[PATCH 10/11] mm: add kiocb_wait_page_async_init() helper

[Jens Axboe]

Checks if the file supports it, and initializes the values that we need.
Caller passes in 'data' pointer, if any, and the callback function to
be used.

Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
 include/linux/pagemap.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 39af9f890866..dec61e9e5710 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -468,6 +468,24 @@ struct wait_page_async {
 	struct wait_page_key key;
 };
 
+static inline int kiocb_wait_page_async_init(struct kiocb *kiocb,
+					     struct wait_page_async *wait,
+					     wait_queue_func_t func,
+					     void *data)
+{
+	if (kiocb->ki_filp->f_mode & FMODE_BUF_RASYNC) {
+		wait->wait.func = func;
+		wait->wait.private = data;
+		wait->wait.flags = 0;
+		INIT_LIST_HEAD(&wait->wait.entry);
+		kiocb->ki_flags |= IOCB_WAITQ;
+		kiocb->private = wait;
+		return 0;
+	}
+
+	return -EOPNOTSUPP;
+}
+
 extern void __lock_page(struct page *page);
 extern int __lock_page_killable(struct page *page);
 extern int __lock_page_async(struct page *page, struct wait_page_async *wait);
-- 
2.26.2