Commit 5f275713 authored by Yu Kuai's avatar Yu Kuai Committed by Jens Axboe
Browse files

block: count 'ios' and 'sectors' when io is done for bio-based device 



While using iostat for raid, I observed very strange 'await'
occasionally, and turns out it's due to that 'ios' and 'sectors' is
counted in bdev_start_io_acct(), while 'nsecs' is counted in
bdev_end_io_acct(). I'm not sure why they are ccounted like that
but I think this behaviour is obviously wrong because user will get
wrong disk stats.

Fix the problem by counting 'ios' and 'sectors' when io is done, like
what rq-based device does.

Fixes: 394ffa50 ("blk: introduce generic io stat accounting help function")
Signed-off-by: default avatarYu Kuai <yukuai3@huawei.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230223091226.1135678-1-yukuai1@huaweicloud.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 60303631

block/blk-core.c

+6 −10
Original line number Diff line number Diff line
@@ -959,16 +959,11 @@ void update_io_ticks(struct block_device *part, unsigned long now, bool end) 
	}

}



unsigned long bdev_start_io_acct(struct block_device *bdev,

				 unsigned int sectors, enum req_op op,

unsigned long bdev_start_io_acct(struct block_device *bdev, enum req_op op,

				 unsigned long start_time)

{

	const int sgrp = op_stat_group(op);



	part_stat_lock();

	update_io_ticks(bdev, start_time, false);

	part_stat_inc(bdev, ios[sgrp]);

	part_stat_add(bdev, sectors[sgrp], sectors);

	part_stat_local_inc(bdev, in_flight[op_is_write(op)]);

	part_stat_unlock();
@@ -984,13 +979,12 @@ EXPORT_SYMBOL(bdev_start_io_acct); 
 */

unsigned long bio_start_io_acct(struct bio *bio)

{

	return bdev_start_io_acct(bio->bi_bdev, bio_sectors(bio),

				  bio_op(bio), jiffies);

	return bdev_start_io_acct(bio->bi_bdev, bio_op(bio), jiffies);

}

EXPORT_SYMBOL_GPL(bio_start_io_acct);



void bdev_end_io_acct(struct block_device *bdev, enum req_op op,

		      unsigned long start_time)

		      unsigned int sectors, unsigned long start_time)

{

	const int sgrp = op_stat_group(op);

	unsigned long now = READ_ONCE(jiffies);
@@ -998,6 +992,8 @@ void bdev_end_io_acct(struct block_device *bdev, enum req_op op, 


	part_stat_lock();

	update_io_ticks(bdev, now, true);

	part_stat_inc(bdev, ios[sgrp]);

	part_stat_add(bdev, sectors[sgrp], sectors);

	part_stat_add(bdev, nsecs[sgrp], jiffies_to_nsecs(duration));

	part_stat_local_dec(bdev, in_flight[op_is_write(op)]);

	part_stat_unlock();
@@ -1007,7 +1003,7 @@ EXPORT_SYMBOL(bdev_end_io_acct); 
void bio_end_io_acct_remapped(struct bio *bio, unsigned long start_time,

			      struct block_device *orig_bdev)

{

	bdev_end_io_acct(orig_bdev, bio_op(bio), start_time);

	bdev_end_io_acct(orig_bdev, bio_op(bio), bio_sectors(bio), start_time);

}

EXPORT_SYMBOL_GPL(bio_end_io_acct_remapped);

drivers/md/dm.c

+3 −3
Original line number Diff line number Diff line
@@ -512,10 +512,10 @@ static void dm_io_acct(struct dm_io *io, bool end) 
		sectors = io->sectors;



	if (!end)

		bdev_start_io_acct(bio->bi_bdev, sectors, bio_op(bio),

				   start_time);

		bdev_start_io_acct(bio->bi_bdev, bio_op(bio), start_time);

	else

		bdev_end_io_acct(bio->bi_bdev, bio_op(bio), start_time);

		bdev_end_io_acct(bio->bi_bdev, bio_op(bio), sectors,

				 start_time);



	if (static_branch_unlikely(&stats_enabled) &&

	    unlikely(dm_stats_used(&md->stats))) {

drivers/nvme/host/multipath.c

+4 −4
Original line number Diff line number Diff line
@@ -123,9 +123,8 @@ void nvme_mpath_start_request(struct request *rq) 
		return;



	nvme_req(rq)->flags |= NVME_MPATH_IO_STATS;

	nvme_req(rq)->start_time = bdev_start_io_acct(disk->part0,

					blk_rq_bytes(rq) >> SECTOR_SHIFT,

					req_op(rq), jiffies);

	nvme_req(rq)->start_time = bdev_start_io_acct(disk->part0, req_op(rq),

						      jiffies);

}

EXPORT_SYMBOL_GPL(nvme_mpath_start_request);
@@ -136,6 +135,7 @@ void nvme_mpath_end_request(struct request *rq) 
	if (!(nvme_req(rq)->flags & NVME_MPATH_IO_STATS))

		return;

	bdev_end_io_acct(ns->head->disk->part0, req_op(rq),

			 blk_rq_bytes(rq) >> SECTOR_SHIFT,

			 nvme_req(rq)->start_time);

}

include/linux/blkdev.h

+2 −3
Original line number Diff line number Diff line
@@ -1446,11 +1446,10 @@ static inline void blk_wake_io_task(struct task_struct *waiter) 
		wake_up_process(waiter);

}



unsigned long bdev_start_io_acct(struct block_device *bdev,

				 unsigned int sectors, enum req_op op,

unsigned long bdev_start_io_acct(struct block_device *bdev, enum req_op op,

				 unsigned long start_time);

void bdev_end_io_acct(struct block_device *bdev, enum req_op op,

		unsigned long start_time);

		      unsigned int sectors, unsigned long start_time);



unsigned long bio_start_io_acct(struct bio *bio);

void bio_end_io_acct_remapped(struct bio *bio, unsigned long start_time,