[dm-devel] [PATCH v2 10/14] block: add bio_start_io_acct_remapped for the benefit of DM

[Mike Snitzer]

DM needs the ability to account a clone bio's IO to the original
block_device. So add @orig_bdev argument to bio_start_io_acct_time.

Rename bio_start_io_acct_time to bio_start_io_acct_remapped.

Also, follow bio_end_io_acct and bio_end_io_acct_remapped pattern by
moving bio_start_io_acct to blkdev.h and have it call
bio_start_io_acct_remapped.

Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
 block/blk-core.c       | 24 ++++++++----------------
 drivers/md/dm.c        |  3 ++-
 include/linux/blkdev.h | 16 ++++++++++++++--
 3 files changed, 24 insertions(+), 19 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index be8812f5489d..8f23be96c737 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1077,29 +1077,21 @@ static unsigned long __part_start_io_acct(struct block_device *part,
 }
 
 /**
- * bio_start_io_acct_time - start I/O accounting for bio based drivers
+ * bio_start_io_acct_remapped - start I/O accounting for bio based drivers
  * @bio:	bio to start account for
  * @start_time:	start time that should be passed back to bio_end_io_acct().
- */
-void bio_start_io_acct_time(struct bio *bio, unsigned long start_time)
-{
-	__part_start_io_acct(bio->bi_bdev, bio_sectors(bio),
-			     bio_op(bio), start_time);
-}
-EXPORT_SYMBOL_GPL(bio_start_io_acct_time);
-
-/**
- * bio_start_io_acct - start I/O accounting for bio based drivers
- * @bio:	bio to start account for
+ * @orig_bdev:	block device that I/O must be accounted to.
  *
  * Returns the start time that should be passed back to bio_end_io_acct().
  */
-unsigned long bio_start_io_acct(struct bio *bio)
+unsigned long bio_start_io_acct_remapped(struct bio *bio,
+				unsigned long start_time,
+				struct block_device *orig_bdev)
 {
-	return __part_start_io_acct(bio->bi_bdev, bio_sectors(bio),
-				    bio_op(bio), jiffies);
+	return __part_start_io_acct(orig_bdev, bio_sectors(bio),
+				    bio_op(bio), start_time);
 }
-EXPORT_SYMBOL_GPL(bio_start_io_acct);
+EXPORT_SYMBOL_GPL(bio_start_io_acct_remapped);
 
 unsigned long disk_start_io_acct(struct gendisk *disk, unsigned int sectors,
 				 unsigned int op)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 72686329f91e..c0177552b471 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -489,7 +489,8 @@ static void start_io_acct(struct dm_io *io)
 {
 	struct bio *bio = io->orig_bio;
 
-	bio_start_io_acct_time(bio, io->start_time);
+	bio_start_io_acct_remapped(bio, io->start_time,
+				   io->orig_bio->bi_bdev);
 
 	if (unlikely(dm_stats_used(&io->md->stats)))
 		dm_stats_account_io(&io->md->stats, bio_data_dir(bio),
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 3bfc75a2a450..31d055d4a17e 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1512,11 +1512,23 @@ unsigned long disk_start_io_acct(struct gendisk *disk, unsigned int sectors,
 void disk_end_io_acct(struct gendisk *disk, unsigned int op,
 		unsigned long start_time);
 
-void bio_start_io_acct_time(struct bio *bio, unsigned long start_time);
-unsigned long bio_start_io_acct(struct bio *bio);
+unsigned long bio_start_io_acct_remapped(struct bio *bio,
+				unsigned long start_time,
+				struct block_device *orig_bdev);
 void bio_end_io_acct_remapped(struct bio *bio, unsigned long start_time,
 		struct block_device *orig_bdev);
 
+/**
+ * bio_start_io_acct - start I/O accounting for bio based drivers
+ * @bio:	bio to start account for
+ *
+ * Returns the start time that should be passed back to bio_end_io_acct().
+ */
+static inline unsigned long bio_start_io_acct(struct bio *bio)
+{
+	return bio_start_io_acct_remapped(bio, jiffies, bio->bi_bdev);
+}
+
 /**
  * bio_end_io_acct - end I/O accounting for bio based drivers
  * @bio:	bio to end account for
-- 
2.15.0