[RFC PATCH 3/6] blk-mq: factor out a per-hctx tag busy iterator

[Keith Busch <kbusch@meta.com>]

From: Keith Busch <kbusch@kernel.org>

Make a helper for walking the busy tags of specific hardware queue based
on the per-hctx walk into __blk_mq_hctx_tag_busy_iter() so it can be
reused to iterate a single hardware queue's tags. No functional change.

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 block/blk-mq-tag.c | 40 ++++++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 16 deletions(-)

diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 0dd497225c74a..58cf480df9c69 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -582,6 +582,28 @@ void blk_mq_tagset_wait_completed_request(struct blk_mq_tag_set *tagset)
 }
 EXPORT_SYMBOL(blk_mq_tagset_wait_completed_request);
 
+static void __blk_mq_hctx_tag_busy_iter(struct blk_mq_hw_ctx *hctx,
+					busy_tag_iter_fn *fn, void *priv)
+{
+	struct blk_mq_tags *tags = hctx->tags;
+
+	/*
+	 * If no software queues are currently mapped to this hardware queue,
+	 * there's nothing to check
+	 */
+	if (!blk_mq_hw_queue_mapped(hctx))
+		return;
+
+	if (tags->nr_reserved_tags)
+		bt_for_each(hctx, hctx->queue, &tags->breserved_tags, fn, priv, true);
+	bt_for_each(hctx, hctx->queue, &tags->bitmap_tags, fn, priv, false);
+}
+
 /**
  * blk_mq_queue_tag_busy_iter - iterate over all requests with a driver tag
  * @q:		Request queue to examine.
@@ -621,22 +643,8 @@ void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_tag_iter_fn *fn,
 		struct blk_mq_hw_ctx *hctx;
 		unsigned long i;
 
-		queue_for_each_hw_ctx(q, hctx, i) {
-			struct blk_mq_tags *tags = hctx->tags;
-			struct sbitmap_queue *bresv = &tags->breserved_tags;
-			struct sbitmap_queue *btags = &tags->bitmap_tags;
-
-			/*
-			 * If no software queues are currently mapped to this
-			 * hardware queue, there's nothing to check
-			 */
-			if (!blk_mq_hw_queue_mapped(hctx))
-				continue;
-
-			if (tags->nr_reserved_tags)
-				bt_for_each(hctx, q, bresv, fn, priv, true);
-			bt_for_each(hctx, q, btags, fn, priv, false);
-		}
+		queue_for_each_hw_ctx(q, hctx, i)
+			__blk_mq_hctx_tag_busy_iter(hctx, fn, priv);
 	}
 	srcu_read_unlock(&q->tag_set->tags_srcu, srcu_idx);
 	blk_queue_exit(q);
-- 
2.52.0