io_uring/rsrc: cleanup io_pin_pages()

This function is overly convoluted with a goto error path, and checks
under the mmap_read_lock() that don't need to be at all. Rearrange it
a bit so the checks and errors fall out naturally, rather than needing
to jump around for it.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index d9c853d105878027d5ad727803eb80c672847d10..7034be555334d2fe51c17a56ca6bb3b1e3981ac0 100644 (file)
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -1037,39 +1037,36 @@ struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages)
 {
        unsigned long start, end, nr_pages;
        struct page **pages = NULL;
-       int pret, ret = -ENOMEM;
+       int ret;
 
        end = (ubuf + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
        start = ubuf >> PAGE_SHIFT;
        nr_pages = end - start;
+       WARN_ON(!nr_pages);
 
        pages = kvmalloc_array(nr_pages, sizeof(struct page *), GFP_KERNEL);
        if (!pages)
-               goto done;
+               return ERR_PTR(-ENOMEM);
 
-       ret = 0;
        mmap_read_lock(current->mm);
-       pret = pin_user_pages(ubuf, nr_pages, FOLL_WRITE | FOLL_LONGTERM,
-                             pages);
-       if (pret == nr_pages)
+       ret = pin_user_pages(ubuf, nr_pages, FOLL_WRITE | FOLL_LONGTERM, pages);
+       mmap_read_unlock(current->mm);
+
+       /* success, mapped all pages */
+       if (ret == nr_pages) {
                *npages = nr_pages;
-       else
-               ret = pret < 0 ? pret : -EFAULT;
+               return pages;
+       }
 
-       mmap_read_unlock(current->mm);
-       if (ret) {
+       /* partial map, or didn't map anything */
+       if (ret >= 0) {
                /* if we did partial map, release any pages we did get */
-               if (pret > 0)
-                       unpin_user_pages(pages, pret);
-               goto done;
-       }
-       ret = 0;
-done:
-       if (ret < 0) {
-               kvfree(pages);
-               pages = ERR_PTR(ret);
+               if (ret)
+                       unpin_user_pages(pages, ret);
+               ret = -EFAULT;
        }
-       return pages;
+       kvfree(pages);
+       return ERR_PTR(ret);
 }
 
 static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,