diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 95c56d42505b..402d49688a16 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -845,27 +845,27 @@ static inline void pipe_truncate(struct iov_iter *i)
 static void pipe_advance(struct iov_iter *i, size_t size)
 {
 	struct pipe_inode_info *pipe = i->pipe;
-	if (size) {
-		struct pipe_buffer *buf;
-		unsigned int p_mask = pipe->ring_size - 1;
-		unsigned int i_head = i->head;
-		size_t off = i->iov_offset, left = size;
+	unsigned int off = i->iov_offset;
 
-		if (off) /* make it relative to the beginning of buffer */
-			left += off - pipe->bufs[i_head & p_mask].offset;
-		while (1) {
-			buf = &pipe->bufs[i_head & p_mask];
-			if (left <= buf->len)
-				break;
-			left -= buf->len;
-			i_head++;
-		}
-		i->head = i_head;
-		i->iov_offset = buf->offset + left;
+	if (!off && !size) {
+		pipe_discard_from(pipe, i->start_head); // discard everything
+		return;
 	}
 	i->count -= size;
-	/* ... and discard everything past that point */
-	pipe_truncate(i);
+	while (1) {
+		struct pipe_buffer *buf = pipe_buf(pipe, i->head);
+		if (off) /* make it relative to the beginning of buffer */
+			size += off - buf->offset;
+		if (size <= buf->len) {
+			buf->len = size;
+			i->iov_offset = buf->offset + size;
+			break;
+		}
+		size -= buf->len;
+		i->head++;
+		off = 0;
+	}
+	pipe_discard_from(pipe, i->head + 1); // discard everything past this one
 }
 
 static void iov_iter_bvec_advance(struct iov_iter *i, size_t size)