iomap: switch iomap_page_mkwrite to use iomap_iter

Switch iomap_page_mkwrite to use iomap_iter.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

fs/iomap/buffered-io.c

@@ -961,15 +961,15 @@ iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
 }
 EXPORT_SYMBOL_GPL(iomap_truncate_page);
 
-static loff_t
-iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
-		void *data, struct iomap *iomap, struct iomap *srcmap)
+static loff_t iomap_page_mkwrite_iter(struct iomap_iter *iter,
+		struct page *page)
 {
-	struct page *page = data;
+	loff_t length = iomap_length(iter);
 	int ret;
 
-	if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
-		ret = __block_write_begin_int(page, pos, length, NULL, iomap);
+	if (iter->iomap.flags & IOMAP_F_BUFFER_HEAD) {
+		ret = __block_write_begin_int(page, iter->pos, length, NULL,
+					      &iter->iomap);
 		if (ret)
 			return ret;
 		block_commit_write(page, 0, length);
@@ -983,29 +983,24 @@ iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
 
 vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
 {
+	struct iomap_iter iter = {
+		.inode		= file_inode(vmf->vma->vm_file),
+		.flags		= IOMAP_WRITE | IOMAP_FAULT,
+	};
 	struct page *page = vmf->page;
-	struct inode *inode = file_inode(vmf->vma->vm_file);
-	unsigned long length;
-	loff_t offset;
 	ssize_t ret;
 
 	lock_page(page);
-	ret = page_mkwrite_check_truncate(page, inode);
+	ret = page_mkwrite_check_truncate(page, iter.inode);
 	if (ret < 0)
 		goto out_unlock;
-	length = ret;
-
-	offset = page_offset(page);
-	while (length > 0) {
-		ret = iomap_apply(inode, offset, length,
-				IOMAP_WRITE | IOMAP_FAULT, ops, page,
-				iomap_page_mkwrite_actor);
-		if (unlikely(ret <= 0))
-			goto out_unlock;
-		offset += ret;
-		length -= ret;
-	}
+	iter.pos = page_offset(page);
+	iter.len = ret;
+	while ((ret = iomap_iter(&iter, ops)) > 0)
+		iter.processed = iomap_page_mkwrite_iter(&iter, page);
 
+	if (ret < 0)
+		goto out_unlock;
 	wait_for_stable_page(page);
 	return VM_FAULT_LOCKED;
 out_unlock: