[PATCH] as-iosched: migrate to using the elevator rb functions

This removes the rbtree handling from AS.

Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Nick Piggin <npiggin@suse.de>

diff --git a/block/as-iosched.c b/block/as-iosched.c
index 9d0f15a..134545b 100644 (file)
--- a/block/as-iosched.c
+++ b/block/as-iosched.c
@@ -149,12 +149,6 @@ enum arq_state {
 };
 
 struct as_rq {
-       /*
-        * rbtree index, key is the starting offset
-        */
-       struct rb_node rb_node;
-       sector_t rb_key;
-
        struct request *request;
 
        struct io_context *io_context;  /* The submitting task */
@@ -268,101 +262,22 @@ static void as_put_io_context(struct as_rq *arq)
 /*
  * rb tree support functions
  */
-#define rb_entry_arq(node)     rb_entry((node), struct as_rq, rb_node)
 #define ARQ_RB_ROOT(ad, arq)   (&(ad)->sort_list[(arq)->is_sync])
-#define rq_rb_key(rq)          (rq)->sector
-
-/*
- * as_find_first_arq finds the first (lowest sector numbered) request
- * for the specified data_dir. Used to sweep back to the start of the disk
- * (1-way elevator) after we process the last (highest sector) request.
- */
-static struct as_rq *as_find_first_arq(struct as_data *ad, int data_dir)
-{
-       struct rb_node *n = ad->sort_list[data_dir].rb_node;
-
-       if (n == NULL)
-               return NULL;
-
-       for (;;) {
-               if (n->rb_left == NULL)
-                       return rb_entry_arq(n);
-
-               n = n->rb_left;
-       }
-}
-
-/*
- * Add the request to the rb tree if it is unique.  If there is an alias (an
- * existing request against the same sector), which can happen when using
- * direct IO, then return the alias.
- */
-static struct as_rq *__as_add_arq_rb(struct as_data *ad, struct as_rq *arq)
-{
-       struct rb_node **p = &ARQ_RB_ROOT(ad, arq)->rb_node;
-       struct rb_node *parent = NULL;
-       struct as_rq *__arq;
-       struct request *rq = arq->request;
-
-       arq->rb_key = rq_rb_key(rq);
-
-       while (*p) {
-               parent = *p;
-               __arq = rb_entry_arq(parent);
-
-               if (arq->rb_key < __arq->rb_key)
-                       p = &(*p)->rb_left;
-               else if (arq->rb_key > __arq->rb_key)
-                       p = &(*p)->rb_right;
-               else
-                       return __arq;
-       }
-
-       rb_link_node(&arq->rb_node, parent, p);
-       rb_insert_color(&arq->rb_node, ARQ_RB_ROOT(ad, arq));
 
-       return NULL;
-}
-
-static void as_add_arq_rb(struct as_data *ad, struct as_rq *arq)
+static void as_add_arq_rb(struct as_data *ad, struct request *rq)
 {
-       struct as_rq *alias;
+       struct as_rq *arq = RQ_DATA(rq);
+       struct request *alias;
 
-       while ((unlikely(alias = __as_add_arq_rb(ad, arq)))) {
-               as_move_to_dispatch(ad, alias);
+       while ((unlikely(alias = elv_rb_add(ARQ_RB_ROOT(ad, arq), rq)))) {
+               as_move_to_dispatch(ad, RQ_DATA(alias));
                as_antic_stop(ad);
        }
 }
 
