iter_to_pipe(): switch to advancing variant of iov_iter_get_pages()

... and untangle the cleanup on failure to add into pipe.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/splice.c b/fs/splice.c
index 877290500050865bfde7dbef4a00170ea0936b50..0878b852b355caf4fa41e828a67387e2457509c6 100644 (file)
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1158,39 +1158,40 @@ static int iter_to_pipe(struct iov_iter *from,
        };
        size_t total = 0;
        int ret = 0;
-       bool failed = false;
 
-       while (iov_iter_count(from) && !failed) {
+       while (iov_iter_count(from)) {
                struct page *pages[16];
-               ssize_t copied;
+               ssize_t left;
                size_t start;
-               int n;
+               int i, n;
 
-               copied = iov_iter_get_pages(from, pages, ~0UL, 16, &start);
-               if (copied <= 0) {
-                       ret = copied;
+               left = iov_iter_get_pages2(from, pages, ~0UL, 16, &start);
+               if (left <= 0) {
+                       ret = left;
                        break;
                }
 
-               for (n = 0; copied; n++, start = 0) {
-                       int size = min_t(int, copied, PAGE_SIZE - start);
-                       if (!failed) {
-                               buf.page = pages[n];
-                               buf.offset = start;
-                               buf.len = size;
-                               ret = add_to_pipe(pipe, &buf);
-                               if (unlikely(ret < 0)) {
-                                       failed = true;
-                               } else {
-                                       iov_iter_advance(from, ret);
-                                       total += ret;
-                               }
-                       } else {
-                               put_page(pages[n]);
+               n = DIV_ROUND_UP(left + start, PAGE_SIZE);
+               for (i = 0; i < n; i++) {
+                       int size = min_t(int, left, PAGE_SIZE - start);
+
+                       buf.page = pages[i];
+                       buf.offset = start;
+                       buf.len = size;
+                       ret = add_to_pipe(pipe, &buf);
+                       if (unlikely(ret < 0)) {
+                               iov_iter_revert(from, left);
+                               // this one got dropped by add_to_pipe()
+                               while (++i < n)
+                                       put_page(pages[i]);
+                               goto out;
                        }
-                       copied -= size;
+                       total += ret;
+                       left -= size;
+                       start = 0;
                }
        }
+out:
        return total ? total : ret;
 }