block: move stats from disk to part0

Move stats related fields - stamp, in_flight, dkstats - from disk to
part0 and unify stat handling such that...

* part_stat_*() now updates part0 together if the specified partition
  is not part0.  ie. part_stat_*() are now essentially all_stat_*().

* {disk|all}_stat_*() are gone.

* part_round_stats() is updated similary.  It handles part0 stats
  automatically and disk_round_stats() is killed.

* part_{inc|dec}_in_fligh() is implemented which automatically updates
  part0 stats for parts other than part0.

* disk_map_sector_rcu() is updated to return part0 if no part matches.
  Combined with the above changes, this makes NULL special case
  handling in callers unnecessary.

* Separate stats show code paths for disk are collapsed into part
  stats show code paths.

* Rename disk_stat_lock/unlock() to part_stat_lock/unlock()

While at it, reposition stat handling macros a bit and add missing
parentheses around macro parameters.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 5899f211515f..ae16794bef20 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3396,10 +3396,11 @@ static int make_request(struct request_queue *q, struct bio * bi)
 
         md_write_start(mddev, bi);
 
-        cpu = disk_stat_lock();
-        disk_stat_inc(cpu, mddev->gendisk, ios[rw]);
-        disk_stat_add(cpu, mddev->gendisk, sectors[rw], bio_sectors(bi));
-        disk_stat_unlock();
+        cpu = part_stat_lock();
+        part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
+        part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
+                      bio_sectors(bi));
+        part_stat_unlock();
 
         if (rw == READ &&
              mddev->reshape_position == MaxSector &&