[BLOCK] Unify the seperate read/write io stat fields into arrays

Instead of having ->read_sectors and ->write_sectors, combine the two
into ->sectors[2] and similar for the other fields. This saves a branch
several places in the io path, since we don't have to care for what the
actual io direction is. On my x86-64 box, that's 200 bytes less text in
just the core (not counting the various drivers).

Signed-off-by: Jens Axboe <axboe@suse.de>

2 files changed, 26 insertions, 43 deletions

diff --git a/drivers/block/genhd.c b/drivers/block/genhd.c
index 486ce1fdeb8..54aec4a1ae1 100644
--- a/drivers/block/genhd.c
+++ b/drivers/block/genhd.c
@@ -391,13 +391,12 @@ static ssize_t disk_stats_read(struct gendisk * disk, char *page)
 		"%8u %8u %8llu %8u "
 		"%8u %8u %8u"
 		"\n",
-		disk_stat_read(disk, reads), disk_stat_read(disk, read_merges),
-		(unsigned long long)disk_stat_read(disk, read_sectors),
-		jiffies_to_msecs(disk_stat_read(disk, read_ticks)),
-		disk_stat_read(disk, writes), 
-		disk_stat_read(disk, write_merges),
-		(unsigned long long)disk_stat_read(disk, write_sectors),
-		jiffies_to_msecs(disk_stat_read(disk, write_ticks)),
+		disk_stat_read(disk, ios[0]), disk_stat_read(disk, merges[0]),
+		(unsigned long long)disk_stat_read(disk, sectors[0]),
+		jiffies_to_msecs(disk_stat_read(disk, ticks[0])),
+		disk_stat_read(disk, ios[1]), disk_stat_read(disk, merges[1]),
+		(unsigned long long)disk_stat_read(disk, sectors[1]),
+		jiffies_to_msecs(disk_stat_read(disk, ticks[1])),
 		disk->in_flight,
 		jiffies_to_msecs(disk_stat_read(disk, io_ticks)),
 		jiffies_to_msecs(disk_stat_read(disk, time_in_queue)));
@@ -583,12 +582,12 @@ static int diskstats_show(struct seq_file *s, void *v)
 	preempt_enable();
 	seq_printf(s, "%4d %4d %s %u %u %llu %u %u %u %llu %u %u %u %u\n",
 		gp->major, n + gp->first_minor, disk_name(gp, n, buf),
-		disk_stat_read(gp, reads), disk_stat_read(gp, read_merges),
-		(unsigned long long)disk_stat_read(gp, read_sectors),
-		jiffies_to_msecs(disk_stat_read(gp, read_ticks)),
-		disk_stat_read(gp, writes), disk_stat_read(gp, write_merges),
-		(unsigned long long)disk_stat_read(gp, write_sectors),
-		jiffies_to_msecs(disk_stat_read(gp, write_ticks)),
+		disk_stat_read(gp, ios[0]), disk_stat_read(gp, merges[0]),
+		(unsigned long long)disk_stat_read(gp, sectors[0]),
+		jiffies_to_msecs(disk_stat_read(gp, ticks[0])),
+		disk_stat_read(gp, ios[1]), disk_stat_read(gp, merges[1]),
+		(unsigned long long)disk_stat_read(gp, sectors[1]),
+		jiffies_to_msecs(disk_stat_read(gp, ticks[1])),
 		gp->in_flight,
 		jiffies_to_msecs(disk_stat_read(gp, io_ticks)),
 		jiffies_to_msecs(disk_stat_read(gp, time_in_queue)));
@@ -601,8 +600,8 @@ static int diskstats_show(struct seq_file *s, void *v)
 			seq_printf(s, "%4d %4d %s %u %u %u %u\n",
 				gp->major, n + gp->first_minor + 1,
 				disk_name(gp, n + 1, buf),
-				hd->reads, hd->read_sectors,
-				hd->writes, hd->write_sectors);
+				hd->ios[0], hd->sectors[0],
+				hd->ios[1], hd->sectors[1]);
 	}
  
 	return 0;
diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
index 1b272883aad..2747741677f 100644
--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -2388,10 +2388,7 @@ static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io)
 		return;
 
 	if (!new_io) {
-		if (rw == READ)
-			__disk_stat_inc(rq->rq_disk, read_merges);
-		else
-			__disk_stat_inc(rq->rq_disk, write_merges);
+		__disk_stat_inc(rq->rq_disk, merges[rw]);
 	} else {
 		disk_round_stats(rq->rq_disk);
 		rq->rq_disk->in_flight++;
@@ -2787,17 +2784,11 @@ static inline void blk_partition_remap(struct bio *bio)
 
 	if (bdev != bdev->bd_contains) {
 		struct hd_struct *p = bdev->bd_part;
+		const int rw = bio_data_dir(bio);
+
+		p->sectors[rw] += bio_sectors(bio);
+		p->ios[rw]++;
 
-		switch (bio_data_dir(bio)) {
-		case READ:
-			p->read_sectors += bio_sectors(bio);
-			p->reads++;
-			break;
-		case WRITE:
-			p->write_sectors += bio_sectors(bio);
-			p->writes++;
-			break;
-		}
 		bio->bi_sector += p->start_sect;
 		bio->bi_bdev = bdev->bd_contains;
 	}
@@ -3045,10 +3036,9 @@ static int __end_that_request_first(struct request *req, int uptodate,
 	}
 
 	if (blk_fs_request(req) && req->rq_disk) {
-		if (rq_data_dir(req) == READ)
-			__disk_stat_add(req->rq_disk, read_sectors, nr_bytes >> 9);
-		else
-			__disk_stat_add(req->rq_disk, write_sectors, nr_bytes >> 9);
+		const int rw = rq_data_dir(req);
+
+		__disk_stat_add(req->rq_disk, sectors[rw], nr_bytes >> 9);
 	}
 
 	total_bytes = bio_nbytes = 0;
@@ -3179,16 +3169,10 @@ void end_that_request_last(struct request *req)
 
 	if (disk && blk_fs_request(req)) {
 		unsigned long duration = jiffies - req->start_time;
-		switch (rq_data_dir(req)) {
-		    case WRITE:
-			__disk_stat_inc(disk, writes);
-			__disk_stat_add(disk, write_ticks, duration);
-			break;
-		    case READ:
-			__disk_stat_inc(disk, reads);
-			__disk_stat_add(disk, read_ticks, duration);
-			break;
-		}
+		const int rw = rq_data_dir(req);
+
+		__disk_stat_inc(disk, ios[rw]);
+		__disk_stat_add(disk, ticks[rw], duration);
 		disk_round_stats(disk);
 		disk->in_flight--;
 	}