Merge tag 'pull-work.iov_iter-rebased' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull more iov_iter updates from Al Viro:

 - more new_sync_{read,write}() speedups - ITER_UBUF introduction

 - ITER_PIPE cleanups

 - unification of iov_iter_get_pages/iov_iter_get_pages_alloc and
   switching them to advancing semantics

 - making ITER_PIPE take high-order pages without splitting them

 - handling copy_page_from_iter() for high-order pages properly

* tag 'pull-work.iov_iter-rebased' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (32 commits)
  fix copy_page_from_iter() for compound destinations
  hugetlbfs: copy_page_to_iter() can deal with compound pages
  copy_page_to_iter(): don't split high-order page in case of ITER_PIPE
  expand those iov_iter_advance()...
  pipe_get_pages(): switch to append_pipe()
  get rid of non-advancing variants
  ceph: switch the last caller of iov_iter_get_pages_alloc()
  9p: convert to advancing variant of iov_iter_get_pages_alloc()
  af_alg_make_sg(): switch to advancing variant of iov_iter_get_pages()
  iter_to_pipe(): switch to advancing variant of iov_iter_get_pages()
  block: convert to advancing variants of iov_iter_get_pages{,_alloc}()
  iov_iter: advancing variants of iov_iter_get_pages{,_alloc}()
  iov_iter: saner helper for page array allocation
  fold __pipe_get_pages() into pipe_get_pages()
  ITER_XARRAY: don't open-code DIV_ROUND_UP()
  unify the rest of iov_iter_get_pages()/iov_iter_get_pages_alloc() guts
  unify xarray_get_pages() and xarray_get_pages_alloc()
  unify pipe_get_pages() and pipe_get_pages_alloc()
  iov_iter_get_pages(): sanity-check arguments
  iov_iter_get_pages_alloc(): lift freeing pages array on failure exits into wrapper
  ...

1 files changed, 26 insertions, 28 deletions

diff --git a/fs/splice.c b/fs/splice.c
index 93a2c9bf6249..0878b852b355 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -301,11 +301,9 @@ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
 {
 	struct iov_iter to;
 	struct kiocb kiocb;
-	unsigned int i_head;
 	int ret;
 
 	iov_iter_pipe(&to, READ, pipe, len);
-	i_head = to.head;
 	init_sync_kiocb(&kiocb, in);
 	kiocb.ki_pos = *ppos;
 	ret = call_read_iter(in, &kiocb, &to);
@@ -313,9 +311,8 @@ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
 		*ppos = kiocb.ki_pos;
 		file_accessed(in);
 	} else if (ret < 0) {
-		to.head = i_head;
-		to.iov_offset = 0;
-		iov_iter_advance(&to, 0); /* to free what was emitted */
+		/* free what was emitted */
+		pipe_discard_from(pipe, to.start_head);
 		/*
 		 * callers of ->splice_read() expect -EAGAIN on
 		 * "can't put anything in there", rather than -EFAULT.
@@ -1161,39 +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;
 }