bcache: use part_[begin|end]_io_acct instead of disk_[begin|end]_io_acct

This enables proper statistics in /proc/diskstats for bcache partitions.
Signed-off-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Coly Li <colyli@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/md/bcache/request.c

@@ -475,6 +475,7 @@ struct search {
 	unsigned int		read_dirty_data:1;
 	unsigned int		cache_missed:1;
 
+	struct hd_struct	*part;
 	unsigned long		start_time;
 
 	struct btree_op		op;
@@ -669,7 +670,7 @@ static void bio_complete(struct search *s)
 {
 	if (s->orig_bio) {
 		/* Count on bcache device */
-		disk_end_io_acct(s->d->disk, bio_op(s->orig_bio), s->start_time);
+		part_end_io_acct(s->part, s->orig_bio, s->start_time);
 
 		trace_bcache_request_end(s->d, s->orig_bio);
 		s->orig_bio->bi_status = s->iop.status;
@@ -731,7 +732,7 @@ static inline struct search *search_alloc(struct bio *bio,
 	s->write		= op_is_write(bio_op(bio));
 	s->read_dirty_data	= 0;
 	/* Count on the bcache device */
-	s->start_time		= disk_start_io_acct(d->disk, bio_sectors(bio), bio_op(bio));
+	s->start_time		= part_start_io_acct(d->disk, &s->part, bio);
 	s->iop.c		= d->c;
 	s->iop.bio		= NULL;
 	s->iop.inode		= d->id;
@@ -1072,6 +1073,7 @@ struct detached_dev_io_private {
 	unsigned long		start_time;
 	bio_end_io_t		*bi_end_io;
 	void			*bi_private;
+	struct hd_struct	*part;
 };
 
 static void detached_dev_end_io(struct bio *bio)
@@ -1083,7 +1085,7 @@ static void detached_dev_end_io(struct bio *bio)
 	bio->bi_private = ddip->bi_private;
 
 	/* Count on the bcache device */
-	disk_end_io_acct(ddip->d->disk, bio_op(bio), ddip->start_time);
+	part_end_io_acct(ddip->part, bio, ddip->start_time);
 
 	if (bio->bi_status) {
 		struct cached_dev *dc = container_of(ddip->d,
@@ -1109,7 +1111,7 @@ static void detached_dev_do_request(struct bcache_device *d, struct bio *bio)
 	ddip = kzalloc(sizeof(struct detached_dev_io_private), GFP_NOIO);
 	ddip->d = d;
 	/* Count on the bcache device */
-	ddip->start_time = disk_start_io_acct(d->disk, bio_sectors(bio), bio_op(bio));
+	ddip->start_time = part_start_io_acct(d->disk, &ddip->part, bio);
 	ddip->bi_end_io = bio->bi_end_io;
 	ddip->bi_private = bio->bi_private;
 	bio->bi_end_io = detached_dev_end_io;