[PATCH] as-iosched: kill arq

Get rid of the as_rq request type. With the added elevator_private2, we
have enough room in struct request to get rid of any arq allocation/free
for each request.

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

1 files changed, 118 insertions, 195 deletions

diff --git a/block/as-iosched.c b/block/as-iosched.c
index dca0b0563ca0..02eb9333898f 100644
--- a/block/as-iosched.c
+++ b/block/as-iosched.c
@@ -92,7 +92,7 @@ struct as_data {
         struct rb_root sort_list[2];
         struct list_head fifo_list[2];
 
-        struct as_rq *next_arq[2];      /* next in sort order */
+        struct request *next_rq[2];     /* next in sort order */
         sector_t last_sector[2];        /* last REQ_SYNC & REQ_ASYNC sectors */
 
         unsigned long exit_prob;        /* probability a task will exit while
@@ -113,7 +113,6 @@ struct as_data {
         int write_batch_count;          /* max # of reqs in a write batch */
         int current_write_count;        /* how many requests left this batch */
         int write_batch_idled;          /* has the write batch gone idle? */
-        mempool_t *arq_pool;
 
         enum anticipation_status antic_status;
         unsigned long antic_start;      /* jiffies: when it started */
@@ -146,22 +145,14 @@ enum arq_state {
         AS_RQ_POSTSCHED,        /* when they shouldn't be */
 };
 
-struct as_rq {
-        struct request *request;
-
-        struct io_context *io_context;  /* The submitting task */
-
-        enum arq_state state;
-};
-
-#define RQ_DATA(rq)     ((struct as_rq *) (rq)->elevator_private)
-
-static kmem_cache_t *arq_pool;
+#define RQ_IOC(rq)      ((struct io_context *) (rq)->elevator_private)
+#define RQ_STATE(rq)    ((enum arq_state)(rq)->elevator_private2)
+#define RQ_SET_STATE(rq, state) ((rq)->elevator_private2 = (void *) state)
 
 static atomic_t ioc_count = ATOMIC_INIT(0);
 static struct completion *ioc_gone;
 
-static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq);
+static void as_move_to_dispatch(struct as_data *ad, struct request *rq);
 static void as_antic_stop(struct as_data *ad);
 
 /*
@@ -231,23 +222,23 @@ static struct io_context *as_get_io_context(void)
         return ioc;
 }
 
-static void as_put_io_context(struct as_rq *arq)
+static void as_put_io_context(struct request *rq)
 {
         struct as_io_context *aic;
 
-        if (unlikely(!arq->io_context))
+        if (unlikely(!RQ_IOC(rq)))
                 return;
 
-        aic = arq->io_context->aic;
+        aic = RQ_IOC(rq)->aic;
 
-        if (rq_is_sync(arq->request) && aic) {
+        if (rq_is_sync(rq) && aic) {
                 spin_lock(&aic->lock);
                 set_bit(AS_TASK_IORUNNING, &aic->state);
                 aic->last_end_request = jiffies;
                 spin_unlock(&aic->lock);
         }
 
-        put_io_context(arq->io_context);
+        put_io_context(RQ_IOC(rq));
 }
 
 /*
@@ -255,17 +246,17 @@ static void as_put_io_context(struct as_rq *arq)
  */
 #define RQ_RB_ROOT(ad, rq)      (&(ad)->sort_list[rq_is_sync((rq))])
 
-static void as_add_arq_rb(struct as_data *ad, struct request *rq)
+static void as_add_rq_rb(struct as_data *ad, struct request *rq)
 {
         struct request *alias;
 
         while ((unlikely(alias = elv_rb_add(RQ_RB_ROOT(ad, rq), rq)))) {
-                as_move_to_dispatch(ad, RQ_DATA(alias));
+                as_move_to_dispatch(ad, alias);
                 as_antic_stop(ad);
         }
 }
 
-static inline void as_del_arq_rb(struct as_data *ad, struct request *rq)
+static inline void as_del_rq_rb(struct as_data *ad, struct request *rq)
 {
         elv_rb_del(RQ_RB_ROOT(ad, rq), rq);
 }
@@ -285,26 +276,26 @@ static inline void as_del_arq_rb(struct as_data *ad, struct request *rq)
  * as_choose_req selects the preferred one of two requests of the same data_dir
  * ignoring time - eg. timeouts, which is the job of as_dispatch_request
  */
-static struct as_rq *
-as_choose_req(struct as_data *ad, struct as_rq *arq1, struct as_rq *arq2)
+static struct request *
+as_choose_req(struct as_data *ad, struct request *rq1, struct request *rq2)
 {
         int data_dir;
         sector_t last, s1, s2, d1, d2;
         int r1_wrap=0, r2_wrap=0;       /* requests are behind the disk head */
         const sector_t maxback = MAXBACK;
 
