From: Nick Piggin <piggin@cyberone.com.au>
This fixes a bug in deadline and AS that causes insert_here to be ignored on
blk_fs_requests. This has been causing problems with SCSI requeueing code.
It makes elevator insertion more correct as advertised wrt insert_here and
REQ_SOFTBARRIER.
It also fixes a buglet in the as_requeue code where the request wasn't being
put into the front of the list (in rare cases).
drivers/block/as-iosched.c | 36 ++++++++++++++++++------------------
drivers/block/deadline-iosched.c | 16 ++++++++++------
drivers/block/elevator.c | 6 +++---
3 files changed, 31 insertions(+), 27 deletions(-)
diff -puN drivers/block/as-iosched.c~elv-insertion-fix drivers/block/as-iosched.c
--- 25/drivers/block/as-iosched.c~elv-insertion-fix 2003-09-01 11:13:29.000000000 -0700
+++ 25-akpm/drivers/block/as-iosched.c 2003-09-01 11:13:29.000000000 -0700
@@ -910,12 +910,7 @@ static void as_completed_request(request
struct as_rq *arq = RQ_DATA(rq);
struct as_io_context *aic;
- if (unlikely(!blk_fs_request(rq)))
- return;
-
- WARN_ON(blk_fs_request(rq) && arq->state == AS_RQ_NEW);
-
- if (arq->state != AS_RQ_DISPATCHED)
+ if (unlikely(arq->state != AS_RQ_DISPATCHED))
return;
if (ad->changed_batch && ad->nr_dispatched == 1) {
@@ -1035,7 +1030,7 @@ static void as_remove_request(request_qu
{
struct as_rq *arq = RQ_DATA(rq);
- if (unlikely(!blk_fs_request(rq)))
+ if (unlikely(arq->state == AS_RQ_NEW))
return;
if (!arq) {
@@ -1341,9 +1336,9 @@ static void as_requeue_request(request_q
atomic_inc(&arq->io_context->aic->nr_dispatched);
} else
WARN_ON(blk_fs_request(rq)
- && (!(rq->flags & REQ_HARDBARRIER)) );
+ && (!(rq->flags & (REQ_HARDBARRIER|REQ_SOFTBARRIER))) );
- list_add_tail(&rq->queuelist, ad->dispatch);
+ list_add(&rq->queuelist, ad->dispatch);
/* Stop anticipating - let this request get through */
as_antic_stop(ad);
@@ -1358,26 +1353,31 @@ as_insert_request(request_queue_t *q, st
struct as_data *ad = q->elevator.elevator_data;
struct as_rq *arq = RQ_DATA(rq);
- if (unlikely(rq->flags & REQ_HARDBARRIER)) {
+ if (unlikely(rq->flags & (REQ_HARDBARRIER|REQ_SOFTBARRIER))) {
q->last_merge = NULL;
- while (ad->next_arq[REQ_SYNC])
- as_move_to_dispatch(ad, ad->next_arq[REQ_SYNC]);
+ if (insert_here != ad->dispatch) {
+ while (ad->next_arq[REQ_SYNC])
+ as_move_to_dispatch(ad, ad->next_arq[REQ_SYNC]);
+
+ while (ad->next_arq[REQ_ASYNC])
+ as_move_to_dispatch(ad, ad->next_arq[REQ_ASYNC]);
+ }
- while (ad->next_arq[REQ_ASYNC])
- as_move_to_dispatch(ad, ad->next_arq[REQ_ASYNC]);
+ if (!insert_here)
+ insert_here = ad->dispatch->prev;
}
if (unlikely(!blk_fs_request(rq))) {
if (!insert_here)
- insert_here = ad->dispatch->prev;
+ insert_here = ad->dispatch;
+ }
+ if (insert_here) {
list_add(&rq->queuelist, insert_here);
/* Stop anticipating - let this request get through */
- if (!list_empty(ad->dispatch)
- && (ad->antic_status == ANTIC_WAIT_REQ
- || ad->antic_status == ANTIC_WAIT_NEXT))
+ if (list_empty(ad->dispatch))
as_antic_stop(ad);
return;
diff -puN drivers/block/deadline-iosched.c~elv-insertion-fix drivers/block/deadline-iosched.c
--- 25/drivers/block/deadline-iosched.c~elv-insertion-fix 2003-09-01 11:13:29.000000000 -0700
+++ 25-akpm/drivers/block/deadline-iosched.c 2003-09-01 11:13:29.000000000 -0700
@@ -627,21 +627,25 @@ deadline_insert_request(request_queue_t
struct deadline_data *dd = q->elevator.elevator_data;
struct deadline_rq *drq = RQ_DATA(rq);
- if (unlikely(rq->flags & REQ_HARDBARRIER)) {
+ if (unlikely(rq->flags & (REQ_HARDBARRIER|REQ_SOFTBARRIER))) {
DL_INVALIDATE_HASH(dd);
q->last_merge = NULL;
- while (deadline_dispatch_requests(dd))
- ;
+ if (insert_here != dd->dispatch) {
+ while (deadline_dispatch_requests(dd))
+ ;
+ }
- list_add_tail(&rq->queuelist, dd->dispatch);
- return;
+ if (!insert_here)
+ insert_here = dd->dispatch->prev;
}
if (unlikely(!blk_fs_request(rq))) {
if (!insert_here)
- insert_here = dd->dispatch->prev;
+ insert_here = dd->dispatch;
+ }
+ if (insert_here) {
list_add(&rq->queuelist, insert_here);
return;
}
diff -puN drivers/block/elevator.c~elv-insertion-fix drivers/block/elevator.c
--- 25/drivers/block/elevator.c~elv-insertion-fix 2003-09-01 11:13:29.000000000 -0700
+++ 25-akpm/drivers/block/elevator.c 2003-09-01 11:13:29.000000000 -0700
@@ -162,10 +162,10 @@ void elv_requeue_request(request_queue_t
void __elv_add_request(request_queue_t *q, struct request *rq, int at_end,
int plug)
{
- struct list_head *insert = &q->queue_head;
+ struct list_head *insert = NULL;
- if (at_end)
- insert = insert->prev;
+ if (!at_end)
+ insert = &q->queue_head;
if (plug)
blk_plug_device(q);
_