block: avoid duplicate calls to get_part() in disk stat code

get_part() is fairly expensive, as it O(N) loops over partitions
to find the right one. In lots of normal IO paths we end up looking
up the partition twice, to make matters even worse. Change the
stat add code to accept a passed in partition instead.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/block/aoe/aoecmd.c b/drivers/block/aoe/aoecmd.c
index 8fc429c..41f818b 100644
--- a/drivers/block/aoe/aoecmd.c
+++ b/drivers/block/aoe/aoecmd.c
@@ -755,11 +755,13 @@ diskstats(struct gendisk *disk, struct bio *bio, ulong duration, sector_t sector
 {
 	unsigned long n_sect = bio->bi_size >> 9;
 	const int rw = bio_data_dir(bio);
+	struct hd_struct *part;
 
-	all_stat_inc(disk, ios[rw], sector);
-	all_stat_add(disk, ticks[rw], duration, sector);
-	all_stat_add(disk, sectors[rw], n_sect, sector);
-	all_stat_add(disk, io_ticks, duration, sector);
+	part = get_part(disk, sector);
+	all_stat_inc(disk, part, ios[rw], sector);
+	all_stat_add(disk, part, ticks[rw], duration, sector);
+	all_stat_add(disk, part, sectors[rw], n_sect, sector);
+	all_stat_add(disk, part, io_ticks, duration, sector);
 }
 
 void