-        if (arq1 == NULL || arq1 == arq2)
-                return arq2;
-        if (arq2 == NULL)
-                return arq1;
+        if (rq1 == NULL || rq1 == rq2)
+                return rq2;
+        if (rq2 == NULL)
+                return rq1;
 
-        data_dir = rq_is_sync(arq1->request);
+        data_dir = rq_is_sync(rq1);
 
         last = ad->last_sector[data_dir];
-        s1 = arq1->request->sector;
-        s2 = arq2->request->sector;
+        s1 = rq1->sector;
+        s2 = rq2->sector;
 
-        BUG_ON(data_dir != rq_is_sync(arq2->request));
+        BUG_ON(data_dir != rq_is_sync(rq2));
 
         /*
          * Strict one way elevator _except_ in the case where we allow
@@ -331,55 +322,55 @@ as_choose_req(struct as_data *ad, struct as_rq *arq1, struct as_rq *arq2)
 
         /* Found required data */
         if (!r1_wrap && r2_wrap)
-                return arq1;
+                return rq1;
         else if (!r2_wrap && r1_wrap)
-                return arq2;
+                return rq2;
         else if (r1_wrap && r2_wrap) {
                 /* both behind the head */
                 if (s1 <= s2)
-                        return arq1;
+                        return rq1;
                 else
-                        return arq2;
+                        return rq2;
         }
 
         /* Both requests in front of the head */
         if (d1 < d2)
-                return arq1;
+                return rq1;
         else if (d2 < d1)
-                return arq2;
+                return rq2;
         else {
                 if (s1 >= s2)
-                        return arq1;
+                        return rq1;
                 else
-                        return arq2;
+                        return rq2;
         }
 }
 
 /*
- * as_find_next_arq finds the next request after @prev in elevator order.
+ * as_find_next_rq finds the next request after @prev in elevator order.
  * 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 *arq)
+static struct request *
+as_find_next_rq(struct as_data *ad, struct request *last)
 {
-        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 *next = NULL, *prev = NULL;
+        struct request *next = NULL, *prev = NULL;
 
         BUG_ON(RB_EMPTY_NODE(&last->rb_node));
 
         if (rbprev)
-                prev = RQ_DATA(rb_entry_rq(rbprev));
+                prev = rb_entry_rq(rbprev);
 
         if (rbnext)
-                next = RQ_DATA(rb_entry_rq(rbnext));
+                next = rb_entry_rq(rbnext);
         else {
                 const int data_dir = rq_is_sync(last);
 
                 rbnext = rb_first(&ad->sort_list[data_dir]);
                 if (rbnext && rbnext != &last->rb_node)
-                        next = RQ_DATA(rb_entry_rq(rbnext));
+                        next = rb_entry_rq(rbnext);
         }
 
         return as_choose_req(ad, next, prev);
@@ -575,11 +566,11 @@ static void as_update_iohist(struct as_data *ad, struct as_io_context *aic,
  * previous one issued.
  */
 static int as_close_req(struct as_data *ad, struct as_io_context *aic,
-                                struct as_rq *arq)
+                        struct request *rq)
 {
         unsigned long delay;    /* milliseconds */
         sector_t last = ad->last_sector[ad->batch_data_dir];
-        sector_t next = arq->request->sector;
+        sector_t next = rq->sector;
         sector_t delta; /* acceptable close offset (in sectors) */
         sector_t s;
 
@@ -636,7 +627,7 @@ static int as_close_req(struct as_data *ad, struct as_io_context *aic,
  *
  * If this task has queued some other IO, do not enter enticipation.
  */
-static int as_can_break_anticipation(struct as_data *ad, struct as_rq *arq)
+static int as_can_break_anticipation(struct as_data *ad, struct request *rq)
 {
         struct io_context *ioc;
         struct as_io_context *aic;
@@ -644,7 +635,7 @@ static int as_can_break_anticipation(struct as_data *ad, struct as_rq *arq)
         ioc = ad->io_context;
         BUG_ON(!ioc);
 
