[PATCH 43/44] pipe_get_pages(): switch to append_pipe()

[Al Viro <viro@xxxxxxxxxxxxxxxxxx>]

now that we are advancing the iterator, there's no need to
treat the first page separately - just call append_pipe()
in a loop.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
 lib/iov_iter.c | 36 ++++++++----------------------------
 1 file changed, 8 insertions(+), 28 deletions(-)

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 70736b3e07c5..a8045c97b975 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1207,10 +1207,10 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
 		   struct page ***pages, size_t maxsize, unsigned maxpages,
 		   size_t *start)
 {
-	struct pipe_inode_info *pipe = i->pipe;
-	unsigned int npages, off, count;
+	unsigned int npages, count;
 	struct page **p;
 	ssize_t left;
+	size_t off;
 
 	if (!sanity(i))
 		return -EFAULT;
@@ -1222,38 +1222,18 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
 	if (!count)
 		return -ENOMEM;
 	p = *pages;
-	left = maxsize;
-	npages = 0;
-	if (off) {
-		struct pipe_buffer *buf = pipe_buf(pipe, pipe->head - 1);
-
-		get_page(*p++ = buf->page);
-		left -= PAGE_SIZE - off;
-		if (left <= 0) {
-			buf->len += maxsize;
-			iov_iter_advance(i, maxsize);
-			return maxsize;
-		}
-		buf->len = PAGE_SIZE;
-		npages = 1;
-	}
-	for ( ; npages < count; npages++) {
-		struct page *page;
-		unsigned int size = min_t(ssize_t, left, PAGE_SIZE);
-
-		if (pipe_full(pipe->head, pipe->tail, pipe->max_usage))
-			break;
-		page = push_anon(pipe, size);
+	for (npages = 0, left = maxsize ; npages < count; npages++) {
+		struct page *page = append_pipe(i, left, &off);
 		if (!page)
 			break;
 		get_page(*p++ = page);
-		left -= size;
+		if (left <= PAGE_SIZE - off)
+			return maxsize;
+		left -= PAGE_SIZE - off;
 	}
 	if (!npages)
 		return -EFAULT;
-	maxsize -= left;
-	iov_iter_advance(i, maxsize);
-	return maxsize;
+	return maxsize - left;
 }
 
 static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa,
-- 
2.30.2