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, 14 insertions, 13 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 637806695bb9..327de03a5bdf 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -381,10 +381,10 @@ static void start_io_acct(struct dm_io *io)
 
         io->start_time = jiffies;
 
-        cpu = disk_stat_lock();
-        disk_round_stats(cpu, dm_disk(md));
-        disk_stat_unlock();
-        dm_disk(md)->in_flight = atomic_inc_return(&md->pending);
+        cpu = part_stat_lock();
+        part_round_stats(cpu, &dm_disk(md)->part0);
+        part_stat_unlock();
+        dm_disk(md)->part0.in_flight = atomic_inc_return(&md->pending);
 }
 
 static int end_io_acct(struct dm_io *io)
@@ -395,12 +395,13 @@ static int end_io_acct(struct dm_io *io)
         int pending, cpu;
         int rw = bio_data_dir(bio);
 
-        cpu = disk_stat_lock();
-        disk_round_stats(cpu, dm_disk(md));
-        disk_stat_add(cpu, dm_disk(md), ticks[rw], duration);
-        disk_stat_unlock();
+        cpu = part_stat_lock();
+        part_round_stats(cpu, &dm_disk(md)->part0);
+        part_stat_add(cpu, &dm_disk(md)->part0, ticks[rw], duration);
+        part_stat_unlock();
 
-        dm_disk(md)->in_flight = pending = atomic_dec_return(&md->pending);
+        dm_disk(md)->part0.in_flight = pending =
+                atomic_dec_return(&md->pending);
 
         return !pending;
 }
@@ -899,10 +900,10 @@ static int dm_request(struct request_queue *q, struct bio *bio)
 
         down_read(&md->io_lock);
 
-        cpu = disk_stat_lock();
-        disk_stat_inc(cpu, dm_disk(md), ios[rw]);
-        disk_stat_add(cpu, dm_disk(md), sectors[rw], bio_sectors(bio));
-        disk_stat_unlock();
+        cpu = part_stat_lock();
+        part_stat_inc(cpu, &dm_disk(md)->part0, ios[rw]);
+        part_stat_add(cpu, &dm_disk(md)->part0, sectors[rw], bio_sectors(bio));
+        part_stat_unlock();
 
         /*
          * If we're suspended we have to queue