[PATCH 09/11] fuse_ioctl_copy_user(): don't open-code copy_page_{to,from}_iter()

[Al Viro <viro@xxxxxxxxxxxxxxxxxx>]

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
[another cleanup, will be moved out of that branch]
 fs/fuse/file.c | 30 +++++++-----------------------
 1 file changed, 7 insertions(+), 23 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 3988b43..4c1db6c 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2339,31 +2339,15 @@ static int fuse_ioctl_copy_user(struct page **pages, 
struct iovec *iov,
 
        while (iov_iter_count(&ii)) {
                struct page *page = pages[page_idx++];
-               size_t todo = min_t(size_t, PAGE_SIZE, iov_iter_count(&ii));
-               void *kaddr;
+               size_t copied;
 
-               kaddr = kmap(page);
-
-               while (todo) {
-                       char __user *uaddr = ii.iov->iov_base + ii.iov_offset;
-                       size_t iov_len = ii.iov->iov_len - ii.iov_offset;
-                       size_t copy = min(todo, iov_len);
-                       size_t left;
-
-                       if (!to_user)
-                               left = copy_from_user(kaddr, uaddr, copy);
-                       else
-                               left = copy_to_user(uaddr, kaddr, copy);
-
-                       if (unlikely(left))
-                               return -EFAULT;
-
-                       iov_iter_advance(&ii, copy);
-                       todo -= copy;
-                       kaddr += copy;
-               }
+               if (!to_user)
+                       copied = copy_page_from_iter(page, 0, PAGE_SIZE, &ii);
+               else
+                       copied = copy_page_to_iter(page, 0, PAGE_SIZE, &ii);
 
-               kunmap(page);
+               if (unlikely(copied != PAGE_SIZE && iov_iter_count(&ii)))
+                       return -EFAULT;
        }
 
        return 0;
-- 
2.9.3