linux-kernel - [PATCH 14/15] mm: add kiocb_wait_page_queue

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Message-Id: <20200618144355.17324-15-axboe@kernel.dk>
Date:   Thu, 18 Jun 2020 08:43:54 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     io-uring@...r.kernel.org
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, akpm@...ux-foundation.org,
        Jens Axboe <axboe@...nel.dk>,
        Johannes Weiner <hannes@...xchg.org>
Subject: [PATCH 14/15] 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@...xchg.org>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
---
 include/linux/pagemap.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index e053e1d9a4d7..7386bc67cc5a 100644
--- 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);
-- 
2.27.0