-        if (arq && ioc == arq->io_context) {
+        if (rq && ioc == RQ_IOC(rq)) {
                 /* request from same process */
                 return 1;
         }
@@ -671,7 +662,7 @@ static int as_can_break_anticipation(struct as_data *ad, struct as_rq *arq)
                 return 1;
         }
 
-        if (arq && rq_is_sync(arq->request) && as_close_req(ad, aic, arq)) {
+        if (rq && rq_is_sync(rq) && as_close_req(ad, aic, rq)) {
                 /*
                  * Found a close request that is not one of ours.
                  *
@@ -687,7 +678,7 @@ static int as_can_break_anticipation(struct as_data *ad, struct as_rq *arq)
                         ad->exit_no_coop = (7*ad->exit_no_coop)/8;
                 }
 
-                as_update_iohist(ad, aic, arq->request);
+                as_update_iohist(ad, aic, rq);
                 return 1;
         }
 
@@ -714,10 +705,10 @@ static int as_can_break_anticipation(struct as_data *ad, struct as_rq *arq)
 }
 
 /*
- * as_can_anticipate indicates whether we should either run arq
+ * as_can_anticipate indicates whether we should either run rq
  * or keep anticipating a better request.
  */
-static int as_can_anticipate(struct as_data *ad, struct as_rq *arq)
+static int as_can_anticipate(struct as_data *ad, struct request *rq)
 {
         if (!ad->io_context)
                 /*
@@ -731,7 +722,7 @@ static int as_can_anticipate(struct as_data *ad, struct as_rq *arq)
                  */
                 return 0;
 
-        if (as_can_break_anticipation(ad, arq))
+        if (as_can_break_anticipation(ad, rq))
                 /*
                  * This request is a good candidate. Don't keep anticipating,
                  * run it.
@@ -749,16 +740,16 @@ static int as_can_anticipate(struct as_data *ad, struct as_rq *arq)
 }
 
 /*
- * as_update_arq must be called whenever a request (arq) is added to
+ * as_update_rq must be called whenever a request (rq) is added to
  * the sort_list. This function keeps caches up to date, and checks if the
  * request might be one we are "anticipating"
  */
-static void as_update_arq(struct as_data *ad, struct as_rq *arq)
+static void as_update_rq(struct as_data *ad, struct request *rq)
 {
-        const int data_dir = rq_is_sync(arq->request);
+        const int data_dir = rq_is_sync(rq);
 
-        /* keep the next_arq cache up to date */
-        ad->next_arq[data_dir] = as_choose_req(ad, arq, ad->next_arq[data_dir]);
+        /* keep the next_rq cache up to date */
+        ad->next_rq[data_dir] = as_choose_req(ad, rq, ad->next_rq[data_dir]);
 
         /*
          * have we been anticipating this request?
@@ -767,7 +758,7 @@ static void as_update_arq(struct as_data *ad, struct as_rq *arq)
          */
         if (ad->antic_status == ANTIC_WAIT_REQ
                         || ad->antic_status == ANTIC_WAIT_NEXT) {
-                if (as_can_break_anticipation(ad, arq))
+                if (as_can_break_anticipation(ad, rq))
                         as_antic_stop(ad);
         }
 }
@@ -807,12 +798,11 @@ static void update_write_batch(struct as_data *ad)
 static void as_completed_request(request_queue_t *q, struct request *rq)
 {
         struct as_data *ad = q->elevator->elevator_data;
-        struct as_rq *arq = RQ_DATA(rq);
 
         WARN_ON(!list_empty(&rq->queuelist));
 
-        if (arq->state != AS_RQ_REMOVED) {
-                printk("arq->state %d\n", arq->state);
+        if (RQ_STATE(rq) != AS_RQ_REMOVED) {
+                printk("rq->state %d\n", RQ_STATE(rq));
                 WARN_ON(1);
                 goto out;
         }
@@ -839,7 +829,7 @@ static void as_completed_request(request_queue_t *q, struct request *rq)
                 ad->new_batch = 0;
         }
 