-static inline void as_del_arq_rb(struct as_data *ad, struct as_rq *arq)
-{
-       if (RB_EMPTY_NODE(&arq->rb_node)) {
-               WARN_ON(1);
-               return;
-       }
-
-       rb_erase(&arq->rb_node, ARQ_RB_ROOT(ad, arq));
-       RB_CLEAR_NODE(&arq->rb_node);
-}
-
-static struct request *
-as_find_arq_rb(struct as_data *ad, sector_t sector, int data_dir)
+static inline void as_del_arq_rb(struct as_data *ad, struct request *rq)
 {
-       struct rb_node *n = ad->sort_list[data_dir].rb_node;
-       struct as_rq *arq;
-
-       while (n) {
-               arq = rb_entry_arq(n);
-
-               if (sector < arq->rb_key)
-                       n = n->rb_left;
-               else if (sector > arq->rb_key)
-                       n = n->rb_right;
-               else
-                       return arq->request;
-       }
-
-       return NULL;
+       elv_rb_del(ARQ_RB_ROOT(ad, RQ_DATA(rq)), rq);
 }
 
 /*
@@ -455,32 +370,29 @@ as_choose_req(struct as_data *ad, struct as_rq *arq1, struct as_rq *arq2)
  * this with as_choose_req form the basis for how the scheduler chooses
  * what request to process next. Anticipation works on top of this.
  */
-static struct as_rq *as_find_next_arq(struct as_data *ad, struct as_rq *last)
+static struct as_rq *as_find_next_arq(struct as_data *ad, struct as_rq *arq)
 {
-       const int data_dir = last->is_sync;
-       struct as_rq *ret;
+       struct request *last = arq->request;
        struct rb_node *rbnext = rb_next(&last->rb_node);
        struct rb_node *rbprev = rb_prev(&last->rb_node);
-       struct as_rq *arq_next, *arq_prev;
+       struct as_rq *next = NULL, *prev = NULL;
 
-       BUG_ON(!RB_EMPTY_NODE(&last->rb_node));
+       BUG_ON(RB_EMPTY_NODE(&last->rb_node));
 
        if (rbprev)
-               arq_prev = rb_entry_arq(rbprev);
-       else
-               arq_prev = NULL;
+               prev = RQ_DATA(rb_entry_rq(rbprev));
 
        if (rbnext)
-               arq_next = rb_entry_arq(rbnext);
+               next = RQ_DATA(rb_entry_rq(rbnext));
        else {
-               arq_next = as_find_first_arq(ad, data_dir);
-               if (arq_next == last)
-                       arq_next = NULL;
-       }
+               const int data_dir = arq->is_sync;
 
-       ret = as_choose_req(ad, arq_next, arq_prev);
+               rbnext = rb_first(&ad->sort_list[data_dir]);
+               if (rbnext && rbnext != &last->rb_node)
+                       next = RQ_DATA(rb_entry_rq(rbnext));
+       }
 
-       return ret;
+       return as_choose_req(ad, next, prev);
 }
 
 /*
@@ -982,7 +894,7 @@ static void as_remove_queued_request(request_queue_t *q, struct request *rq)
                ad->next_arq[data_dir] = as_find_next_arq(ad, arq);
 
        list_del_init(&arq->fifo);
-       as_del_arq_rb(ad, arq);
+       as_del_arq_rb(ad, rq);
 }
 
 /*
@@ -1039,7 +951,7 @@ static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq)
        struct request *rq = arq->request;
        const int data_dir = arq->is_sync;
 
-       BUG_ON(RB_EMPTY_NODE(&arq->rb_node));
+       BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
 
        as_antic_stop(ad);
        ad->antic_status = ANTIC_OFF;
@@ -1269,7 +1181,7 @@ static void as_add_request(request_queue_t *q, struct request *rq)
                atomic_inc(&arq->io_context->aic->nr_queued);
        }
 
-       as_add_arq_rb(ad, arq);
+       as_add_arq_rb(ad, rq);
 
        /*
         * set expire time (only used for reads) and add to fifo list
@@ -1315,32 +1227,6 @@ static int as_queue_empty(request_queue_t *q)
                && list_empty(&ad->fifo_list[REQ_SYNC]);
 }
 
