On 2020/5/15 12:19, Matthew Wilcox wrote:

On Thu, May 07, 2020 at 03:50:57PM +0800, Zhen Lei wrote:

quoted

+++ b/block/blk-settings.c

@@ -150,7 +150,7 @@ void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_secto
 	unsigned int max_sectors;
 
 	if ((max_hw_sectors << 9) < PAGE_SIZE) {
-		max_hw_sectors = 1 << (PAGE_SHIFT - 9);
+		max_hw_sectors = PAGE_SECTORS;

Surely this should be:

	if (max_hw_sectors < PAGE_SECTORS) {
		max_hw_sectors = PAGE_SECTORS;

... no?

I've noticed this place before. "(max_hw_sectors << 9) < PAGE_SIZE" can also make sure
that max_hw_sectors is not too large, that means (max_hw_sectors << 9) may overflow.

quoted

-	page = read_mapping_page(mapping,
-			(pgoff_t)(n >> (PAGE_SHIFT - 9)), NULL);
+	page = read_mapping_page(mapping, (pgoff_t)sectors_to_npage(n), NULL);

... again, get the type right, and you won't need the cast.

OK, I'll consider it.

.