-        if (ad->io_context == arq->io_context && ad->io_context) {
+        if (ad->io_context == RQ_IOC(rq) && ad->io_context) {
                 ad->antic_start = jiffies;
                 ad->ioc_finished = 1;
                 if (ad->antic_status == ANTIC_WAIT_REQ) {
@@ -851,9 +841,9 @@ static void as_completed_request(request_queue_t *q, struct request *rq)
                 }
         }
 
-        as_put_io_context(arq);
+        as_put_io_context(rq);
 out:
-        arq->state = AS_RQ_POSTSCHED;
+        RQ_SET_STATE(rq, AS_RQ_POSTSCHED);
 }
 
 /*
@@ -864,26 +854,27 @@ out:
  */
 static void as_remove_queued_request(request_queue_t *q, struct request *rq)
 {
-        struct as_rq *arq = RQ_DATA(rq);
         const int data_dir = rq_is_sync(rq);
         struct as_data *ad = q->elevator->elevator_data;
+        struct io_context *ioc;
 
-        WARN_ON(arq->state != AS_RQ_QUEUED);
+        WARN_ON(RQ_STATE(rq) != AS_RQ_QUEUED);
 
-        if (arq->io_context && arq->io_context->aic) {
-                BUG_ON(!atomic_read(&arq->io_context->aic->nr_queued));
-                atomic_dec(&arq->io_context->aic->nr_queued);
+        ioc = RQ_IOC(rq);
+        if (ioc && ioc->aic) {
+                BUG_ON(!atomic_read(&ioc->aic->nr_queued));
+                atomic_dec(&ioc->aic->nr_queued);
         }
 
         /*
-         * Update the "next_arq" cache if we are about to remove its
+         * Update the "next_rq" cache if we are about to remove its
          * entry
          */
-        if (ad->next_arq[data_dir] == arq)
-                ad->next_arq[data_dir] = as_find_next_arq(ad, arq);
+        if (ad->next_rq[data_dir] == rq)
+                ad->next_rq[data_dir] = as_find_next_rq(ad, rq);
 
         rq_fifo_clear(rq);
-        as_del_arq_rb(ad, rq);
+        as_del_rq_rb(ad, rq);
 }
 
 /*
@@ -935,9 +926,8 @@ static inline int as_batch_expired(struct as_data *ad)
 /*
  * move an entry to dispatch queue
  */
-static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq)
+static void as_move_to_dispatch(struct as_data *ad, struct request *rq)
 {
-        struct request *rq = arq->request;
         const int data_dir = rq_is_sync(rq);
 
         BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
@@ -947,13 +937,14 @@ static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq)
 
         /*
          * This has to be set in order to be correctly updated by
-         * as_find_next_arq
+         * as_find_next_rq
          */
         ad->last_sector[data_dir] = rq->sector + rq->nr_sectors;
 
         if (data_dir == REQ_SYNC) {
+                struct io_context *ioc = RQ_IOC(rq);
                 /* In case we have to anticipate after this */
-                copy_io_context(&ad->io_context, &arq->io_context);
+                copy_io_context(&ad->io_context, &ioc);
         } else {
                 if (ad->io_context) {
                         put_io_context(ad->io_context);
@@ -965,19 +956,19 @@ static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq)
         }
         ad->ioc_finished = 0;
 
-        ad->next_arq[data_dir] = as_find_next_arq(ad, arq);
+        ad->next_rq[data_dir] = as_find_next_rq(ad, rq);
 
         /*
          * take it off the sort and fifo list, add to dispatch queue
          */
         as_remove_queued_request(ad->q, rq);
-        WARN_ON(arq->state != AS_RQ_QUEUED);
+        WARN_ON(RQ_STATE(rq) != AS_RQ_QUEUED);
 
         elv_dispatch_sort(ad->q, rq);
 
-        arq->state = AS_RQ_DISPATCHED;
-        if (arq->io_context && arq->io_context->aic)
-                atomic_inc(&arq->io_context->aic->nr_dispatched);
+        RQ_SET_STATE(rq, AS_RQ_DISPATCHED);
+        if (RQ_IOC(rq) && RQ_IOC(rq)->aic)
+                atomic_inc(&RQ_IOC(rq)->aic->nr_dispatched);
         ad->nr_dispatched++;
 }
 
