03_blk_generic-last_merge-handling.patch
Currently, both generic elevator code and specific ioscheds
participate in the management and usage of last_merge. This
and the following patches move last_merge handling into
generic elevator code.
Signed-off-by: Tejun Heo <[email protected]>
elevator.c | 43 ++++++++++++++++++-------------------------
1 files changed, 18 insertions(+), 25 deletions(-)
Index: blk-fixes/drivers/block/elevator.c
===================================================================
--- blk-fixes.orig/drivers/block/elevator.c 2005-07-26 22:55:00.000000000 +0900
+++ blk-fixes/drivers/block/elevator.c 2005-07-26 22:55:00.000000000 +0900
@@ -88,15 +88,6 @@ inline int elv_try_merge(struct request
}
EXPORT_SYMBOL(elv_try_merge);
-inline int elv_try_last_merge(request_queue_t *q, struct bio *bio)
-{
- if (q->last_merge)
- return elv_try_merge(q->last_merge, bio);
-
- return ELEVATOR_NO_MERGE;
-}
-EXPORT_SYMBOL(elv_try_last_merge);
-
static struct elevator_type *elevator_find(const char *name)
{
struct elevator_type *e = NULL;
@@ -244,6 +235,9 @@ void elv_dispatch_insert(request_queue_t
unsigned max_back;
struct list_head *entry;
+ if (q->last_merge == rq)
+ q->last_merge = NULL;
+
if (!sort) {
/* Specific elevator is performing sort. Step away. */
q->last_sector = rq_last_sector(rq);
@@ -278,6 +272,15 @@ void elv_dispatch_insert(request_queue_t
int elv_merge(request_queue_t *q, struct request **req, struct bio *bio)
{
elevator_t *e = q->elevator;
+ int ret;
+
+ if (q->last_merge) {
+ ret = elv_try_merge(q->last_merge, bio);
+ if (ret != ELEVATOR_NO_MERGE) {
+ *req = q->last_merge;
+ return ret;
+ }
+ }
if (e->ops->elevator_merge_fn)
return e->ops->elevator_merge_fn(q, req, bio);
@@ -291,6 +294,8 @@ void elv_merged_request(request_queue_t
if (e->ops->elevator_merged_fn)
e->ops->elevator_merged_fn(q, rq);
+
+ q->last_merge = rq;
}
void elv_merge_requests(request_queue_t *q, struct request *rq,
@@ -298,11 +303,10 @@ void elv_merge_requests(request_queue_t
{
elevator_t *e = q->elevator;
- if (q->last_merge == next)
- q->last_merge = NULL;
-
if (e->ops->elevator_merge_req_fn)
e->ops->elevator_merge_req_fn(q, rq, next);
+
+ q->last_merge = rq;
}
void elv_requeue_request(request_queue_t *q, struct request *rq)
@@ -397,6 +401,8 @@ void __elv_add_request(request_queue_t *
BUG_ON(!blk_fs_request(rq));
rq->flags |= REQ_SORTED;
q->elevator->ops->elevator_add_req_fn(q, rq);
+ if (q->last_merge == NULL && rq_mergeable(rq))
+ q->last_merge = rq;
break;
default:
@@ -475,9 +481,6 @@ struct request *elv_next_request(request
rq->flags |= REQ_STARTED;
}
- if (rq == q->last_merge)
- q->last_merge = NULL;
-
if (!q->boundary_rq || q->boundary_rq == rq) {
q->last_sector = rq_last_sector(rq);
q->boundary_rq = NULL;
@@ -531,16 +534,6 @@ void elv_dequeue_request(request_queue_t
*/
if (blk_account_rq(rq))
q->in_flight++;
-
- /*
- * the main clearing point for q->last_merge is on retrieval of
- * request by driver (it calls elv_next_request()), but it _can_
- * also happen here if a request is added to the queue but later
- * deleted without ever being given to driver (merged with another
- * request).
- */
- if (rq == q->last_merge)
- q->last_merge = NULL;
}
int elv_queue_empty(request_queue_t *q)
-
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