[PATCH 07/10] blk-mq: use ->bi_bdev for I/O accounting

Christoph Hellwig
2021-01-24T10:06:50Z

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>
---
block/blk-core.c | 6 +++++-
block/blk.h | 2 --
block/genhd.c | 48 ------------------------------------------------
3 files changed, 5 insertions(+), 51 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 9315311c27a913..6dfbdde6b9ff84 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -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);
diff --git a/block/blk.h b/block/blk.h
index 10ab7c0d0766f0..d965cacc5bdaa1 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -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);
diff --git a/block/genhd.c b/block/genhd.c
index e536d0b4bbae34..e46de616a19e59 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -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
--
2.29.2