@@ -989,9 +980,9 @@ static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq)
 static int as_dispatch_request(request_queue_t *q, int force)
 {
         struct as_data *ad = q->elevator->elevator_data;
-        struct as_rq *arq;
         const int reads = !list_empty(&ad->fifo_list[REQ_SYNC]);
         const int writes = !list_empty(&ad->fifo_list[REQ_ASYNC]);
+        struct request *rq;
 
         if (unlikely(force)) {
                 /*
@@ -1007,14 +998,14 @@ static int as_dispatch_request(request_queue_t *q, int force)
                 ad->changed_batch = 0;
                 ad->new_batch = 0;
 
-                while (ad->next_arq[REQ_SYNC]) {
-                        as_move_to_dispatch(ad, ad->next_arq[REQ_SYNC]);
+                while (ad->next_rq[REQ_SYNC]) {
+                        as_move_to_dispatch(ad, ad->next_rq[REQ_SYNC]);
                         dispatched++;
                 }
                 ad->last_check_fifo[REQ_SYNC] = jiffies;
 
-                while (ad->next_arq[REQ_ASYNC]) {
-                        as_move_to_dispatch(ad, ad->next_arq[REQ_ASYNC]);
+                while (ad->next_rq[REQ_ASYNC]) {
+                        as_move_to_dispatch(ad, ad->next_rq[REQ_ASYNC]);
                         dispatched++;
                 }
                 ad->last_check_fifo[REQ_ASYNC] = jiffies;
@@ -1038,19 +1029,19 @@ static int as_dispatch_request(request_queue_t *q, int force)
                 /*
                  * batch is still running or no reads or no writes
                  */
-                arq = ad->next_arq[ad->batch_data_dir];
+                rq = ad->next_rq[ad->batch_data_dir];
 
                 if (ad->batch_data_dir == REQ_SYNC && ad->antic_expire) {
                         if (as_fifo_expired(ad, REQ_SYNC))
                                 goto fifo_expired;
 
-                        if (as_can_anticipate(ad, arq)) {
+                        if (as_can_anticipate(ad, rq)) {
                                 as_antic_waitreq(ad);
                                 return 0;
                         }
                 }
 
-                if (arq) {
+                if (rq) {
                         /* we have a "next request" */
                         if (reads && !writes)
                                 ad->current_batch_expires =
@@ -1078,7 +1069,7 @@ static int as_dispatch_request(request_queue_t *q, int force)
                         ad->changed_batch = 1;
                 }
                 ad->batch_data_dir = REQ_SYNC;
-                arq = RQ_DATA(rq_entry_fifo(ad->fifo_list[REQ_SYNC].next));
+                rq = rq_entry_fifo(ad->fifo_list[REQ_SYNC].next);
                 ad->last_check_fifo[ad->batch_data_dir] = jiffies;
                 goto dispatch_request;
         }
@@ -1104,7 +1095,7 @@ dispatch_writes:
                 ad->batch_data_dir = REQ_ASYNC;
                 ad->current_write_count = ad->write_batch_count;
                 ad->write_batch_idled = 0;
-                arq = ad->next_arq[ad->batch_data_dir];
+                rq = ad->next_rq[ad->batch_data_dir];
                 goto dispatch_request;
         }
 
@@ -1118,7 +1109,7 @@ dispatch_request:
 
         if (as_fifo_expired(ad, ad->batch_data_dir)) {
 fifo_expired:
-                arq = RQ_DATA(rq_entry_fifo(ad->fifo_list[ad->batch_data_dir].next));
+                rq = rq_entry_fifo(ad->fifo_list[ad->batch_data_dir].next);
         }
 
         if (ad->changed_batch) {
@@ -1137,34 +1128,33 @@ fifo_expired:
         }
 
         /*
-         * arq is the selected appropriate request.
+         * rq is the selected appropriate request.
          */
-        as_move_to_dispatch(ad, arq);
+        as_move_to_dispatch(ad, rq);
 
         return 1;
 }
 
 /*
- * add arq to rbtree and fifo
+ * add rq to rbtree and fifo
  */
 static void as_add_request(request_queue_t *q, struct request *rq)
 {
         struct as_data *ad = q->elevator->elevator_data;
-        struct as_rq *arq = RQ_DATA(rq);
         int data_dir;
 
-        arq->state = AS_RQ_NEW;
+        RQ_SET_STATE(rq, AS_RQ_NEW);
 
         data_dir = rq_is_sync(rq);
 
-        arq->io_context = as_get_io_context();
+        rq->elevator_private = as_get_io_context();
 
