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blk-mq: use ->bi_bdev for I/O accounting 

Remove the reverse map from a sector to a partition for I/O accounting by
simply using ->bi_bdev.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2021-01-24 11:02:38 +01:00 committed by Jens Axboe
parent 99dfc43ecb
commit 0b6e522cdc
3 changed files with 5 additions and 51 deletions
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6
block/blk-core.c
View File

@ -1298,7 +1298,11 @@ void blk_account_io_start(struct request *rq)
if (!blk_do_io_stat(rq))
return;
rq->part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
/* passthrough requests can hold bios that do not have ->bi_bdev set */
if (rq->bio && rq->bio->bi_bdev)
rq->part = rq->bio->bi_bdev;
else
rq->part = rq->rq_disk->part0;
part_stat_lock();
update_io_ticks(rq->part, jiffies, false);

2
block/blk.h
View File

@ -333,8 +333,6 @@ void blk_queue_free_zone_bitmaps(struct request_queue *q);
static inline void blk_queue_free_zone_bitmaps(struct request_queue *q) {}
#endif
struct block_device *disk_map_sector_rcu(struct gendisk *disk, sector_t sector);
int blk_alloc_devt(struct block_device *part, dev_t *devt);
void blk_free_devt(dev_t devt);
char *disk_name(struct gendisk *hd, int partno, char *buf);

48
block/genhd.c
View File

@ -285,54 +285,6 @@ void disk_part_iter_exit(struct disk_part_iter *piter)
}
EXPORT_SYMBOL_GPL(disk_part_iter_exit);
static inline int sector_in_part(struct block_device *part, sector_t sector)
{
return part->bd_start_sect <= sector &&
sector < part->bd_start_sect + bdev_nr_sectors(part);
}
/**
* disk_map_sector_rcu - map sector to partition
* @disk: gendisk of interest
* @sector: sector to map
*
* Find out which partition @sector maps to on @disk. This is
* primarily used for stats accounting.
*
* CONTEXT:
* RCU read locked.
*
* RETURNS:
* Found partition on success, part0 is returned if no partition matches
* or the matched partition is being deleted.
*/
struct block_device *disk_map_sector_rcu(struct gendisk *disk, sector_t sector)
{
struct disk_part_tbl *ptbl;
struct block_device *part;
int i;
rcu_read_lock();
ptbl = rcu_dereference(disk->part_tbl);
part = rcu_dereference(ptbl->last_lookup);
if (part && sector_in_part(part, sector))
goto out_unlock;
for (i = 1; i < ptbl->len; i++) {
part = rcu_dereference(ptbl->part[i]);
if (part && sector_in_part(part, sector)) {
rcu_assign_pointer(ptbl->last_lookup, part);
goto out_unlock;
}
}
part = disk->part0;
out_unlock:
rcu_read_unlock();
return part;
}
/**
* disk_has_partitions
* @disk: gendisk of interest