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Date: Thu, 26 Mar 2009 16:53:24 +0100
From: Jerome Marchand <jmarchan@...hat.com>
To: Jens Axboe <jens.axboe@...cle.com>
CC: linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 2/2] block: fix inconsistency in I/O stat accounting code
This forces in_flight to be zero when turning off or on the I/O stat
accounting and stops updating I/O stats in attempt_merge() when
accounting is turned off.
Signed-off-by: Jerome Marchand <jmarchan@...hat.com>
---
block/blk-core.c | 13 ++++---------
block/blk-merge.c | 29 +++++++++++++++++------------
block/blk-sysfs.c | 4 ++++
block/blk.h | 10 ++++++----
block/elevator.c | 2 +-
include/linux/elevator.h | 1 +
6 files changed, 33 insertions(+), 26 deletions(-)
Index: linux-2.6/block/blk-core.c
===================================================================
--- linux-2.6.orig/block/blk-core.c
+++ linux-2.6/block/blk-core.c
@@ -64,12 +64,11 @@ static struct workqueue_struct *kblockd_
static void drive_stat_acct(struct request *rq, int new_io)
{
- struct gendisk *disk = rq->rq_disk;
struct hd_struct *part;
int rw = rq_data_dir(rq);
int cpu;
- if (!blk_fs_request(rq) || !disk || !blk_do_io_stat(disk->queue))
+ if (!blk_fs_request(rq) || !blk_do_io_stat(rq))
return;
cpu = part_stat_lock();
@@ -1665,9 +1664,7 @@ EXPORT_SYMBOL(blkdev_dequeue_request);
static void blk_account_io_completion(struct request *req, unsigned int
bytes)
{
- struct gendisk *disk = req->rq_disk;
-
- if (!disk || !blk_do_io_stat(disk->queue))
+ if (!blk_do_io_stat(req))
return;
if (blk_fs_request(req)) {
@@ -1684,9 +1681,7 @@ static void blk_account_io_completion(st
static void blk_account_io_done(struct request *req)
{
- struct gendisk *disk = req->rq_disk;
-
- if (!disk || !blk_do_io_stat(disk->queue))
+ if (!blk_do_io_stat(req))
return;
/*
@@ -1701,7 +1696,7 @@ static void blk_account_io_done(struct r
int cpu;
cpu = part_stat_lock();
- part = disk_map_sector_rcu(disk, req->sector);
+ part = disk_map_sector_rcu(req->rq_disk, req->sector);
part_stat_inc(cpu, part, ios[rw]);
part_stat_add(cpu, part, ticks[rw], duration);
Index: linux-2.6/block/blk-merge.c
===================================================================
--- linux-2.6.orig/block/blk-merge.c
+++ linux-2.6/block/blk-merge.c
@@ -338,6 +338,22 @@ static int ll_merge_requests_fn(struct r
return 1;
}
+static void blk_account_io_merge(struct request *req)
+{
+ if (blk_do_io_stat(req)) {
+ struct hd_struct *part;
+ int cpu;
+
+ cpu = part_stat_lock();
+ part = disk_map_sector_rcu(req->rq_disk, req->sector);
+
+ part_round_stats(cpu, part);
+ part_dec_in_flight(part);
+
+ part_stat_unlock();
+ }
+}
+
/*
* Has to be called with the request spinlock acquired
*/
@@ -386,18 +402,7 @@ static int attempt_merge(struct request_
elv_merge_requests(q, req, next);
- if (req->rq_disk) {
- struct hd_struct *part;
- int cpu;
-
- cpu = part_stat_lock();
- part = disk_map_sector_rcu(req->rq_disk, req->sector);
-
- part_round_stats(cpu, part);
- part_dec_in_flight(part);
-
- part_stat_unlock();
- }
+ blk_account_io_merge(req);
req->ioprio = ioprio_best(req->ioprio, next->ioprio);
if (blk_rq_cpu_valid(next))
Index: linux-2.6/block/blk-sysfs.c
===================================================================
--- linux-2.6.orig/block/blk-sysfs.c
+++ linux-2.6/block/blk-sysfs.c
@@ -209,10 +209,14 @@ static ssize_t queue_iostats_store(struc
ssize_t ret = queue_var_store(&stats, page, count);
spin_lock_irq(q->queue_lock);
+ elv_quisce_start(q);
+
if (stats)
queue_flag_set(QUEUE_FLAG_IO_STAT, q);
else
queue_flag_clear(QUEUE_FLAG_IO_STAT, q);
+
+ elv_quisce_end(q);
spin_unlock_irq(q->queue_lock);
return ret;
Index: linux-2.6/block/blk.h
===================================================================
--- linux-2.6.orig/block/blk.h
+++ linux-2.6/block/blk.h
@@ -112,12 +112,14 @@ static inline int blk_cpu_to_group(int c
#endif
}
-static inline int blk_do_io_stat(struct request_queue *q)
+static inline int blk_do_io_stat(struct request *rq)
{
- if (q)
- return blk_queue_io_stat(q);
+ struct gendisk *disk = rq->rq_disk;
- return 0;
+ if (!disk || !disk->queue)
+ return 0;
+
+ return blk_queue_io_stat(disk->queue) && (rq->cmd_flags & REQ_ELVPRIV);
}
#endif
Index: linux-2.6/block/elevator.c
===================================================================
--- linux-2.6.orig/block/elevator.c
+++ linux-2.6/block/elevator.c
@@ -573,7 +573,7 @@ void elv_requeue_request(struct request_
elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE);
}
-static void elv_drain_elevator(struct request_queue *q)
+void elv_drain_elevator(struct request_queue *q)
{
static int printed;
while (q->elevator->ops->elevator_dispatch_fn(q, 1))
Index: linux-2.6/include/linux/elevator.h
===================================================================
--- linux-2.6.orig/include/linux/elevator.h
+++ linux-2.6/include/linux/elevator.h
@@ -116,6 +116,7 @@ extern void elv_abort_queue(struct reque
extern void elv_completed_request(struct request_queue *, struct
request *);
extern int elv_set_request(struct request_queue *, struct request *,
gfp_t);
extern void elv_put_request(struct request_queue *, struct request *);
+extern void elv_drain_elevator(struct request_queue *);
/*
* io scheduler registration
--
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