block: pass struct request instead of struct blk_issue_stat to wbt

issue_stat is going to go away, so first make writeback throttling take
the containing request, update the internal wbt helpers accordingly, and
change rwb->sync_cookie to be the request pointer instead of the
issue_stat pointer. No functional change.

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

block/blk-core.c

@@ -1659,7 +1659,7 @@ void blk_requeue_request(struct request_queue *q, struct request *rq)
 	blk_delete_timer(rq);
 	blk_clear_rq_complete(rq);
 	trace_block_rq_requeue(q, rq);
-	wbt_requeue(q->rq_wb, &rq->issue_stat);
+	wbt_requeue(q->rq_wb, rq);
 
 	if (rq->rq_flags & RQF_QUEUED)
 		blk_queue_end_tag(q, rq);
@@ -1766,7 +1766,7 @@ void __blk_put_request(struct request_queue *q, struct request *req)
 	/* this is a bio leak */
 	WARN_ON(req->bio != NULL);
 
-	wbt_done(q->rq_wb, &req->issue_stat);
+	wbt_done(q->rq_wb, req);
 
 	/*
 	 * Request may not have originated from ll_rw_blk. if not,
@@ -2077,7 +2077,7 @@ get_rq:
 		goto out_unlock;
 	}
 
-	wbt_track(&req->issue_stat, wb_acct);
+	wbt_track(req, wb_acct);
 
 	/*
 	 * After dropping the lock and possibly sleeping here, our request
@@ -2993,7 +2993,7 @@ void blk_start_request(struct request *req)
 	if (test_bit(QUEUE_FLAG_STATS, &req->q->queue_flags)) {
 		blk_stat_set_issue(&req->issue_stat, blk_rq_sectors(req));
 		req->rq_flags |= RQF_STATS;
-		wbt_issue(req->q->rq_wb, &req->issue_stat);
+		wbt_issue(req->q->rq_wb, req);
 	}
 
 	BUG_ON(blk_rq_is_complete(req));
@@ -3212,7 +3212,7 @@ void blk_finish_request(struct request *req, blk_status_t error)
 	blk_account_io_done(req);
 
 	if (req->end_io) {
-		wbt_done(req->q->rq_wb, &req->issue_stat);
+		wbt_done(req->q->rq_wb, req);
 		req->end_io(req, error);
 	} else {
 		if (blk_bidi_rq(req))

block/blk-mq.c

@@ -488,7 +488,7 @@ void blk_mq_free_request(struct request *rq)
 	if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))
 		laptop_io_completion(q->backing_dev_info);
 
-	wbt_done(q->rq_wb, &rq->issue_stat);
+	wbt_done(q->rq_wb, rq);
 
 	if (blk_rq_rl(rq))
 		blk_put_rl(blk_rq_rl(rq));
@@ -508,7 +508,7 @@ inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
 	blk_account_io_done(rq);
 
 	if (rq->end_io) {
-		wbt_done(rq->q->rq_wb, &rq->issue_stat);
+		wbt_done(rq->q->rq_wb, rq);
 		rq->end_io(rq, error);
 	} else {
 		if (unlikely(blk_bidi_rq(rq)))
@@ -671,7 +671,7 @@ void blk_mq_start_request(struct request *rq)
 	if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
 		blk_stat_set_issue(&rq->issue_stat, blk_rq_sectors(rq));
 		rq->rq_flags |= RQF_STATS;
-		wbt_issue(q->rq_wb, &rq->issue_stat);
+		wbt_issue(q->rq_wb, rq);
 	}
 
 	WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE);
@@ -719,7 +719,7 @@ static void __blk_mq_requeue_request(struct request *rq)
 	blk_mq_put_driver_tag(rq);
 
 	trace_block_rq_requeue(q, rq);
-	wbt_requeue(q->rq_wb, &rq->issue_stat);
+	wbt_requeue(q->rq_wb, rq);
 
 	if (blk_mq_rq_state(rq) != MQ_RQ_IDLE) {
 		blk_mq_rq_update_state(rq, MQ_RQ_IDLE);
@@ -1882,7 +1882,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 		return BLK_QC_T_NONE;
 	}
 
