[PATCH 09/11] block: add q->nr_rqs[] and move q->rq.elvpriv to q->nr_rqs_elvpriv

Tejun Heo
2012-04-26T22:00:04Z

Add q->nr_rqs[] which currently behaves the same as q->rq.count[] and
move q->rq.elvpriv to q->nr_rqs_elvpriv. blk_drain_queue() is updated
to use q->nr_rqs[] instead of q->rq.count[].

These counters separates queue-wide request statistics from the
request list and allow implementation of per-queue request allocation.

While at it, properly indent fields of struct request_list.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
block/blk-core.c | 13 +++++++------
include/linux/blkdev.h | 11 ++++++-----
2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 242bf9e..7377eb6 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -386,7 +386,7 @@ void blk_drain_queue(struct request_queue *q, bool drain_all)
if (!list_empty(&q->queue_head) && q->request_fn)
__blk_run_queue(q);

- drain |= q->rq.elvpriv;
+ drain |= q->nr_rqs_elvpriv;

/*
* Unfortunately, requests are queued at and tracked from
@@ -396,7 +396,7 @@ void blk_drain_queue(struct request_queue *q, bool drain_all)
if (drain_all) {
drain |= !list_empty(&q->queue_head);
for (i = 0; i < 2; i++) {
- drain |= q->rq.count[i];
+ drain |= q->nr_rqs[i];
drain |= q->in_flight[i];
drain |= !list_empty(&q->flush_queue[i]);
}
@@ -513,7 +513,6 @@ static int blk_init_free_list(struct request_queue *q)

rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
- rl->elvpriv = 0;
init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);

@@ -778,9 +777,10 @@ static void freed_request(struct request_queue *q, unsigned int flags)
struct request_list *rl = &q->rq;
int sync = rw_is_sync(flags);

+ q->nr_rqs[sync]--;
rl->count[sync]--;
if (flags & REQ_ELVPRIV)
- rl->elvpriv--;
+ q->nr_rqs_elvpriv--;

__freed_request(q, sync);

@@ -889,6 +889,7 @@ static struct request *__get_request(struct request_queue *q, int rw_flags,
if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
return NULL;

+ q->nr_rqs[is_sync]++;
rl->count[is_sync]++;
rl->starved[is_sync] = 0;

@@ -904,7 +905,7 @@ static struct request *__get_request(struct request_queue *q, int rw_flags,
*/
if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) {
rw_flags |= REQ_ELVPRIV;
- rl->elvpriv++;
+ q->nr_rqs_elvpriv++;
if (et->icq_cache && ioc)
icq = ioc_lookup_icq(ioc, q);
}
@@ -965,7 +966,7 @@ fail_elvpriv:
rq->elv.icq = NULL;

spin_lock_irq(q->queue_lock);
- rl->elvpriv--;
+ q->nr_rqs_elvpriv--;
spin_unlock_irq(q->queue_lock);
goto out;

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index af33fb1..b085be7 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -50,11 +50,10 @@ struct request_list {
* count[], starved[], and wait[] are indexed by
* BLK_RW_SYNC/BLK_RW_ASYNC
*/
- int count[2];
- int starved[2];
- int elvpriv;
- mempool_t *rq_pool;
- wait_queue_head_t wait[2];
+ int count[2];
+ int starved[2];
+ mempool_t *rq_pool;
+ wait_queue_head_t wait[2];
};

/*
@@ -281,6 +280,8 @@ struct request_queue {
struct list_head queue_head;
struct request *last_merge;
struct elevator_queue *elevator;
+ int nr_rqs[2]; /* # allocated [a]sync rqs */
+ int nr_rqs_elvpriv; /* # allocated rqs w/ elvpriv */

/*
* the queue request freelist, one for reads and one for writes
--
1.7.7.3