.com>
Signed-off-by: Jens Axboe <axboe@suse.de>

 block/as-iosched.c       |   45 +++++++++++++++++++--------------------------
 block/deadline-iosched.c |   39 ++++++++++++++++-----------------------
 2 files changed, 35 insertions(+), 49 deletions(-)

1 files changed, 19 insertions, 26 deletions

diff --git a/block/as-iosched.c b/block/as-iosched.c
index 0c750393be4a..9b13d72ffefa 100644
--- a/block/as-iosched.c
+++ b/block/as-iosched.c
@@ -96,7 +96,7 @@ struct as_data {
 
         struct as_rq *next_arq[2];      /* next in sort order */
         sector_t last_sector[2];        /* last REQ_SYNC & REQ_ASYNC sectors */
-        struct list_head *hash;         /* request hash */
+        struct hlist_head *hash;        /* request hash */
 
         unsigned long exit_prob;        /* probability a task will exit while
                                            being waited on */
@@ -165,8 +165,7 @@ struct as_rq {
         /*
          * request hash, key is the ending offset (for back merge lookup)
          */
-        struct list_head hash;
-        unsigned int on_hash;
+        struct hlist_node hash;
 
         /*
          * expire fifo
@@ -282,17 +281,15 @@ static const int as_hash_shift = 6;
 #define AS_HASH_FN(sec)         (hash_long(AS_HASH_BLOCK((sec)), as_hash_shift))
 #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)
 
 static inline void __as_del_arq_hash(struct as_rq *arq)
 {
-        arq->on_hash = 0;
-        list_del_init(&arq->hash);
+        hlist_del_init(&arq->hash);
 }
 
 static inline void as_del_arq_hash(struct as_rq *arq)
 {
-        if (arq->on_hash)
+        if (!hlist_unhashed(&arq->hash))
                 __as_del_arq_hash(arq);
 }
 
@@ -300,10 +297,9 @@ static void as_add_arq_hash(struct as_data *ad, struct as_rq *arq)
 {
         struct request *rq = arq->request;
 
-        BUG_ON(arq->on_hash);
+        BUG_ON(!hlist_unhashed(&arq->hash));
 
-        arq->on_hash = 1;
-        list_add(&arq->hash, &ad->hash[AS_HASH_FN(rq_hash_key(rq))]);
+        hlist_add_head(&arq->hash, &ad->hash[AS_HASH_FN(rq_hash_key(rq))]);
 }
 
 /*
@@ -312,31 +308,29 @@ static void as_add_arq_hash(struct as_data *ad, struct as_rq *arq)
 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))];
+        struct hlist_head *head = &ad->hash[AS_HASH_FN(rq_hash_key(rq))];
 
-        if (!arq->on_hash) {
+        if (hlist_unhashed(&arq->hash)) {
                 WARN_ON(1);
                 return;
         }
 
-        if (arq->hash.prev != head) {
-                list_del(&arq->hash);
-                list_add(&arq->hash, head);
+        if (&arq->hash != head->first) {
+                hlist_del(&arq->hash);
+                hlist_add_head(&arq->hash, head);
         }
 }
 
 static struct request *as_find_arq_hash(struct as_data *ad, sector_t offset)
 {
-        struct list_head *hash_list = &ad->hash[AS_HASH_FN(offset)];
-        struct list_head *entry, *next = hash_list->next;
+        struct hlist_head *hash_list = &ad->hash[AS_HASH_FN(offset)];
+        struct hlist_node *entry, *next;
+        struct as_rq *arq;
 
-        while ((entry = next) != hash_list) {
-                struct as_rq *arq = list_entry_hash(entry);
+        hlist_for_each_entry_safe(arq, entry, next, hash_list, hash) {
                 struct request *__rq = arq->request;
 
-                next = entry->next;
-
-                BUG_ON(!arq->on_hash);
+                BUG_ON(hlist_unhashed(&arq->hash));
 
                 if (!rq_mergeable(__rq)) {
                         as_del_arq_hash(arq);
@@ -1601,8 +1595,7 @@ static int as_set_request(request_queue_t *q, struct request *rq,
                 arq->request = rq;
                 arq->state = AS_RQ_PRESCHED;
                 arq->io_context = NULL;
-                INIT_LIST_HEAD(&arq->hash);
-                arq->on_hash = 0;
+                INIT_HLIST_NODE(&arq->hash);
                 INIT_LIST_HEAD(&arq->fifo);
                 rq->elevator_private = arq;
                 return 0;
@@ -1662,7 +1655,7 @@ static void *as_init_queue(request_queue_t *q, elevator_t *e)
 
         ad->q = q; /* Identify what queue the data belongs to */
 
-        ad->hash = kmalloc_node(sizeof(struct list_head)*AS_HASH_ENTRIES,
+        ad->hash = kmalloc_node(sizeof(struct hlist_head)*AS_HASH_ENTRIES,
                                 GFP_KERNEL, q->node);
         if (!ad->hash) {
                 kfree(ad);
@@ -1684,7 +1677,7 @@ static void *as_init_queue(request_queue_t *q, elevator_t *e)
         INIT_WORK(&ad->antic_work, as_work_handler, q);
 
         for (i = 0; i < AS_HASH_ENTRIES; i++)
-                INIT_LIST_HEAD(&ad->hash[i]);
+                INIT_HLIST_HEAD(&ad->hash[i]);
 
         INIT_LIST_HEAD(&ad->fifo_list[REQ_SYNC]);
         INIT_LIST_HEAD(&ad->fifo_list[REQ_ASYNC]);