io_uring/memmap: helper for pinning region pages

In preparation to adding kernel allocated regions extract a new helper
that pins user pages.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a17d7c39c3de4266b66b75b2dcf768150e1fc618.1732886067.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/memmap.c b/io_uring/memmap.c
index fd348c98f64fa97d859c72b1aca5c6848cfbe471..5d261e07c2e32cb1378ac749d0dcd907415fbbc6 100644 (file)
--- a/io_uring/memmap.c
+++ b/io_uring/memmap.c
@@ -246,10 +246,28 @@ static int io_region_init_ptr(struct io_mapped_region *mr)
        return 0;
 }
 
+static int io_region_pin_pages(struct io_ring_ctx *ctx,
+                               struct io_mapped_region *mr,
+                               struct io_uring_region_desc *reg)
+{
+       unsigned long size = mr->nr_pages << PAGE_SHIFT;
+       struct page **pages;
+       int nr_pages;
+
+       pages = io_pin_pages(reg->user_addr, size, &nr_pages);
+       if (IS_ERR(pages))
+               return PTR_ERR(pages);
+       if (WARN_ON_ONCE(nr_pages != mr->nr_pages))
+               return -EFAULT;
+
+       mr->pages = pages;
+       mr->flags |= IO_REGION_F_USER_PROVIDED;
+       return 0;
+}
+
 int io_create_region(struct io_ring_ctx *ctx, struct io_mapped_region *mr,
                     struct io_uring_region_desc *reg)
 {
-       struct page **pages;
        int nr_pages, ret;
        u64 end;
 
@@ -278,13 +296,9 @@ int io_create_region(struct io_ring_ctx *ctx, struct io_mapped_region *mr,
        }
        mr->nr_pages = nr_pages;
 
-       pages = io_pin_pages(reg->user_addr, reg->size, &nr_pages);
-       if (IS_ERR(pages)) {
-               ret = PTR_ERR(pages);
+       ret = io_region_pin_pages(ctx, mr, reg);
+       if (ret)
                goto out_free;
-       }
-       mr->pages = pages;
-       mr->flags |= IO_REGION_F_USER_PROVIDED;
 
        ret = io_region_init_ptr(mr);
        if (ret)