From: Jens Axboe <axboe@fb.com>
Date: Fri, 9 Dec 2016 23:16:30 +0000 (-0700)
Subject: blk-stat: fix a few cases of missing batch flushing
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=refs%2Fheads%2Fwb-buf-throttle-v4.7;p=linux-2.6-block.git

blk-stat: fix a few cases of missing batch flushing

Everytime we need to read ->nr_samples, we should have flushed
the batch first. The non-mq read path also needs to flush the
batch.

Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/block/blk-stat.c b/block/blk-stat.c
index bdb16d84b914..f6ede163fe12 100644
--- a/block/blk-stat.c
+++ b/block/blk-stat.c
@@ -61,6 +61,9 @@ static void blk_mq_stat_get(struct request_queue *q, struct blk_rq_stat *dst)
 
 		queue_for_each_hw_ctx(q, hctx, i) {
 			hctx_for_each_ctx(hctx, ctx, j) {
+				blk_stat_flush_batch(&ctx->stat[0]);
+				blk_stat_flush_batch(&ctx->stat[1]);
+
 				if (!ctx->stat[0].nr_samples &&
 				    !ctx->stat[1].nr_samples)
 					continue;
@@ -106,6 +109,8 @@ void blk_queue_stat_get(struct request_queue *q, struct blk_rq_stat *dst)
 	if (q->mq_ops)
 		blk_mq_stat_get(q, dst);
 	else {
+		blk_stat_flush_batch(&q->rq_stats[0]);
+		blk_stat_flush_batch(&q->rq_stats[1]);
 		memcpy(&dst[0], &q->rq_stats[0], sizeof(struct blk_rq_stat));
 		memcpy(&dst[1], &q->rq_stats[1], sizeof(struct blk_rq_stat));
 	}
@@ -121,6 +126,9 @@ void blk_hctx_stat_get(struct blk_mq_hw_ctx *hctx, struct blk_rq_stat *dst)
 		uint64_t newest = 0;
 
 		hctx_for_each_ctx(hctx, ctx, i) {
+			blk_stat_flush_batch(&ctx->stat[0]);
+			blk_stat_flush_batch(&ctx->stat[1]);
+
 			if (!ctx->stat[0].nr_samples &&
 			    !ctx->stat[1].nr_samples)
 				continue;