-	wbt_track(&rq->issue_stat, wb_acct);
+	wbt_track(rq, wb_acct);
 
 	cookie = request_to_qc_t(data.hctx, rq);
 

block/blk-wbt.c

@@ -29,24 +29,24 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/wbt.h>
 
-static inline void wbt_clear_state(struct blk_issue_stat *stat)
+static inline void wbt_clear_state(struct request *rq)
 {
-	stat->stat &= ~BLK_STAT_RES_MASK;
+	rq->issue_stat.stat &= ~BLK_STAT_RES_MASK;
 }
 
-static inline enum wbt_flags wbt_stat_to_mask(struct blk_issue_stat *stat)
+static inline enum wbt_flags wbt_flags(struct request *rq)
 {
-	return (stat->stat & BLK_STAT_RES_MASK) >> BLK_STAT_RES_SHIFT;
+	return (rq->issue_stat.stat & BLK_STAT_RES_MASK) >> BLK_STAT_RES_SHIFT;
 }
 
-static inline bool wbt_is_tracked(struct blk_issue_stat *stat)
+static inline bool wbt_is_tracked(struct request *rq)
 {
-	return (stat->stat >> BLK_STAT_RES_SHIFT) & WBT_TRACKED;
+	return (rq->issue_stat.stat >> BLK_STAT_RES_SHIFT) & WBT_TRACKED;
 }
 
-static inline bool wbt_is_read(struct blk_issue_stat *stat)
+static inline bool wbt_is_read(struct request *rq)
 {
-	return (stat->stat >> BLK_STAT_RES_SHIFT) & WBT_READ;
+	return (rq->issue_stat.stat >> BLK_STAT_RES_SHIFT) & WBT_READ;
 }
 
 enum {
@@ -194,24 +194,24 @@ void __wbt_done(struct rq_wb *rwb, enum wbt_flags wb_acct)
  * Called on completion of a request. Note that it's also called when
  * a request is merged, when the request gets freed.
  */
-void wbt_done(struct rq_wb *rwb, struct blk_issue_stat *stat)
+void wbt_done(struct rq_wb *rwb, struct request *rq)
 {
 	if (!rwb)
 		return;
 
-	if (!wbt_is_tracked(stat)) {
+	if (!wbt_is_tracked(rq)) {
-		if (rwb->sync_cookie == stat) {
+		if (rwb->sync_cookie == rq) {
 			rwb->sync_issue = 0;
 			rwb->sync_cookie = NULL;
 		}
 
-		if (wbt_is_read(stat))
+		if (wbt_is_read(rq))
 			wb_timestamp(rwb, &rwb->last_comp);
 	} else {
-		WARN_ON_ONCE(stat == rwb->sync_cookie);
+		WARN_ON_ONCE(rq == rwb->sync_cookie);
-		__wbt_done(rwb, wbt_stat_to_mask(stat));
+		__wbt_done(rwb, wbt_flags(rq));
 	}
-	wbt_clear_state(stat);
+	wbt_clear_state(rq);
 }
 
 /*
@@ -643,30 +643,29 @@ enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio, spinlock_t *lock)
 	return ret | WBT_TRACKED;
 }
 
-void wbt_issue(struct rq_wb *rwb, struct blk_issue_stat *stat)
+void wbt_issue(struct rq_wb *rwb, struct request *rq)
 {
 	if (!rwb_enabled(rwb))
 		return;
 
