blkcg: remove bio->bi_css and instead use bio->bi_blkg

Prior patches ensured that all bios are now associated with some blkg.
This now makes bio->bi_css unnecessary as blkg maintains a reference to
the blkcg already.

This patch removes the field bi_css and transfers corresponding uses to
access via bi_blkg.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 4 insertions, 3 deletions

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index ea9debf59b22..abad6d15f956 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -77,6 +77,7 @@
 #include <linux/falloc.h>
 #include <linux/uio.h>
 #include <linux/ioprio.h>
+#include <linux/blk-cgroup.h>
 
 #include "loop.h"
 
@@ -1760,8 +1761,8 @@ static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
 
         /* always use the first bio's css */
 #ifdef CONFIG_BLK_CGROUP
-        if (cmd->use_aio && rq->bio && rq->bio->bi_css) {
-                cmd->css = rq->bio->bi_css;
+        if (cmd->use_aio && rq->bio && rq->bio->bi_blkg) {
+                cmd->css = &bio_blkcg(rq->bio)->css;
                 css_get(cmd->css);
         } else
 #endif
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index ac1cffd2a09b..f3fb5bb8c82a 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -542,7 +542,7 @@ static void raid0_handle_discard(struct mddev *mddev, struct bio *bio)
                     !discard_bio)
                         continue;
                 bio_chain(discard_bio, bio);
-                bio_clone_blkcg_association(discard_bio, bio);
+                bio_clone_blkg_association(discard_bio, bio);
                 if (mddev->gendisk)
                         trace_block_bio_remap(bdev_get_queue(rdev->bdev),
                                 discard_bio, disk_devt(mddev->gendisk),