Commit 74672d06 authored Apr 03, 2015 by Gu Zheng Committed by NeilBrown Apr 08, 2015

md: fix md io stats accounting broken

Simon reported the md io stats accounting issue:
"
I'm seeing "iostat -x -k 1" print this after a RAID1 rebuild on 4.0-rc5.
It's not abnormal other than it's 3-disk, with one being SSD (sdc) and
the other two being write-mostly:

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdc 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
md0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 345.00 0.00 0.00 0.00 0.00 100.00
md2 0.00 0.00 0.00 0.00 0.00 0.00 0.00 58779.00 0.00 0.00 0.00 0.00 100.00
md1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 12.00 0.00 0.00 0.00 0.00 100.00
"
The cause is commit "18c0b223" uses the
generic_start_io_acct to account the disk stats rather than the open code,
but it also introduced the increase to .in_flight[rw] which is needless to
md. So we re-use the open code here to fix it.

Reported-by: Simon Kirby <sim@hostway.ca>
Cc: <stable@vger.kernel.org> 3.19
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: NeilBrown <neilb@suse.de>

parent f22e6e84

drivers/md/md.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -249,6 +249,7 @@ static void md_make_request(struct request_queue q, struct bio bio)
		const int rw = bio_data_dir(bio);
		struct mddev *mddev = q->queuedata;
		unsigned int sectors;
		int cpu;

		if (mddev == NULL \|\| mddev->pers == NULL
		\|\| !mddev->ready) {
		@@ -284,7 +285,10 @@ static void md_make_request(struct request_queue q, struct bio bio)
		sectors = bio_sectors(bio);
		mddev->pers->make_request(mddev, bio);

		generic_start_io_acct(rw, sectors, &mddev->gendisk->part0);
		cpu = part_stat_lock();
		part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
		part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], sectors);
		part_stat_unlock();

		if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
		wake_up(&mddev->sb_wait);

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