04_blk_generic-last_merge-handling-update-for-ioscheds.patch

        Remove last_merge handling from all ioscheds.  This patch
        removes merging capability of noop iosched.

Signed-off-by: Tejun Heo <[EMAIL PROTECTED]>

 as-iosched.c       |   35 ++++-------------------------------
 cfq-iosched.c      |   19 +------------------
 deadline-iosched.c |   30 ++----------------------------
 noop-iosched.c     |   31 -------------------------------
 4 files changed, 7 insertions(+), 108 deletions(-)

Index: blk-fixes/drivers/block/as-iosched.c
===================================================================
--- blk-fixes.orig/drivers/block/as-iosched.c   2005-07-26 22:55:00.000000000 
+0900
+++ blk-fixes/drivers/block/as-iosched.c        2005-07-26 22:55:01.000000000 
+0900
@@ -279,14 +279,6 @@ static inline void as_del_arq_hash(struc
                __as_del_arq_hash(arq);
 }
 
-static void as_remove_merge_hints(request_queue_t *q, struct as_rq *arq)
-{
-       as_del_arq_hash(arq);
-
-       if (q->last_merge == arq->request)
-               q->last_merge = NULL;
-}
-
 static void as_add_arq_hash(struct as_data *ad, struct as_rq *arq)
 {
        struct request *rq = arq->request;
@@ -330,7 +322,7 @@ static struct request *as_find_arq_hash(
                BUG_ON(!arq->on_hash);
 
                if (!rq_mergeable(__rq)) {
-                       as_remove_merge_hints(ad->q, arq);
+                       as_del_arq_hash(arq);
                        continue;
                }
 
@@ -1040,7 +1032,7 @@ static void as_remove_queued_request(req
                ad->next_arq[data_dir] = as_find_next_arq(ad, arq);
 
        list_del_init(&arq->fifo);
-       as_remove_merge_hints(q, arq);
+       as_del_arq_hash(arq);
        as_del_arq_rb(ad, arq);
 }
 
@@ -1351,7 +1343,7 @@ as_add_aliased_request(struct as_data *a
        /*
         * Don't want to have to handle merges.
         */
-       as_remove_merge_hints(ad->q, arq);
+       as_del_arq_hash(arq);
 }
 
 /*
@@ -1392,12 +1384,8 @@ static void as_add_request(request_queue
                arq->expires = jiffies + ad->fifo_expire[data_dir];
                list_add_tail(&arq->fifo, &ad->fifo_list[data_dir]);
 
-               if (rq_mergeable(arq->request)) {
+               if (rq_mergeable(arq->request))
                        as_add_arq_hash(ad, arq);
-
-                       if (!ad->q->last_merge)
-                               ad->q->last_merge = arq->request;
-               }
                as_update_arq(ad, arq); /* keep state machine up to date */
 
        } else {
@@ -1487,15 +1475,6 @@ as_merge(request_queue_t *q, struct requ
        int ret;
 
        /*
-        * try last_merge to avoid going to hash
-        */
-       ret = elv_try_last_merge(q, bio);
-       if (ret != ELEVATOR_NO_MERGE) {
-               __rq = q->last_merge;
-               goto out_insert;
-       }
-
-       /*
         * see if the merge hash can satisfy a back merge
         */
        __rq = as_find_arq_hash(ad, bio->bi_sector);
@@ -1523,9 +1502,6 @@ as_merge(request_queue_t *q, struct requ
 
        return ELEVATOR_NO_MERGE;
 out:
-       if (rq_mergeable(__rq))
-               q->last_merge = __rq;
-out_insert:
        if (ret) {
                if (rq_mergeable(__rq))
                        as_hot_arq_hash(ad, RQ_DATA(__rq));
@@ -1572,9 +1548,6 @@ static void as_merged_request(request_qu
                 * behind the disk head. We currently don't bother adjusting.
                 */
        }
-
-       if (arq->on_hash)
-               q->last_merge = req;
 }
 
 static void
Index: blk-fixes/drivers/block/cfq-iosched.c
===================================================================
--- blk-fixes.orig/drivers/block/cfq-iosched.c  2005-07-26 22:55:00.000000000 
+0900
+++ blk-fixes/drivers/block/cfq-iosched.c       2005-07-26 22:55:01.000000000 
+0900
@@ -648,8 +648,6 @@ static void cfq_remove_request(struct re
        list_del_init(&rq->queuelist);
        cfq_del_crq_rb(crq);
        cfq_del_crq_hash(crq);
-       if (rq->q->last_merge == crq->request)
-               rq->q->last_merge = NULL;
 }
 
 static int
@@ -659,12 +657,6 @@ cfq_merge(request_queue_t *q, struct req
        struct request *__rq;
        int ret;
 
-       ret = elv_try_last_merge(q, bio);
-       if (ret != ELEVATOR_NO_MERGE) {
-               __rq = q->last_merge;
-               goto out_insert;
-       }
-
        __rq = cfq_find_rq_hash(cfqd, bio->bi_sector);
        if (__rq) {
                BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector);
@@ -685,8 +677,6 @@ cfq_merge(request_queue_t *q, struct req
 
        return ELEVATOR_NO_MERGE;
 out:
-       q->last_merge = __rq;
-out_insert:
        *req = __rq;
        return ret;
 }
@@ -705,8 +695,6 @@ static void cfq_merged_request(request_q
                cfq_update_next_crq(crq);
                cfq_reposition_crq_rb(cfqq, crq);
        }
-
-       q->last_merge = req;
 }
 
 static void
@@ -1127,12 +1115,8 @@ cfq_insert_request(request_queue_t *q, s
 
        list_add_tail(&crq->request->queuelist, 
&crq->cfq_queue->fifo[crq->is_sync]);
 
