ITER_PIPE: fold push_pipe() into __pipe_get_pages()

	Expand the only remaining call of push_pipe() (in
__pipe_get_pages()), combine it with the page-collecting loop there.

Note that the only reason it's not a loop doing append_pipe() is
that append_pipe() is advancing, while iov_iter_get_pages() is not.
As soon as it switches to saner semantics, this thing will switch
to using append_pipe().

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

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index e22c272cb420b8dbc747d36c8073da06c01b868b..bf600b4fe980a5a266c0614437e6ab1e2b578ce2 100644 (file)
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -450,46 +450,6 @@ static inline void data_start(const struct iov_iter *i,
        *offp = off;
 }
 
-static size_t push_pipe(struct iov_iter *i, size_t size,
-                       int *iter_headp, size_t *offp)
-{
-       struct pipe_inode_info *pipe = i->pipe;
-       unsigned int iter_head;
-       size_t off;
-       ssize_t left;
-
-       if (unlikely(size > i->count))
-               size = i->count;
-       if (unlikely(!size))
-               return 0;
-
-       left = size;
-       data_start(i, &iter_head, &off);
-       *iter_headp = iter_head;
-       *offp = off;
-       if (off) {
-               struct pipe_buffer *buf = pipe_buf(pipe, iter_head);
-
-               left -= PAGE_SIZE - off;
-               if (left <= 0) {
-                       buf->len += size;
-                       return size;
-               }
-               buf->len = PAGE_SIZE;
-       }
-       while (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) {
-               struct page *page = push_anon(pipe,
-                                             min_t(ssize_t, left, PAGE_SIZE));
-               if (!page)
-                       break;
-
-               left -= PAGE_SIZE;
-               if (left <= 0)
-                       return size;
-       }
-       return size - left;
-}
-
 static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
                                struct iov_iter *i)
 {
@@ -1359,23 +1319,33 @@ static inline ssize_t __pipe_get_pages(struct iov_iter *i,
                                size_t maxsize,
                                struct page **pages,
                                int iter_head,
-                               size_t *start)
+                               size_t off)
 {
        struct pipe_inode_info *pipe = i->pipe;
-       unsigned int p_mask = pipe->ring_size - 1;
-       ssize_t n = push_pipe(i, maxsize, &iter_head, start);
-       if (!n)
-               return -EFAULT;
+       ssize_t left = maxsize;
 
-       maxsize = n;
-       n += *start;
-       while (n > 0) {
-               get_page(*pages++ = pipe->bufs[iter_head & p_mask].page);
-               iter_head++;
-               n -= PAGE_SIZE;
-       }
+       if (off) {
+               struct pipe_buffer *buf = pipe_buf(pipe, iter_head);
 
-       return maxsize;
+               get_page(*pages++ = buf->page);
+               left -= PAGE_SIZE - off;
+               if (left <= 0) {
+                       buf->len += maxsize;
+                       return maxsize;
+               }
+               buf->len = PAGE_SIZE;
+       }
+       while (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) {
+               struct page *page = push_anon(pipe,
+                                             min_t(ssize_t, left, PAGE_SIZE));
+               if (!page)
+                       break;
+               get_page(*pages++ = page);
+               left -= PAGE_SIZE;
+               if (left <= 0)
+                       return maxsize;
+       }
+       return maxsize - left ? : -EFAULT;
 }
 
 static ssize_t pipe_get_pages(struct iov_iter *i,
@@ -1393,7 +1363,7 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
        npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
        capacity = min(npages, maxpages) * PAGE_SIZE - *start;
 
-       return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start);
+       return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, *start);
 }
 
 static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa,
@@ -1575,7 +1545,7 @@ static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
        p = get_pages_array(npages);
        if (!p)
                return -ENOMEM;
-       n = __pipe_get_pages(i, maxsize, p, iter_head, start);
+       n = __pipe_get_pages(i, maxsize, p, iter_head, *start);
        if (n > 0)
                *pages = p;
        else