[PATCH 3/5] blk-mq: add helpers for allocating/freeing pages of request pool

[Ming Lei <ming.lei@xxxxxxxxxx>]

Add two helpers for allocating and freeing pages of request pool.

No function change.

Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxx>
Cc: Bart Van Assche <bvanassche@xxxxxxx>
Cc: John Garry <john.garry@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
---
 block/blk-mq.c | 81 +++++++++++++++++++++++++++++++-------------------
 1 file changed, 51 insertions(+), 30 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 5019d21e7ff8..65f73b8db477 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2275,6 +2275,53 @@ static int blk_mq_get_hw_queue_node(struct blk_mq_tag_set *set,
 	return node;
 }
 
+static size_t order_to_size(unsigned int order)
+{
+	return (size_t)PAGE_SIZE << order;
+}
+
+static struct page *blk_mq_alloc_rqs_page(int node, unsigned order,
+		unsigned min_size)
+{
+	struct page *page;
+	unsigned this_order = order;
+
+	do {
+		page = alloc_pages_node(node,
+			GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
+			this_order);
+		if (page)
+			break;
+		if (!this_order--)
+			break;
+		if (order_to_size(this_order) < min_size)
+			break;
+	} while (1);
+
+	if (!page)
+		return NULL;
+
+	page->private = this_order;
+
+	/*
+	 * Allow kmemleak to scan these pages as they contain pointers
+	 * to additional allocations like via ops->init_request().
+	 */
+	kmemleak_alloc(page_address(page), order_to_size(this_order), 1, GFP_NOIO);
+
+	return page;
+}
+
+static void blk_mq_free_rqs_page(struct page *page)
+{
+	/*
+	 * Remove kmemleak object previously allocated in
+	 * blk_mq_alloc_rqs().
+	 */
+	kmemleak_free(page_address(page));
+	__free_pages(page, page->private);
+}
+
 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
 		     unsigned int hctx_idx)
 {
@@ -2296,12 +2343,7 @@ void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
 	while (!list_empty(&tags->page_list)) {
 		page = list_first_entry(&tags->page_list, struct page, lru);
 		list_del_init(&page->lru);
-		/*
-		 * Remove kmemleak object previously allocated in
-		 * blk_mq_alloc_rqs().
-		 */
-		kmemleak_free(page_address(page));
-		__free_pages(page, page->private);
+		blk_mq_free_rqs_page(page);
 	}
 }
 
@@ -2348,11 +2390,6 @@ struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
 	return tags;
 }
 
-static size_t order_to_size(unsigned int order)
-{
-	return (size_t)PAGE_SIZE << order;
-}
-
 static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
 			       unsigned int hctx_idx, int node)
 {
@@ -2396,30 +2433,14 @@ int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
 		while (this_order && left < order_to_size(this_order - 1))
 			this_order--;
 
-		do {
-			page = alloc_pages_node(node,
-				GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
-				this_order);
-			if (page)
-				break;
-			if (!this_order--)
-				break;
-			if (order_to_size(this_order) < rq_size)
-				break;
-		} while (1);
-
+		page = blk_mq_alloc_rqs_page(node, this_order, rq_size);
 		if (!page)
 			goto fail;
 
-		page->private = this_order;
+		this_order = (int)page->private;
 		list_add_tail(&page->lru, &tags->page_list);
-
 		p = page_address(page);
-		/*
-		 * Allow kmemleak to scan these pages as they contain pointers
-		 * to additional allocations like via ops->init_request().
-		 */
-		kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
+
 		entries_per_page = order_to_size(this_order) / rq_size;
 		to_do = min(entries_per_page, depth - i);
 		left -= to_do * rq_size;
-- 
2.25.2