 	/*
-	 * Track sync issue, in case it takes a long time to complete. Allows
+	 * Track sync issue, in case it takes a long time to complete. Allows us
-	 * us to react quicker, if a sync IO takes a long time to complete.
+	 * to react quicker, if a sync IO takes a long time to complete. Note
-	 * Note that this is just a hint. 'stat' can go away when the
+	 * that this is just a hint. The request can go away when it completes,
-	 * request completes, so it's important we never dereference it. We
+	 * so it's important we never dereference it. We only use the address to
-	 * only use the address to compare with, which is why we store the
+	 * compare with, which is why we store the sync_issue time locally.
-	 * sync_issue time locally.
 	 */
-	if (wbt_is_read(stat) && !rwb->sync_issue) {
+	if (wbt_is_read(rq) && !rwb->sync_issue) {
-		rwb->sync_cookie = stat;
+		rwb->sync_cookie = rq;
-		rwb->sync_issue = blk_stat_time(stat);
+		rwb->sync_issue = blk_stat_time(&rq->issue_stat);
 	}
 }
 
-void wbt_requeue(struct rq_wb *rwb, struct blk_issue_stat *stat)
+void wbt_requeue(struct rq_wb *rwb, struct request *rq)
 {
 	if (!rwb_enabled(rwb))
 		return;
-	if (stat == rwb->sync_cookie) {
+	if (rq == rwb->sync_cookie) {
 		rwb->sync_issue = 0;
 		rwb->sync_cookie = NULL;
 	}

block/blk-wbt.h

@@ -88,19 +88,19 @@ static inline unsigned int wbt_inflight(struct rq_wb *rwb)
 
 #ifdef CONFIG_BLK_WBT
 
-static inline void wbt_track(struct blk_issue_stat *stat, enum wbt_flags flags)
+static inline void wbt_track(struct request *rq, enum wbt_flags flags)
 {
-	stat->stat |= ((u64)flags) << BLK_STAT_RES_SHIFT;
+	rq->issue_stat.stat |= ((u64)flags) << BLK_STAT_RES_SHIFT;
 }
 
 void __wbt_done(struct rq_wb *, enum wbt_flags);
-void wbt_done(struct rq_wb *, struct blk_issue_stat *);
+void wbt_done(struct rq_wb *, struct request *);
 enum wbt_flags wbt_wait(struct rq_wb *, struct bio *, spinlock_t *);
 int wbt_init(struct request_queue *);
 void wbt_exit(struct request_queue *);
 void wbt_update_limits(struct rq_wb *);
-void wbt_requeue(struct rq_wb *, struct blk_issue_stat *);
+void wbt_requeue(struct rq_wb *, struct request *);
-void wbt_issue(struct rq_wb *, struct blk_issue_stat *);
+void wbt_issue(struct rq_wb *, struct request *);
 void wbt_disable_default(struct request_queue *);
 void wbt_enable_default(struct request_queue *);
 
@@ -111,13 +111,13 @@ u64 wbt_default_latency_nsec(struct request_queue *);
 
 #else
 
-static inline void wbt_track(struct blk_issue_stat *stat, enum wbt_flags flags)
+static inline void wbt_track(struct request *rq, enum wbt_flags flags)
 {
 }
 static inline void __wbt_done(struct rq_wb *rwb, enum wbt_flags flags)
 {
 }
-static inline void wbt_done(struct rq_wb *rwb, struct blk_issue_stat *stat)
+static inline void wbt_done(struct rq_wb *rwb, struct request *rq)
 {
 }
 static inline enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio,
@@ -135,10 +135,10 @@ static inline void wbt_exit(struct request_queue *q)
 static inline void wbt_update_limits(struct rq_wb *rwb)
 {
 }
-static inline void wbt_requeue(struct rq_wb *rwb, struct blk_issue_stat *stat)
+static inline void wbt_requeue(struct rq_wb *rwb, struct request *rq)
 {
 }
-static inline void wbt_issue(struct rq_wb *rwb, struct blk_issue_stat *stat)
+static inline void wbt_issue(struct rq_wb *rwb, struct request *rq)
 {
 }
 static inline void wbt_disable_default(struct request_queue *q)