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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E852EB64D9 for ; Mon, 19 Jun 2023 20:44:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229802AbjFSUoC (ORCPT ); Mon, 19 Jun 2023 16:44:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41480 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229649AbjFSUoA (ORCPT ); Mon, 19 Jun 2023 16:44:00 -0400 Received: from mail-pl1-x631.google.com (mail-pl1-x631.google.com [IPv6:2607:f8b0:4864:20::631]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2469A128 for ; Mon, 19 Jun 2023 13:43:59 -0700 (PDT) Received: by mail-pl1-x631.google.com with SMTP id d9443c01a7336-1b50a419ab6so7391175ad.1 for ; Mon, 19 Jun 2023 13:43:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20221208.gappssmtp.com; s=20221208; t=1687207438; x=1689799438; h=content-transfer-encoding:subject:from:cc:to:content-language :user-agent:mime-version:date:message-id:from:to:cc:subject:date :message-id:reply-to; bh=oC2tnKZazU9uVlrm2A6bHgfVySKOOyCWLXqbM4UiIQg=; b=kvelQzVi3hjDhJ1f6AVzfGp4bEg7VBq0/Kn4byBa3sy4DWm4qYGLhlwvefXJHzaSAH yT5c5FOdH3jVm57CXHlBChTiBmL3YHLNLW4ZEF04V/daCQnP1a/Xev0jF+bSPjAQT7Gu YLmmjJmXlAcBojdHAOIFxWUzrn0Gt5VQn4IS0O4KHbHCntWNOKHdsk39JZfkyZ64axvg uXc0ZnSEhoN9BQjkCmfDiu2cUPXmE+JefJTynZpqiJqxI5lCQBteEL9hLXR+eYRj3oAB txCrK2O6dwC23NlqPRISzEaglytnQ+4KIO8GWEwk7AtFsagi5u92HtrerIid610iZJuc b55Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1687207438; x=1689799438; h=content-transfer-encoding:subject:from:cc:to:content-language :user-agent:mime-version:date:message-id:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=oC2tnKZazU9uVlrm2A6bHgfVySKOOyCWLXqbM4UiIQg=; b=VIaArHjetmE+RzzhdHln5+/Sfsl8TFmjBT6udTE3qfcHf1LpT38y7mbQIzBAh4DhhG QbCRqXtq7NLMFyuAy2T4zgtZi2se9CnilhYvnS2CnZtGmvIGo1hvH7UQ9Wzrc0zYNRsh 7xkzCycZ30CJ7cMdne6p86Aa/bVuX4DBTMXPgwnjGyCCPxtVkW+k209+6nH1bt5EcJGF RLM5pyxsYoyINXM1rXMuX2JHCDy0M2Bu8QCLMC28SU1VlCS9z19SQ6/5BxdWW5By/51P 76s9GtFQMk+ZVZhMVvwrhPAmUWwkixLSiJRRc0f6V85nb07p5KyqJCpEuvU+s4xJ5fOK zLDg== X-Gm-Message-State: AC+VfDy+wcFmBEwD6mUsTEgCe5zBd+GfCZn4vTmLQ+CoIcia4zQYwrm9 90kEF6A7POEu8wNVANksBBAaMScZljy9RMINPRA= X-Google-Smtp-Source: ACHHUZ5dDre5JtwuZeS25jOuzOzvltt1rhev/GGrypbNGHP5rit3XtWQeaKUe6C2Iv3OsmxEJsi0GA== X-Received: by 2002:a17:903:1105:b0:1b3:ebda:654e with SMTP id n5-20020a170903110500b001b3ebda654emr12740048plh.5.1687207438599; Mon, 19 Jun 2023 13:43:58 -0700 (PDT) Received: from [192.168.1.136] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id jl17-20020a170903135100b001a65fa33e62sm235362plb.154.2023.06.19.13.43.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 Jun 2023 13:43:57 -0700 (PDT) Message-ID: <1dc1a0f2-9be4-8ae0-da26-3c00c8a71b41@kernel.dk> Date: Mon, 19 Jun 2023 14:43:56 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Content-Language: en-US To: Yangtao Li Cc: Jaegeuk Kim , Lu Hongfei , linux-f2fs-devel@lists.sourceforge.net, LKML From: Jens Axboe Subject: f2fs async buffered write patch Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I came across this patch in a news posting: https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git/commit/?h=dev&id=d618126911829523e35a61f4a5a4ad159b1b2c8d which has me a bit worried. As far as I can tell, all that patch does is set FMODE_BUF_WASYNC, and then just hope that the lower layers handle the rest? What happens if iocb->ki_flags & IOCB_NOWAIT is true, and now we do: generic_perform_write(iocb, from) ... ->write_begin() <- does this block? ... ->write_end() <- or this one? ... balance_dirty_pages_ratelimited() <- this one surely does... If you look just one level down the latter to balance_dirty_pages_ratelimited_flags(), you'll even see the 'flags' argument documented there. This looks pretty haphazard and cannot possibly work as-is, so please get this reverted until f2fs is converted to iomap, or IOCB_NOWAIT is handled by generic_perform_write() and below. -- Jens Axboe