From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DBF5AC433E3 for ; Tue, 26 May 2020 19:51:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B744120B80 for ; Tue, 26 May 2020 19:51:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="iE3qXf/O" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389124AbgEZTvf (ORCPT ); Tue, 26 May 2020 15:51:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40498 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390293AbgEZTve (ORCPT ); Tue, 26 May 2020 15:51:34 -0400 Received: from mail-pj1-x1041.google.com (mail-pj1-x1041.google.com [IPv6:2607:f8b0:4864:20::1041]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E3DCC03E96F for ; Tue, 26 May 2020 12:51:33 -0700 (PDT) Received: by mail-pj1-x1041.google.com with SMTP id q9so264089pjm.2 for ; Tue, 26 May 2020 12:51:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=91LPx4VFG9btmYMQhwNjB8l3CSYHzquXTBOwjvdo+tY=; b=iE3qXf/OK07yvdsW8Vb51ZnFfsRrhY/I8AyPsPZBuYDCG+TC8jz9R0D0M+GRoONqmI gim5npZm8cxTM+QSweOQXfZsODg5VS6+7bN+CKZ4dMY7gY+QpgkMzMrv59Fphw7RYayS JBGmAVIX3BEE46Smv2GYnsm+ImSrUvQiaACUJ58syDnlB+HNG5sK2LsdT4XG1F3dqp/4 oVhakRyiZ0nYbu4FXaNA5/FJOFFKKsGpp/Hce7YkE5gJePG3prwbUWapZwHq23NDXkHD /0mpwLPbH1DZDuHuFhnGHadUwVq75hkc8cYWz+Lkln7BqwK/1OvfBTdLVjGY87S3aO6Z QMtg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=91LPx4VFG9btmYMQhwNjB8l3CSYHzquXTBOwjvdo+tY=; b=Nda8GplDn/7lXdumdqWwo9SytqtuWL8T/FHkYDrMEyzl1JPj3F8HfZAbC6YheFxkG5 Us8S99149F3F+2HRKFdJvvlnE7yGJIc+BAXv0b/ck1Su70uN2My/va1ND16puRrBMR/K Lh3zs0Bm+xRpt4XJy0nZlJXweqy4RumU4w/IEghgNYZtwnMPe6XCCUIXHrtXMsd+Z1Uc Jq+LaiBFl3bn+H/ktbZadfHsVKdLwibjJmGj2dwyDcX6BuZewWHJ8mY44KFPD0ed9FLK 3q3K1Oe3OGuHtnRCscxx71c9YtVNCDHzDH4MFOu/dewLGKFm09E0i8crQQzHZHiRANDO XRzg== X-Gm-Message-State: AOAM5337D27GqgM5UtpI3bRfmOhQ/N+uiaTRpUUZxtpdlHVuyFes8SU7 TQXNbVtJtHA0gB0GrzZLhx9tWjdXK5zUqw== X-Google-Smtp-Source: ABdhPJzk5ZeLZ9PiNns9o7WtuSDeeuU8oJZ8JIZZ0HjXadMCEeQTkM4QJqeJe1UnHKeyrNQoGn1fyg== X-Received: by 2002:a17:90a:2a0d:: with SMTP id i13mr909880pjd.94.1590522691575; Tue, 26 May 2020 12:51:31 -0700 (PDT) Received: from x1.lan ([2605:e000:100e:8c61:94bb:59d2:caf6:70e1]) by smtp.gmail.com with ESMTPSA id c184sm313943pfc.57.2020.05.26.12.51.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 26 May 2020 12:51:31 -0700 (PDT) From: Jens Axboe To: io-uring@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, Jens Axboe Subject: [PATCH 04/12] mm: add support for async page locking Date: Tue, 26 May 2020 13:51:15 -0600 Message-Id: <20200526195123.29053-5-axboe@kernel.dk> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200526195123.29053-1-axboe@kernel.dk> References: <20200526195123.29053-1-axboe@kernel.dk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Normally waiting for a page to become unlocked, or locking the page, requires waiting for IO to complete. Add support for lock_page_async() and wait_on_page_locked_async(), which are callback based instead. This allows a caller to get notified when a page becomes unlocked, rather than wait for it. We add a new iocb field, ki_waitq, to pass in the necessary data for this to happen. We can unionize this with ki_cookie, since that is only used for polled IO. Polled IO can never co-exist with async callbacks, as it is (by definition) polled