| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Wed, 30 Mar 2011 12:16:13 +0200
From: Jens Axboe <axboe@...nel.dk>
To: Tejun Heo <tj@...nel.org>
CC: Vivek Goyal <vgoyal@...hat.com>, Jeff Moyer <jmoyer@...hat.com>,
Mike Snitzer <snitzer@...hat.com>,
Markus Trippelsdorf <markus@...ppelsdorf.de>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
linux-kernel@...r.kernel.org, Chris Mason <chris.mason@...cle.com>
Subject: Re: [PATCH] block: eliminate ELEVATOR_INSERT_REQUEUE
On 2011-03-30 10:02, Tejun Heo wrote:
> Hello, Jens.
>
> On Wed, Mar 30, 2011 at 09:59:09AM +0200, Jens Axboe wrote:
>> Pure front insert should be used for requeue and internal commands (like
>> spin up this drive, or get error information). Flush should append to
>> the dispatch list.
>
> Yeah, right. The reason I used REQUEUE/FRONT was because BACK
> insertion involves draining the elevator and then appending the
> request at the end of the dispatch queue, which is unnecessary and
> inefficient. So, front insertion was a quick work around that. If
> we're removing elv_insert(), we can just append directly to the
> dispatch queue from flush code.
How does this look? It's really two patches, but rolled up into one for
easier posting here.
diff --git a/block/blk-flush.c b/block/blk-flush.c
index 93d5fd8..6a16fea 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -261,7 +261,7 @@ static bool blk_kick_flush(struct request_queue *q)
q->flush_rq.end_io = flush_end_io;
q->flush_pending_idx ^= 1;
- elv_insert(q, &q->flush_rq, ELEVATOR_INSERT_REQUEUE);
+ __elv_add_request(q, &q->flush_rq, ELEVATOR_INSERT_FLUSH);
return true;
}
@@ -281,7 +281,7 @@ static void flush_data_end_io(struct request *rq, int error)
* blk_insert_flush - insert a new FLUSH/FUA request
* @rq: request to insert
*
- * To be called from elv_insert() for %ELEVATOR_INSERT_FLUSH insertions.
+ * To be called from __elv_add_request() for %ELEVATOR_INSERT_FLUSH insertions.
* @rq is being submitted. Analyze what needs to be done and put it on the
* right queue.
*
@@ -312,7 +312,7 @@ void blk_insert_flush(struct request *rq)
*/
if ((policy & REQ_FSEQ_DATA) &&
!(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) {
- list_add(&rq->queuelist, &q->queue_head);
+ list_add_tail(&rq->queuelist, &q->queue_head);
return;
}
diff --git a/block/elevator.c b/block/elevator.c
index c387d31..0cdb4e7 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -610,7 +610,7 @@ void elv_requeue_request(struct request_queue *q, struct request *rq)
rq->cmd_flags &= ~REQ_STARTED;
- elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE);
+ __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE);
}
void elv_drain_elevator(struct request_queue *q)
@@ -655,12 +655,25 @@ void elv_quiesce_end(struct request_queue *q)
queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
}
-void elv_insert(struct request_queue *q, struct request *rq, int where)
+void __elv_add_request(struct request_queue *q, struct request *rq, int where)
{
trace_block_rq_insert(q, rq);
rq->q = q;
+ BUG_ON(rq->cmd_flags & REQ_ON_PLUG);
+
+ if (rq->cmd_flags & REQ_SOFTBARRIER) {
+ /* barriers are scheduling boundary, update end_sector */
+ if (rq->cmd_type == REQ_TYPE_FS ||
+ (rq->cmd_flags & REQ_DISCARD)) {
+ q->end_sector = rq_end_sector(rq);
+ q->boundary_rq = rq;
+ }
+ } else if (!(rq->cmd_flags & REQ_ELVPRIV) &&
+ where == ELEVATOR_INSERT_SORT)
+ where = ELEVATOR_INSERT_BACK;
+
switch (where) {
case ELEVATOR_INSERT_REQUEUE:
case ELEVATOR_INSERT_FRONT:
@@ -722,24 +735,6 @@ void elv_insert(struct request_queue *q, struct request *rq, int where)
BUG();
}
}
-
-void __elv_add_request(struct request_queue *q, struct request *rq, int where)
-{
- BUG_ON(rq->cmd_flags & REQ_ON_PLUG);
-
- if (rq->cmd_flags & REQ_SOFTBARRIER) {
- /* barriers are scheduling boundary, update end_sector */
- if (rq->cmd_type == REQ_TYPE_FS ||
- (rq->cmd_flags & REQ_DISCARD)) {
- q->end_sector = rq_end_sector(rq);
- q->boundary_rq = rq;
- }
- } else if (!(rq->cmd_flags & REQ_ELVPRIV) &&
- where == ELEVATOR_INSERT_SORT)
- where = ELEVATOR_INSERT_BACK;
-
- elv_insert(q, rq, where);
-}
EXPORT_SYMBOL(__elv_add_request);
void elv_add_request(struct request_queue *q, struct request *rq, int where)
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index d93efcc445..21a8ebf 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -101,7 +101,6 @@ extern void elv_dispatch_sort(struct request_queue *, struct request *);
extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
extern void elv_add_request(struct request_queue *, struct request *, int);
extern void __elv_add_request(struct request_queue *, struct request *, int);
-extern void elv_insert(struct request_queue *, struct request *, int);
extern int elv_merge(struct request_queue *, struct request **, struct bio *);
extern int elv_try_merge(struct request *, struct bio *);
extern void elv_merge_requests(struct request_queue *, struct request *,
--
Jens Axboe
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists