[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>
diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index 9c06c54..8dc1822 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -246,8 +246,8 @@
 static ssize_t part_stat_read(struct hd_struct * p, char *page)
 {
 	return sprintf(page, "%8u %8llu %8u %8llu\n",
-		       p->reads, (unsigned long long)p->read_sectors,
-		       p->writes, (unsigned long long)p->write_sectors);
+		       p->ios[0], (unsigned long long)p->sectors[0],
+		       p->ios[1], (unsigned long long)p->sectors[1]);
 }
 static struct part_attribute part_attr_uevent = {
 	.attr = {.name = "uevent", .mode = S_IWUSR },
@@ -303,7 +303,8 @@
 	disk->part[part-1] = NULL;
 	p->start_sect = 0;
 	p->nr_sects = 0;
-	p->reads = p->writes = p->read_sectors = p->write_sectors = 0;
+	p->ios[0] = p->ios[1] = 0;
+	p->sectors[0] = p->sectors[1] = 0;
 	devfs_remove("%s/part%d", disk->devfs_name, part);
 	kobject_unregister(&p->kobj);
 }