-static struct request *as_former_request(request_queue_t *q,
-                                       struct request *rq)
-{
-       struct as_rq *arq = RQ_DATA(rq);
-       struct rb_node *rbprev = rb_prev(&arq->rb_node);
-       struct request *ret = NULL;
-
-       if (rbprev)
-               ret = rb_entry_arq(rbprev)->request;
-
-       return ret;
-}
-
-static struct request *as_latter_request(request_queue_t *q,
-                                       struct request *rq)
-{
-       struct as_rq *arq = RQ_DATA(rq);
-       struct rb_node *rbnext = rb_next(&arq->rb_node);
-       struct request *ret = NULL;
-
-       if (rbnext)
-               ret = rb_entry_arq(rbnext)->request;
-
-       return ret;
-}
-
 static int
 as_merge(request_queue_t *q, struct request **req, struct bio *bio)
 {
@@ -1351,7 +1237,7 @@ as_merge(request_queue_t *q, struct request **req, struct bio *bio)
        /*
         * check for front merge
         */
-       __rq = as_find_arq_rb(ad, rb_key, bio_data_dir(bio));
+       __rq = elv_rb_find(&ad->sort_list[bio_data_dir(bio)], rb_key);
        if (__rq && elv_rq_merge_ok(__rq, bio)) {
                *req = __rq;
                return ELEVATOR_FRONT_MERGE;
@@ -1360,17 +1246,16 @@ as_merge(request_queue_t *q, struct request **req, struct bio *bio)
        return ELEVATOR_NO_MERGE;
 }
 
-static void as_merged_request(request_queue_t *q, struct request *req)
+static void as_merged_request(request_queue_t *q, struct request *req, int type)
 {
        struct as_data *ad = q->elevator->elevator_data;
-       struct as_rq *arq = RQ_DATA(req);
 
        /*
         * if the merge was a front merge, we need to reposition request
         */
-       if (rq_rb_key(req) != arq->rb_key) {
-               as_del_arq_rb(ad, arq);
-               as_add_arq_rb(ad, arq);
+       if (type == ELEVATOR_FRONT_MERGE) {
+               as_del_arq_rb(ad, req);
+               as_add_arq_rb(ad, req);
                /*
                 * Note! At this stage of this and the next function, our next
                 * request may not be optimal - eg the request may have "grown"
@@ -1382,18 +1267,12 @@ static void as_merged_request(request_queue_t *q, struct request *req)
 static void as_merged_requests(request_queue_t *q, struct request *req,
                                struct request *next)
 {
-       struct as_data *ad = q->elevator->elevator_data;
        struct as_rq *arq = RQ_DATA(req);
        struct as_rq *anext = RQ_DATA(next);
 
        BUG_ON(!arq);
        BUG_ON(!anext);
 
-       if (rq_rb_key(req) != arq->rb_key) {
-               as_del_arq_rb(ad, arq);
-               as_add_arq_rb(ad, arq);
-       }
-
        /*
         * if anext expires before arq, assign its expire time to arq
         * and move into anext position (anext will be deleted) in fifo
@@ -1468,7 +1347,6 @@ static int as_set_request(request_queue_t *q, struct request *rq,
 
        if (arq) {
                memset(arq, 0, sizeof(*arq));
-               RB_CLEAR_NODE(&arq->rb_node);
                arq->request = rq;
                arq->state = AS_RQ_PRESCHED;
                arq->io_context = NULL;
@@ -1654,8 +1532,8 @@ static struct elevator_type iosched_as = {
                .elevator_deactivate_req_fn =   as_deactivate_request,
                .elevator_queue_empty_fn =      as_queue_empty,
                .elevator_completed_req_fn =    as_completed_request,
-               .elevator_former_req_fn =       as_former_request,
-               .elevator_latter_req_fn =       as_latter_request,
+               .elevator_former_req_fn =       elv_rb_former_request,
+               .elevator_latter_req_fn =       elv_rb_latter_request,
                .elevator_set_req_fn =          as_set_request,
                .elevator_put_req_fn =          as_put_request,
                .elevator_may_queue_fn =        as_may_queue,