completions. struct wait_page_key is made public, and we define struct wait_page_async as the interface between the caller and the core. Signed-off-by: Jens Axboe --- include/linux/fs.h | 7 ++++++- include/linux/pagemap.h | 9 +++++++++ mm/filemap.c | 41 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 56 insertions(+), 1 deletion(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index d3ebb49189df..ba1fff0e7bca 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -314,6 +314,8 @@ enum rw_hint { #define IOCB_SYNC (1 << 5) #define IOCB_WRITE (1 << 6) #define IOCB_NOWAIT (1 << 7) +/* iocb->ki_waitq is valid */ +#define IOCB_WAITQ (1 << 8) struct kiocb { struct file *ki_filp; @@ -327,7 +329,10 @@ struct kiocb { int ki_flags; u16 ki_hint; u16 ki_ioprio; /* See linux/ioprio.h */ - unsigned int ki_cookie; /* for ->iopoll */ + union { + unsigned int ki_cookie; /* for ->iopoll */ + struct wait_page_queue *ki_waitq; /* for async buffered IO */ + }; randomized_struct_fields_end }; diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 53d980f2208d..d3e63c9c61ae 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -495,6 +495,7 @@ static inline int wake_page_match(struct wait_page_queue *wait_page, 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); extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm, unsigned int flags); extern void unlock_page(struct page *page); @@ -531,6 +532,14 @@ static inline int lock_page_killable(struct page *page) return 0; } +static inline int lock_page_async(struct page *page, + struct wait_page_queue *wait) +{ + if (!trylock_page(page)) + return __lock_page_async(page, wait); + return 0; +} + /* * lock_page_or_retry - Lock the page, unless this would block and the * caller indicated that it can handle a retry. diff --git a/mm/filemap.c b/mm/filemap.c index e891b5bee8fd..c746541b1d49 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1183,6 +1183,42 @@ int wait_on_page_bit_killable(struct page *page, int bit_nr) } EXPORT_SYMBOL(wait_on_page_bit_killable); +static int __wait_on_page_locked_async(struct page *page, + struct wait_page_queue *wait, bool set) +{ + struct wait_queue_head *q = page_waitqueue(page); + int ret = 0; + + wait->page = page; + wait->bit_nr = PG_locked; + + spin_lock_irq(&q->lock); + if (set) + ret = !trylock_page(page); + else + ret = PageLocked(page); + if (ret) { + __add_wait_queue_entry_tail(q, &wait->wait); + SetPageWaiters(page); + if (set) + ret = !trylock_page(page); + else + ret = PageLocked(page); + /* + * If we were succesful now, we know we're still on the + * waitqueue as we're still under the lock. This means it's + * safe to remove and return success, we know the callback + * isn't going to trigger. + */ + if (!ret) + __remove_wait_queue(q, &wait->wait); + else + ret = -EIOCBQUEUED; + } + spin_unlock_irq(&q->lock); + return ret; +} + /** * put_and_wait_on_page_locked - Drop a reference and wait for it to be unlocked * @page: The page to wait for. @@ -1345,6 +1381,11 @@ int __lock_page_killable(struct page *__page) } EXPORT_SYMBOL_GPL(__lock_page_killable); +int __lock_page_async(struct page *page, struct wait_page_queue *wait) +{ + return __wait_on_page_locked_async(page, wait, true); +} + /* * Return values: * 1 - page is locked; mmap_sem is still held. -- 2.26.2