From patchwork Fri May 22 20:57:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Axboe X-Patchwork-Id: 11566175 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 14914912 for ; Fri, 22 May 2020 20:57:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9B14207CB for ; Fri, 22 May 2020 20:57:28 +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="0fvIuQQn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731039AbgEVU5Z (ORCPT ); Fri, 22 May 2020 16:57:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57836 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730963AbgEVU5Y (ORCPT ); Fri, 22 May 2020 16:57:24 -0400 Received: from mail-pf1-x442.google.com (mail-pf1-x442.google.com [IPv6:2607:f8b0:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1B8C3C08C5C0 for ; Fri, 22 May 2020 13:57:23 -0700 (PDT) Received: by mail-pf1-x442.google.com with SMTP id z26so5711269pfk.12 for ; Fri, 22 May 2020 13:57:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=h1P/xo8AaX3jjKt86a2Y3pBxxtNUWegSfV+Hhuz+jdk=; b=0fvIuQQnbJWtjugF4UCX5gQtYykfEWNXVl847bXb9v5zQ1p4X2EGBrdtM+o2A0LEgN YLRaBUdaLUa50GjkG1ZBMnZx8/PIQvIcTc1ixjjj/oGm33TgnTSoaOATtQvITIlNMQp1 I7cYEFSv4tnXPrK9EMG++P+uqEo4VSe1Q6hJ7/pbC2za2nD7fZtAp7ta+mROxdBF/DPP bBJQocZli2Z4TtzB7/DnGQ7U6MJ5T+HfG4K5R9v1ARgstiV80JaqqKCUbyB6wcL0hA1r K0OWaeNCwLQ0bLl1ENxDGo3twoYkeVra4noiBRdWQRvlLvht3xy6sDbAaAfgvsNtNJI3 8ZqA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=h1P/xo8AaX3jjKt86a2Y3pBxxtNUWegSfV+Hhuz+jdk=; b=VZzMLhRVQ4D/7mx1xlXeBQVCcIbUgFWTzSG91Km6MtY2gABiaWMs/QBurPSBwbSNe9 NMd0ggdW17aepn9jTdS/7nzEanjtRNT2JZ979QuLnfRKnzd3gx9WJ0MOPxfVD9gTyk68 GX+1FfXxs5MeBNLyKD+2Xo/+Mj/VNjhEl8TN7Wh80Tz+nSShyzd22omuDBNMjwFlX0Jz HphM+kgqGRBvMGReFmLo/Dt8efhUJAk0UOtwGZWq3pUgFeousVFitel2Gm3+yhIMPRuM 0D+xVyJnBR+j9taShas2HwSRumi7eq59rFAkahmD6H/nmWNjgHALpBrM25MMoOPEEkt6 ntxA== X-Gm-Message-State: AOAM533YDaGgptGrltTk96ZNGKU7WGNcqUsCIYBoSsdROAU5IpaBBYsc b7dxuKo1kSzrL7L0NGd+7/zN74d7Myc= X-Google-Smtp-Source: ABdhPJwqZOezu8aVuOxmNjbD2ILSdyDll2DILbLtdsTm9YD/gHE6euUwuS3QA3EPTkgeG8sgNaq/rg== X-Received: by 2002:aa7:9532:: with SMTP id c18mr5642306pfp.255.1590181042363; Fri, 22 May 2020 13:57:22 -0700 (PDT) Received: from ?IPv6:2605:e000:100e:8c61:e0db:da55:b0a4:601? ([2605:e000:100e:8c61:e0db:da55:b0a4:601]) by smtp.gmail.com with ESMTPSA id n205sm7738080pfd.50.2020.05.22.13.57.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 May 2020 13:57:21 -0700 (PDT) Subject: [PATCH v2 03/11] mm: add support for async page locking To: io-uring@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20200522202311.10959-1-axboe@kernel.dk> <20200522202311.10959-4-axboe@kernel.dk> From: Jens Axboe Message-ID: <43ad2c54-1e42-35ed-26be-6535cb0541b6@kernel.dk> Date: Fri, 22 May 2020 14:57:20 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200522202311.10959-4-axboe@kernel.dk> Content-Language: en-US Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 5/22/20 2:23 PM, Jens Axboe wrote: > 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 use the iocb->private field to pass in this necessary data for this > to happen. struct wait_page_key is made public, and we define struct > wait_page_async as the interface between the caller and the core. I did some reshuffling of this patch before sending it out, and I ended up sending a previous version. Please look at this one instead. commit d8f0a0bfc4a0742cb461287561b956bc56e90976 Author: Jens Axboe Date: Fri May 22 09:12:09 2020 -0600 mm: add support for async page locking 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 use the iocb->private field to pass in this necessary data for this to happen. 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 diff --git a/include/linux/fs.h b/include/linux/fs.h index 7e84d823c6a8..82b989695ab9 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->private holds wait_page_async struct */ +#define IOCB_WAITQ (1 << 8) struct kiocb { struct file *ki_filp; diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index a8f7bd8ea1c6..e260bcd071e4 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -456,8 +456,21 @@ static inline pgoff_t linear_page_index(struct vm_area_struct *vma, return pgoff; } +/* This has the same layout as wait_bit_key - see fs/cachefiles/rdwr.c */ +struct wait_page_key { + struct page *page; + int bit_nr; + int page_match; +}; + +struct wait_page_async { + struct wait_queue_entry wait; + struct wait_page_key key; +}; + 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); extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm, unsigned int flags); extern void unlock_page(struct page *page); @@ -494,6 +507,14 @@ static inline int lock_page_killable(struct page *page) return 0; } +static inline int lock_page_async(struct page *page, + struct wait_page_async *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 80747f1377d5..ebee7350ea3b 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -990,13 +990,6 @@ void __init pagecache_init(void) page_writeback_init(); } -/* This has the same layout as wait_bit_key - see fs/cachefiles/rdwr.c */ -struct wait_page_key { - struct page *page; - int bit_nr; - int page_match; -}; - struct wait_page_queue { struct page *page; int bit_nr; @@ -1210,6 +1203,33 @@ 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_async *wait) +{ + struct wait_queue_head *q = page_waitqueue(page); + int ret = 0; + + wait->key.page = page; + wait->key.bit_nr = PG_locked; + + spin_lock_irq(&q->lock); + if (PageLocked(page)) { + __add_wait_queue_entry_tail(q, &wait->wait); + SetPageWaiters(page); + ret = -EIOCBQUEUED; + } + spin_unlock_irq(&q->lock); + return ret; +} + +static int wait_on_page_locked_async(struct page *page, + struct wait_page_async *wait) +{ + if (!PageLocked(page)) + return 0; + return __wait_on_page_locked_async(compound_head(page), wait); +} + /** * put_and_wait_on_page_locked - Drop a reference and wait for it to be unlocked * @page: The page to wait for. @@ -1372,6 +1392,11 @@ int __lock_page_killable(struct page *__page) } EXPORT_SYMBOL_GPL(__lock_page_killable); +int __lock_page_async(struct page *page, struct wait_page_async *wait) +{ + return wait_on_page_locked_async(page, wait); +} + /* * Return values: * 1 - page is locked; mmap_sem is still held.