libnvdimm: use generic iostat interfaces

nd_iostat_start() and nd_iostat_end() implement the same functionality
that generic_start_io_acct() and generic_end_io_acct() already provide.

Change nd_iostat_start() and nd_iostat_end() to call the generic iostat
interfaces.  There is no change in the nd interfaces.
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/nvdimm/core.c

@@ -317,35 +317,6 @@ ssize_t nd_sector_size_store(struct device *dev, const char *buf,
 	}
 }
 
-void __nd_iostat_start(struct bio *bio, unsigned long *start)
-{
-	struct gendisk *disk = bio->bi_bdev->bd_disk;
-	const int rw = bio_data_dir(bio);
-	int cpu = part_stat_lock();
-
-	*start = jiffies;
-	part_round_stats(cpu, &disk->part0);
-	part_stat_inc(cpu, &disk->part0, ios[rw]);
-	part_stat_add(cpu, &disk->part0, sectors[rw], bio_sectors(bio));
-	part_inc_in_flight(&disk->part0, rw);
-	part_stat_unlock();
-}
-EXPORT_SYMBOL(__nd_iostat_start);
-
-void nd_iostat_end(struct bio *bio, unsigned long start)
-{
-	struct gendisk *disk = bio->bi_bdev->bd_disk;
-	unsigned long duration = jiffies - start;
-	const int rw = bio_data_dir(bio);
-	int cpu = part_stat_lock();
-
-	part_stat_add(cpu, &disk->part0, ticks[rw], duration);
-	part_round_stats(cpu, &disk->part0);
-	part_dec_in_flight(&disk->part0, rw);
-	part_stat_unlock();
-}
-EXPORT_SYMBOL(nd_iostat_end);
-
 static ssize_t commands_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {

drivers/nvdimm/nd.h

@@ -377,10 +377,17 @@ static inline bool nd_iostat_start(struct bio *bio, unsigned long *start)
 	if (!blk_queue_io_stat(disk->queue))
 		return false;
 
-	__nd_iostat_start(bio, start);
+	*start = jiffies;
+	generic_start_io_acct(bio_data_dir(bio),
+			      bio_sectors(bio), &disk->part0);
 	return true;
 }
-void nd_iostat_end(struct bio *bio, unsigned long start);
+static inline void nd_iostat_end(struct bio *bio, unsigned long start)
+{
+	struct gendisk *disk = bio->bi_bdev->bd_disk;
+
+	generic_end_io_acct(bio_data_dir(bio), &disk->part0, start);
+}
 static inline bool is_bad_pmem(struct badblocks *bb, sector_t sector,
 		unsigned int len)
 {