mm: add kiocb_wait_page_queue_init() helper

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.

Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index e053e1d..7386bc6 100644 (file)
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -533,6 +533,27 @@ static inline int wake_page_match(struct wait_page_queue *wait_page,
        return 1;
 }
 
+static inline int kiocb_wait_page_queue_init(struct kiocb *kiocb,
+                                            struct wait_page_queue *wait,
+                                            wait_queue_func_t func,
+                                            void *data)
+{
+       /* Can't support async wakeup with polled IO */
+       if (kiocb->ki_flags & IOCB_HIPRI)
+               return -EINVAL;
+       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->ki_waitq = 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_queue *wait);