Commit f2987c58 authored by Yu Kuai's avatar Yu Kuai
Browse files

block: export API to get the number of bdev inflight IO 

- rename part_in_{flight, flight_rw} to bdev_count_{inflight, inflight_rw}
- export bdev_count_inflight, to fix a problem in mdraid that foreground
  IO can be starved by background sync IO in later patches

Link: https://lore.kernel.org/linux-raid/20250506124903.2540268-6-yukuai1@huaweicloud.com


Signed-off-by: default avatarYu Kuai <yukuai3@huawei.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
parent 6b6c3a97

block/blk-core.c

+1 −1
Original line number Diff line number Diff line
@@ -1018,7 +1018,7 @@ void update_io_ticks(struct block_device *part, unsigned long now, bool end) 
	stamp = READ_ONCE(part->bd_stamp);

	if (unlikely(time_after(now, stamp)) &&

	    likely(try_cmpxchg(&part->bd_stamp, &stamp, now)) &&

	    (end || part_in_flight(part)))

	    (end || bdev_count_inflight(part)))

		__part_stat_add(part, io_ticks, now - stamp);



	if (bdev_is_partition(part)) {

block/blk.h

+0 −1
Original line number Diff line number Diff line
@@ -419,7 +419,6 @@ void blk_apply_bdi_limits(struct backing_dev_info *bdi, 
int blk_dev_init(void);



void update_io_ticks(struct block_device *part, unsigned long now, bool end);

unsigned int part_in_flight(struct block_device *part);



static inline void req_set_nomerge(struct request_queue *q, struct request *req)

{

block/genhd.c

+16 −6
Original line number Diff line number Diff line
@@ -125,7 +125,7 @@ static void part_stat_read_all(struct block_device *part, 
	}

}



static void part_in_flight_rw(struct block_device *part,

static void bdev_count_inflight_rw(struct block_device *part,

		unsigned int inflight[2], bool mq_driver)

{

	int cpu;
@@ -147,14 +147,24 @@ static void part_in_flight_rw(struct block_device *part, 
		inflight[WRITE] = 0;

}



unsigned int part_in_flight(struct block_device *part)

/**

 * bdev_count_inflight - get the number of inflight IOs for a block device.

 *

 * @part: the block device.

 *

 * Inflight here means started IO accounting, from bdev_start_io_acct() for

 * bio-based block device, and from blk_account_io_start() for rq-based block

 * device.

 */

unsigned int bdev_count_inflight(struct block_device *part)

{

	unsigned int inflight[2] = {0};



	part_in_flight_rw(part, inflight, false);

	bdev_count_inflight_rw(part, inflight, false);



	return inflight[READ] + inflight[WRITE];

}

EXPORT_SYMBOL_GPL(bdev_count_inflight);



/*

 * Can be deleted altogether. Later.
@@ -1052,7 +1062,7 @@ ssize_t part_stat_show(struct device *dev, 
	struct disk_stats stat;

	unsigned int inflight;



	inflight = part_in_flight(bdev);

	inflight = bdev_count_inflight(bdev);

	if (inflight) {

		part_stat_lock();

		update_io_ticks(bdev, jiffies, true);
@@ -1101,7 +1111,7 @@ ssize_t part_inflight_show(struct device *dev, struct device_attribute *attr, 
	struct request_queue *q = bdev_get_queue(bdev);

	unsigned int inflight[2] = {0};



	part_in_flight_rw(bdev, inflight, queue_is_mq(q));

	bdev_count_inflight_rw(bdev, inflight, queue_is_mq(q));



	return sysfs_emit(buf, "%8u %8u\n", inflight[READ], inflight[WRITE]);

}
@@ -1356,7 +1366,7 @@ static int diskstats_show(struct seq_file *seqf, void *v) 
		if (bdev_is_partition(hd) && !bdev_nr_sectors(hd))

			continue;



		inflight = part_in_flight(hd);

		inflight = bdev_count_inflight(hd);

		if (inflight) {

			part_stat_lock();

			update_io_ticks(hd, jiffies, true);

include/linux/part_stat.h

+2 −0
Original line number Diff line number Diff line
@@ -79,4 +79,6 @@ static inline void part_stat_set_all(struct block_device *part, int value) 
#define part_stat_local_read_cpu(part, field, cpu)			\

	local_read(&(part_stat_get_cpu(part, field, cpu)))



unsigned int bdev_count_inflight(struct block_device *part);



#endif /* _LINUX_PART_STAT_H */