io_uring/memmap: account memory before pinning

Move memory accounting before page pinning. It shouldn't even try to pin
pages if it's not allowed, and accounting is also relatively
inexpensive. It also give a better code structure as we do generic
accounting and then can branch for different mapping types.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1e242b8038411a222e8b269d35e021fa5015289f.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 a0416733e92136de6d00c1ec37e5b6c98cd0c268..fca93bc4c6f13196f0f5337acd431764dc067363 100644 (file)
--- a/io_uring/memmap.c
+++ b/io_uring/memmap.c
@@ -252,17 +252,21 @@ int io_create_region(struct io_ring_ctx *ctx, struct io_mapped_region *mr,
        if (check_add_overflow(reg->user_addr, reg->size, &end))
                return -EOVERFLOW;
 
-       pages = io_pin_pages(reg->user_addr, reg->size, &nr_pages);
-       if (IS_ERR(pages))
-               return PTR_ERR(pages);
-
+       nr_pages = reg->size >> PAGE_SHIFT;
        if (ctx->user) {
                ret = __io_account_mem(ctx->user, nr_pages);
                if (ret)
-                       goto out_free;
+                       return ret;
                pages_accounted = nr_pages;
        }
 
+       pages = io_pin_pages(reg->user_addr, reg->size, &nr_pages);
+       if (IS_ERR(pages)) {
+               ret = PTR_ERR(pages);
+               pages = NULL;
+               goto out_free;
+       }
+
        vptr = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);
        if (!vptr) {
                ret = -ENOMEM;
@@ -277,7 +281,8 @@ int io_create_region(struct io_ring_ctx *ctx, struct io_mapped_region *mr,
 out_free:
        if (pages_accounted)
                __io_unaccount_mem(ctx->user, pages_accounted);
-       io_pages_free(&pages, nr_pages);
+       if (pages)
+               io_pages_free(&pages, nr_pages);
        return ret;
 }