From e3b42964f84c028f352c11269661d47f6ca4ab2e Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sat, 11 Jun 2022 02:52:03 -0400 Subject: [PATCH] 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 --- lib/iov_iter.c | 80 ++++++++++++++++++---------------------------------------- 1 file changed, 25 insertions(+), 55 deletions(-) diff --git a/lib/iov_iter.c b/lib/iov_iter.c index e22c272..bf600b4 100644 --- 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 -- 2.7.4