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Date: Fri, 28 Nov 2008 13:32:04 +0900
From: Tejun Heo <tj@...nel.org>
To: jens.axboe@...cle.com, linux-kernel@...r.kernel.org
Cc: Tejun Heo <tj@...nel.org>
Subject: [PATCH 3/6] block: make every barrier action optional
In all barrier sequences, the barrier write itself was always assumed
to be issued and thus didn't have corresponding control flag. This
patch adds QUEUE_ORDERED_DO_BAR and unify action mask handling in
start_ordered() such that any barrier action can be skipped.
This patch doesn't introduce any visible behavior changes.
Signed-off-by: Tejun Heo <tj@...nel.org>
---
block/blk-barrier.c | 41 ++++++++++++++++++++++++-----------------
include/linux/blkdev.h | 7 +++++--
2 files changed, 29 insertions(+), 19 deletions(-)
diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index 43d479a..1efabf8 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -158,19 +158,10 @@ static inline struct request *start_ordered(struct request_queue *q,
q->ordered = q->next_ordered;
q->ordseq |= QUEUE_ORDSEQ_STARTED;
- /*
- * Prep proxy barrier request.
- */
+ /* stash away the original request */
elv_dequeue_request(q, rq);
q->orig_bar_rq = rq;
- rq = &q->bar_rq;
- blk_rq_init(q, rq);
- if (bio_data_dir(q->orig_bar_rq->bio) == WRITE)
- rq->cmd_flags |= REQ_RW;
- if (q->ordered & QUEUE_ORDERED_DO_FUA)
- rq->cmd_flags |= REQ_FUA;
- init_request_from_bio(rq, q->orig_bar_rq->bio);
- rq->end_io = bar_end_io;
+ rq = NULL;
/*
* Queue ordered sequence. As we stack them at the head, we
@@ -181,12 +172,28 @@ static inline struct request *start_ordered(struct request_queue *q,
* there will be no data written between the pre and post flush.
* Hence a single flush will suffice.
*/
- if ((q->ordered & QUEUE_ORDERED_DO_POSTFLUSH) && !blk_empty_barrier(rq))
+ if ((q->ordered & QUEUE_ORDERED_DO_POSTFLUSH) &&
+ !blk_empty_barrier(q->orig_bar_rq)) {
queue_flush(q, QUEUE_ORDERED_DO_POSTFLUSH);
- else
+ rq = &q->post_flush_rq;
+ } else
q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH;
- elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
+ if (q->ordered & QUEUE_ORDERED_DO_BAR) {
+ rq = &q->bar_rq;
+
+ /* initialize proxy request and queue it */
+ blk_rq_init(q, rq);
+ if (bio_data_dir(q->orig_bar_rq->bio) == WRITE)
+ rq->cmd_flags |= REQ_RW;
+ if (q->ordered & QUEUE_ORDERED_DO_FUA)
+ rq->cmd_flags |= REQ_FUA;
+ init_request_from_bio(rq, q->orig_bar_rq->bio);
+ rq->end_io = bar_end_io;
+
+ elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
+ } else
+ q->ordseq |= QUEUE_ORDSEQ_BAR;
if (q->ordered & QUEUE_ORDERED_DO_PREFLUSH) {
queue_flush(q, QUEUE_ORDERED_DO_PREFLUSH);
@@ -194,10 +201,10 @@ static inline struct request *start_ordered(struct request_queue *q,
} else
q->ordseq |= QUEUE_ORDSEQ_PREFLUSH;
- if ((q->ordered & QUEUE_ORDERED_BY_TAG) || q->in_flight == 0)
- q->ordseq |= QUEUE_ORDSEQ_DRAIN;
- else
+ if ((q->ordered & QUEUE_ORDERED_BY_DRAIN) && q->in_flight)
rq = NULL;
+ else
+ q->ordseq |= QUEUE_ORDSEQ_DRAIN;
return rq;
}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 7f9cd08..076620d 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -526,12 +526,14 @@ enum {
QUEUE_ORDERED_BY_DRAIN = 0x01,
QUEUE_ORDERED_BY_TAG = 0x02,
QUEUE_ORDERED_DO_PREFLUSH = 0x10,
+ QUEUE_ORDERED_DO_BAR = 0x20,
QUEUE_ORDERED_DO_POSTFLUSH = 0x40,
QUEUE_ORDERED_DO_FUA = 0x80,
QUEUE_ORDERED_NONE = 0x00,
- QUEUE_ORDERED_DRAIN = QUEUE_ORDERED_BY_DRAIN,
+ QUEUE_ORDERED_DRAIN = QUEUE_ORDERED_BY_DRAIN |
+ QUEUE_ORDERED_DO_BAR,
QUEUE_ORDERED_DRAIN_FLUSH = QUEUE_ORDERED_DRAIN |
QUEUE_ORDERED_DO_PREFLUSH |
QUEUE_ORDERED_DO_POSTFLUSH,
@@ -539,7 +541,8 @@ enum {
QUEUE_ORDERED_DO_PREFLUSH |
QUEUE_ORDERED_DO_FUA,
- QUEUE_ORDERED_TAG = QUEUE_ORDERED_BY_TAG,
+ QUEUE_ORDERED_TAG = QUEUE_ORDERED_BY_TAG |
+ QUEUE_ORDERED_DO_BAR,
QUEUE_ORDERED_TAG_FLUSH = QUEUE_ORDERED_TAG |
QUEUE_ORDERED_DO_PREFLUSH |
QUEUE_ORDERED_DO_POSTFLUSH,
--
1.5.6
--
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