block: get rid of struct blk_issue_stat

struct blk_issue_stat squashes three things into one u64:

- The time the driver started working on a request
- The original size of the request (for the io.low controller)
- Flags for writeback throttling

It turns out that on x86_64, we have a 4 byte hole in struct request
which we can fill with the non-timestamp fields from blk_issue_stat,
simplifying things quite a bit.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 2 insertions, 2 deletions

diff --git a/block/blk-wbt.h b/block/blk-wbt.h
index 85fbcccf12a5..300df531d0a6 100644
--- a/block/blk-wbt.h
+++ b/block/blk-wbt.h
@@ -63,7 +63,7 @@ struct rq_wb {
 
 	struct blk_stat_callback *cb;
 
-	s64 sync_issue;
+	u64 sync_issue;
 	void *sync_cookie;
 
 	unsigned int wc;
@@ -90,7 +90,7 @@ static inline unsigned int wbt_inflight(struct rq_wb *rwb)
 
 static inline void wbt_track(struct request *rq, enum wbt_flags flags)
 {
-	rq->issue_stat.stat |= ((u64)flags) << BLK_STAT_RES_SHIFT;
+	rq->wbt_flags |= flags;
 }
 
 void __wbt_done(struct rq_wb *, enum wbt_flags);