io_uring: add helper calculating region byte size

isilence · axboe · commit 4aed5b4e6d27 · 2025-11-11T07:53:33.000-07:00
There has been type related issues with region size calculation, add an
utility helper function that returns the size and handles type
conversions right.

Signed-off-by: Pavel Begunkov &lt;asml.silence@gmail.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
diff --git a/io_uring/memmap.c b/io_uring/memmap.c
@@ -134,7 +134,7 @@ static int io_region_init_ptr(struct io_mapped_region *mr)
 static int io_region_pin_pages(struct io_mapped_region *mr,
 			       struct io_uring_region_desc *reg)
 {
-	unsigned long size = mr->nr_pages << PAGE_SHIFT;
+	size_t size = io_region_size(mr);
 	struct page **pages;
 	int nr_pages;
 
@@ -154,7 +154,7 @@ static int io_region_allocate_pages(struct io_mapped_region *mr,
 				    unsigned long mmap_offset)
 {
 	gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN;
-	size_t size = (size_t) mr->nr_pages << PAGE_SHIFT;
+	size_t size = io_region_size(mr);
 	unsigned long nr_allocated;
 	struct page **pages;
 
diff --git a/io_uring/memmap.h b/io_uring/memmap.h
@@ -43,4 +43,9 @@ static inline void io_region_publish(struct io_ring_ctx *ctx,
 	*dst_region = *src_region;
 }
 
+static inline size_t io_region_size(struct io_mapped_region *mr)
+{
+	return (size_t) mr->nr_pages << PAGE_SHIFT;
+}
+
 #endif

Original file line number	Diff line number	Diff line change
`@@ -43,4 +43,9 @@ static inline void io_region_publish(struct io_ring_ctx *ctx,`
`43`	`43`	`dst_region = src_region;`
`44`	`44`	`}`
`45`	`45`
	`46`	`+static inline size_t io_region_size(struct io_mapped_region *mr)`
	`47`	`+{`
	`48`	`+ return (size_t) mr->nr_pages << PAGE_SHIFT;`
	`49`	`+}`
	`50`	`+`
`46`	`51`	`#endif`