copy_page_to_iter(): don't split high-order page in case of ITER_PIPE

... just shove it into one pipe_buffer.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 46ec07886d7b937ffa6b397380f6cb4a41aac84e..4e3696d349a484acb5e8e4ae4546d8f078dcfdeb 100644 (file)
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -706,30 +706,21 @@ static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
        return false;
 }
 
-static size_t __copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
-                        struct iov_iter *i)
-{
-       if (unlikely(iov_iter_is_pipe(i))) {
-               return copy_page_to_iter_pipe(page, offset, bytes, i);
-       } else {
-               void *kaddr = kmap_local_page(page);
-               size_t wanted = _copy_to_iter(kaddr + offset, bytes, i);
-               kunmap_local(kaddr);
-               return wanted;
-       }
-}
-
 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
                         struct iov_iter *i)
 {
        size_t res = 0;
        if (unlikely(!page_copy_sane(page, offset, bytes)))
                return 0;
+       if (unlikely(iov_iter_is_pipe(i)))
+               return copy_page_to_iter_pipe(page, offset, bytes, i);
        page += offset / PAGE_SIZE; // first subpage
        offset %= PAGE_SIZE;
        while (1) {
-               size_t n = __copy_page_to_iter(page, offset,
-                               min(bytes, (size_t)PAGE_SIZE - offset), i);
+               void *kaddr = kmap_local_page(page);
+               size_t n = min(bytes, (size_t)PAGE_SIZE - offset);
+               n = _copy_to_iter(kaddr + offset, n, i);
+               kunmap_local(kaddr);
                res += n;
                bytes -= n;
                if (!bytes || !n)