-       if (rq_mergeable(rq)) {
+       if (rq_mergeable(rq))
                cfq_add_crq_hash(cfqd, crq);
-
-               if (!q->last_merge)
-                       q->last_merge = rq;
-       }
 }
 
 static int cfq_queue_empty(request_queue_t *q)
@@ -1251,7 +1235,6 @@ static void cfq_put_request(request_queu
        struct cfq_rq *crq = RQ_DATA(rq);
        struct cfq_queue *cfqq = crq->cfq_queue;
 
-       BUG_ON(q->last_merge == rq);
        BUG_ON(!hlist_unhashed(&crq->hash));
 
        if (crq->io_context)
Index: blk-fixes/drivers/block/deadline-iosched.c
===================================================================
--- blk-fixes.orig/drivers/block/deadline-iosched.c     2005-07-26 
22:55:00.000000000 +0900
+++ blk-fixes/drivers/block/deadline-iosched.c  2005-07-26 22:55:01.000000000 
+0900
@@ -112,15 +112,6 @@ static inline void deadline_del_drq_hash
                __deadline_del_drq_hash(drq);
 }
 
-static void
-deadline_remove_merge_hints(request_queue_t *q, struct deadline_rq *drq)
-{
-       deadline_del_drq_hash(drq);
-
-       if (q->last_merge == drq->request)
-               q->last_merge = NULL;
-}
-
 static inline void
 deadline_add_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
 {
@@ -299,12 +290,8 @@ deadline_add_request(struct request_queu
        drq->expires = jiffies + dd->fifo_expire[data_dir];
        list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]);
 
-       if (rq_mergeable(rq)) {
+       if (rq_mergeable(rq))
                deadline_add_drq_hash(dd, drq);
-
-               if (!q->last_merge)
-                       q->last_merge = rq;
-       }
 }
 
 /*
@@ -316,8 +303,8 @@ static void deadline_remove_request(requ
        struct deadline_data *dd = q->elevator->elevator_data;
 
        list_del_init(&drq->fifo);
-       deadline_remove_merge_hints(q, drq);
        deadline_del_drq_rb(dd, drq);
+       deadline_del_drq_hash(drq);
 }
 
 static int
@@ -328,15 +315,6 @@ deadline_merge(request_queue_t *q, struc
        int ret;
 
        /*
-        * try last_merge to avoid going to hash
-        */
-       ret = elv_try_last_merge(q, bio);
-       if (ret != ELEVATOR_NO_MERGE) {
-               __rq = q->last_merge;
-               goto out_insert;
-       }
-
-       /*
         * see if the merge hash can satisfy a back merge
         */
        __rq = deadline_find_drq_hash(dd, bio->bi_sector);
@@ -368,8 +346,6 @@ deadline_merge(request_queue_t *q, struc
 
        return ELEVATOR_NO_MERGE;
 out:
-       q->last_merge = __rq;
-out_insert:
        if (ret)
                deadline_hot_drq_hash(dd, RQ_DATA(__rq));
        *req = __rq;
@@ -394,8 +370,6 @@ static void deadline_merged_request(requ
                deadline_del_drq_rb(dd, drq);
                deadline_add_drq_rb(dd, drq);
        }
-
-       q->last_merge = req;
 }
 
 static void
Index: blk-fixes/drivers/block/noop-iosched.c
===================================================================
--- blk-fixes.orig/drivers/block/noop-iosched.c 2005-07-26 22:55:00.000000000 
+0900
+++ blk-fixes/drivers/block/noop-iosched.c      2005-07-26 22:55:01.000000000 
+0900
@@ -7,38 +7,9 @@
 #include <linux/module.h>
 #include <linux/init.h>
 
-/*
- * See if we can find a request that this buffer can be coalesced with.
- */
-static int elevator_noop_merge(request_queue_t *q, struct request **req,
-                              struct bio *bio)
-{
-       int ret;
-
-       ret = elv_try_last_merge(q, bio);
-       if (ret != ELEVATOR_NO_MERGE)
-               *req = q->last_merge;
-
-       return ret;
-}
-
-static void elevator_noop_merge_requests(request_queue_t *q, struct request 
*req,
-                                        struct request *next)
-{
-       list_del_init(&next->queuelist);
-}
-
 static void elevator_noop_add_request(request_queue_t *q, struct request *rq)
 {
        elv_dispatch_insert(q, rq, 0);
-
-       /*
-        * new merges must not precede this barrier
-        */
-       if (rq->flags & REQ_HARDBARRIER)
-               q->last_merge = NULL;
-       else if (!q->last_merge)
-               q->last_merge = rq;
 }
 
 static int elevator_noop_dispatch(request_queue_t *q, int force)
@@ -48,8 +19,6 @@ static int elevator_noop_dispatch(reques
 
 static struct elevator_type elevator_noop = {
        .ops = {
-               .elevator_merge_fn              = elevator_noop_merge,
-               .elevator_merge_req_fn          = elevator_noop_merge_requests,
                .elevator_dispatch_fn           = elevator_noop_dispatch,
                .elevator_add_req_fn            = elevator_noop_add_request,
        },

-
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