-        if (arq->io_context) {
-                as_update_iohist(ad, arq->io_context->aic, arq->request);
-                atomic_inc(&arq->io_context->aic->nr_queued);
+        if (RQ_IOC(rq)) {
+                as_update_iohist(ad, RQ_IOC(rq)->aic, rq);
+                atomic_inc(&RQ_IOC(rq)->aic->nr_queued);
         }
 
-        as_add_arq_rb(ad, rq);
+        as_add_rq_rb(ad, rq);
 
         /*
          * set expire time (only used for reads) and add to fifo list
@@ -1172,28 +1162,24 @@ static void as_add_request(request_queue_t *q, struct request *rq)
         rq_set_fifo_time(rq, jiffies + ad->fifo_expire[data_dir]);
         list_add_tail(&rq->queuelist, &ad->fifo_list[data_dir]);
 
-        as_update_arq(ad, arq); /* keep state machine up to date */
-        arq->state = AS_RQ_QUEUED;
+        as_update_rq(ad, rq); /* keep state machine up to date */
+        RQ_SET_STATE(rq, AS_RQ_QUEUED);
 }
 
 static void as_activate_request(request_queue_t *q, struct request *rq)
 {
-        struct as_rq *arq = RQ_DATA(rq);
-
-        WARN_ON(arq->state != AS_RQ_DISPATCHED);
-        arq->state = AS_RQ_REMOVED;
-        if (arq->io_context && arq->io_context->aic)
-                atomic_dec(&arq->io_context->aic->nr_dispatched);
+        WARN_ON(RQ_STATE(rq) != AS_RQ_DISPATCHED);
+        RQ_SET_STATE(rq, AS_RQ_REMOVED);
+        if (RQ_IOC(rq) && RQ_IOC(rq)->aic)
+                atomic_dec(&RQ_IOC(rq)->aic->nr_dispatched);
 }
 
 static void as_deactivate_request(request_queue_t *q, struct request *rq)
 {
-        struct as_rq *arq = RQ_DATA(rq);
-
-        WARN_ON(arq->state != AS_RQ_REMOVED);
-        arq->state = AS_RQ_DISPATCHED;
-        if (arq->io_context && arq->io_context->aic)
-                atomic_inc(&arq->io_context->aic->nr_dispatched);
+        WARN_ON(RQ_STATE(rq) != AS_RQ_REMOVED);
+        RQ_SET_STATE(rq, AS_RQ_DISPATCHED);
+        if (RQ_IOC(rq) && RQ_IOC(rq)->aic)
+                atomic_inc(&RQ_IOC(rq)->aic->nr_dispatched);
 }
 
 /*
@@ -1237,8 +1223,8 @@ static void as_merged_request(request_queue_t *q, struct request *req, int type)
          * if the merge was a front merge, we need to reposition request
          */
         if (type == ELEVATOR_FRONT_MERGE) {
-                as_del_arq_rb(ad, req);
-                as_add_arq_rb(ad, req);
+                as_del_rq_rb(ad, req);
+                as_add_rq_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"
@@ -1250,25 +1236,22 @@ static void as_merged_request(request_queue_t *q, struct request *req, int type)
 static void as_merged_requests(request_queue_t *q, struct request *req,
                                 struct request *next)
 {
-        struct as_rq *arq = RQ_DATA(req);
-        struct as_rq *anext = RQ_DATA(next);
-
-        BUG_ON(!arq);
-        BUG_ON(!anext);
-
         /*
-         * if anext expires before arq, assign its expire time to arq
-         * and move into anext position (anext will be deleted) in fifo
+         * if next expires before rq, assign its expire time to arq
+         * and move into next position (next will be deleted) in fifo
          */
         if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
                 if (time_before(rq_fifo_time(next), rq_fifo_time(req))) {
+                        struct io_context *rioc = RQ_IOC(req);
+                        struct io_context *nioc = RQ_IOC(next);
+
                         list_move(&req->queuelist, &next->queuelist);
                         rq_set_fifo_time(req, rq_fifo_time(next));
                         /*
                          * Don't copy here but swap, because when anext is
                          * removed below, it must contain the unused context
                          */
-                        swap_io_context(&arq->io_context, &anext->io_context);
+                        swap_io_context(&rioc, &nioc);
                 }
         }
 
