From patchwork Thu Jun 18 14:43:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Axboe X-Patchwork-Id: 11612369 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 24966159A for ; Thu, 18 Jun 2020 14:45:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0708120897 for ; Thu, 18 Jun 2020 14:45:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="nPiXsRi6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731136AbgFROpn (ORCPT ); Thu, 18 Jun 2020 10:45:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57384 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730931AbgFROoK (ORCPT ); Thu, 18 Jun 2020 10:44:10 -0400 Received: from mail-pf1-x443.google.com (mail-pf1-x443.google.com [IPv6:2607:f8b0:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8547BC06179A for ; Thu, 18 Jun 2020 07:44:09 -0700 (PDT) Received: by mail-pf1-x443.google.com with SMTP id d66so2884307pfd.6 for ; Thu, 18 Jun 2020 07:44:09 -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:reply-to :mime-version:content-transfer-encoding; bh=ugefse5kKTqXQ4eIaIDMHVyZsS3OmAuYWslFQFrKGAg=; b=nPiXsRi6BRt5JXEn23LLT0VlfowWc9FFrkRNPpQKyLz9yJSlB/8/wAL82qAGNedSkF cFv9Mr/dmOS/jD0ExP7JdeFsVG0cpLkPOn+Mv46eMO76ZpXYm8G+eaVtyJaSY5qfTAid FGe99XxOvLrha9M1k68N9nt6NIVNYnuM6FbUXYkyHG4WXFzvEDR8h5yR+ORXQIzt6rOY nlAC2fElI7Ax5Ja40mz8CQ3+pneQvvbUW7ssoIRcg++V8szsXNlw7tYb2iFTM3zhNZ0R BV6S7vWTAo03tso3K4liAsMATX93QS+pb1jxyiHuCxXSSpR0IvQ9l4/kjEcYZ79DaA9F dzDQ== 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:reply-to:mime-version:content-transfer-encoding; bh=ugefse5kKTqXQ4eIaIDMHVyZsS3OmAuYWslFQFrKGAg=; b=SChT1JbvEmSMph3IHWYd/bszA8BgfvYLyAdKSCxNhDdX+EHt7aLm2OhxQZT4FBE+ls 2t1thKftfLsobVXj5TW/lTrhHGMsxiTg8iK3WogjTYtvyoRF/f7LPNXWUuC+Y0SnNdjy xHynQURenhUv7HanCWWjP0XpXvVLiB6cG3l/mYO0klfMNiMjKi+eiNTcenYOMm5v3h+T SEkp3/X6/cgQSkdFnzDfL6BOH+gRpYHzXUnqNUMYeUlZLCOyXYIkHPgKgP6WeMzm4gAG 9QKKklCbH16veShb4+yeJrKCV9ACNpE5myPAXlY7A+hyT1HIoE7mXwn9sxkPj5aWPiuX JjBw== X-Gm-Message-State: AOAM531fNm/BGRxmQ6IdOZ2g1NKgiQl0nLatO1p7uTBqxehI0U0YrgMA 5ofVYCld5E1CsZJ/iVv6H0asyA== X-Google-Smtp-Source: ABdhPJzwVrGYYhzPh7B/cl4K86rqVhqHG34HLw3paGpNlY/2JChA4DR4YVjWC/vOkk6B5Jf1Y+/RRQ== X-Received: by 2002:a63:d858:: with SMTP id k24mr3368619pgj.288.1592491448987; Thu, 18 Jun 2020 07:44:08 -0700 (PDT) Received: from x1.localdomain ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id g9sm3127197pfm.151.2020.06.18.07.44.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Jun 2020 07:44:08 -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 , Johannes Weiner Subject: [PATCH 07/15] mm: add support for async page locking Date: Thu, 18 Jun 2020 08:43:47 -0600 Message-Id: <20200618144355.17324-8-axboe@kernel.dk> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200618144355.17324-1-axboe@kernel.dk> References: <20200618144355.17324-1-axboe@kernel.dk> Reply-To: "[PATCHSET v7 0/15]"@vger.kernel.org, Add@vger.kernel.org, support@vger.kernel.org, for@vger.kernel.org, async@vger.kernel.org, buffered@vger.kernel.org, reads@vger.kernel.org MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@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. Acked-by: Johannes Weiner Signed-off-by: Jens Axboe --- include/linux/fs.h | 7 ++++++- include/linux/pagemap.h | 17 ++++++++++++++++ mm/filemap.c | 45 ++++++++++++++++++++++++++++++++++++++++- 3 files changed, 67 insertions(+), 2 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 6c4ab4dc1cd7..6ac919b40596 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -315,6 +315,8 @@ 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; @@ -328,7 +330,10 @@ 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 2f18221bb5c8..e053e1d9a4d7 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -535,6 +535,7 @@ 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); @@ -571,6 +572,22 @@ static inline int lock_page_killable(struct page *page) return 0; } +/* + * lock_page_async - Lock the page, unless this would block. If the page + * is already locked, then queue a callback when the page becomes unlocked. + * This callback can then retry the operation. + * + * Returns 0 if the page is locked successfully, or -EIOCBQUEUED if the page + * was already locked and the callback defined in 'wait' was queued. + */ +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 c3175dbd8fba..e8aaf43bee9f 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1180,6 +1180,36 @@ 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); + __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. @@ -1342,6 +1372,11 @@ 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_lock is still held. @@ -2131,6 +2166,11 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb, } readpage: + if (iocb->ki_flags & IOCB_NOWAIT) { + unlock_page(page); + put_page(page); + goto would_block; + } /* * A previous I/O error may have been due to temporary * failures, eg. multipath errors. @@ -2150,7 +2190,10 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb, } if (!PageUptodate(page)) { - error = lock_page_killable(page); + if (iocb->ki_flags & IOCB_WAITQ) + error = lock_page_async(page, iocb->ki_waitq); + else + error = lock_page_killable(page); if (unlikely(error)) goto readpage_error; if (!PageUptodate(page)) {