@@ -1276,9 +1259,9 @@ static void as_merged_requests(request_queue_t *q, struct request *req,
          * kill knowledge of next, this one is a goner
          */
         as_remove_queued_request(q, next);
-        as_put_io_context(anext);
+        as_put_io_context(next);
 
-        anext->state = AS_RQ_MERGED;
+        RQ_SET_STATE(next, AS_RQ_MERGED);
 }
 
 /*
@@ -1301,45 +1284,6 @@ static void as_work_handler(void *data)
         spin_unlock_irqrestore(q->queue_lock, flags);
 }
 
-static void as_put_request(request_queue_t *q, struct request *rq)
-{
-        struct as_data *ad = q->elevator->elevator_data;
-        struct as_rq *arq = RQ_DATA(rq);
-
-        if (!arq) {
-                WARN_ON(1);
-                return;
-        }
-
-        if (unlikely(arq->state != AS_RQ_POSTSCHED &&
-                     arq->state != AS_RQ_PRESCHED &&
-                     arq->state != AS_RQ_MERGED)) {
-                printk("arq->state %d\n", arq->state);
-                WARN_ON(1);
-        }
-
-        mempool_free(arq, ad->arq_pool);
-        rq->elevator_private = NULL;
-}
-
-static int as_set_request(request_queue_t *q, struct request *rq,
-                          struct bio *bio, gfp_t gfp_mask)
-{
-        struct as_data *ad = q->elevator->elevator_data;
-        struct as_rq *arq = mempool_alloc(ad->arq_pool, gfp_mask);
-
-        if (arq) {
-                memset(arq, 0, sizeof(*arq));
-                arq->request = rq;
-                arq->state = AS_RQ_PRESCHED;
-                arq->io_context = NULL;
-                rq->elevator_private = arq;
-                return 0;
-        }
-
-        return 1;
-}
-
 static int as_may_queue(request_queue_t *q, int rw, struct bio *bio)
 {
         int ret = ELV_MQUEUE_MAY;
@@ -1366,22 +1310,17 @@ static void as_exit_queue(elevator_t *e)
         BUG_ON(!list_empty(&ad->fifo_list[REQ_SYNC]));
         BUG_ON(!list_empty(&ad->fifo_list[REQ_ASYNC]));
 
-        mempool_destroy(ad->arq_pool);
         put_io_context(ad->io_context);
         kfree(ad);
 }
 
 /*
- * initialize elevator private data (as_data), and alloc a arq for
- * each request on the free lists
+ * initialize elevator private data (as_data).
  */
 static void *as_init_queue(request_queue_t *q, elevator_t *e)
 {
         struct as_data *ad;
 
-        if (!arq_pool)
-                return NULL;
-
         ad = kmalloc_node(sizeof(*ad), GFP_KERNEL, q->node);
         if (!ad)
                 return NULL;
@@ -1389,13 +1328,6 @@ static void *as_init_queue(request_queue_t *q, elevator_t *e)
 
         ad->q = q; /* Identify what queue the data belongs to */
 
-        ad->arq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
-                                mempool_free_slab, arq_pool, q->node);
-        if (!ad->arq_pool) {
-                kfree(ad);
-                return NULL;
-        }
-
         /* anticipatory scheduling helpers */
         ad->antic_timer.function = as_antic_timeout;
         ad->antic_timer.data = (unsigned long)q;
@@ -1516,8 +1448,6 @@ static struct elevator_type iosched_as = {
                 .elevator_completed_req_fn =    as_completed_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,
                 .elevator_init_fn =             as_init_queue,
                 .elevator_exit_fn =             as_exit_queue,
@@ -1533,11 +1463,6 @@ static int __init as_init(void)
 {
         int ret;
 
-        arq_pool = kmem_cache_create("as_arq", sizeof(struct as_rq),
-                                     0, 0, NULL, NULL);
-        if (!arq_pool)
-                return -ENOMEM;
-
         ret = elv_register(&iosched_as);
         if (!ret) {
                 /*
@@ -1549,7 +1474,6 @@ static int __init as_init(void)
                 return 0;
         }
 
-        kmem_cache_destroy(arq_pool);
         return ret;
 }
 
@@ -1563,7 +1487,6 @@ static void __exit as_exit(void)
         if (atomic_read(&ioc_count))
                 wait_for_completion(ioc_gone);
         synchronize_rcu();
-        kmem_cache_destroy(arq_pool);
 }
 
 module_init(as_init);