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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 03973C25B78 for ; Wed, 22 May 2024 18:12:16 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 774396B0085; Wed, 22 May 2024 14:12:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 723C26B0088; Wed, 22 May 2024 14:12:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5EBF06B008C; Wed, 22 May 2024 14:12:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 4080A6B0085 for ; Wed, 22 May 2024 14:12:16 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id E1D83A62A4 for ; Wed, 22 May 2024 18:12:15 +0000 (UTC) X-FDA: 82146826230.04.967BA1C Received: from mail-ej1-f41.google.com (mail-ej1-f41.google.com [209.85.218.41]) by imf06.hostedemail.com (Postfix) with ESMTP id C06EA180008 for ; Wed, 22 May 2024 18:12:13 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=djAXoc+C; dmarc=none; spf=pass (imf06.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.218.41 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1716401533; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=AugUKhaYwKDJ/9b03MK/LG9RwwxS/6pxd40CuSzPjmc=; b=CvCdZ3kakVeMnawYEtPtMk1R+Vxs62fHC6mwRLekpWNs4Y7T6+krKoqk2sV62LLOCYpXiG BzaogS7QprlFHD5oS+Qqqx7Ze01LAzDXBTUPCQcVTmBNhd0e/5J5rISQuQ4/Y+6ZXl3c0u t6yRCBRrkMUcpVh/SS5Kh0+vDIZORhY= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=djAXoc+C; dmarc=none; spf=pass (imf06.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.218.41 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1716401533; a=rsa-sha256; cv=none; b=vz/qDBCA4Po+qVcChY1SCYRaYoTIpOqvp414Ag1fpZ6OnFm77V0RFLY5FaVtuwzSpbtM+w 9jR0mjBuB170kXpnDgpWQq3g6gp/RbrYPOhnVF5UAhRpHpscZi5AMqApXa3EmqOHDOYn/b c+SybpLh/l1vjwPGtZi0mW3ezg9OcoQ= Received: by mail-ej1-f41.google.com with SMTP id a640c23a62f3a-a59b81d087aso987834866b.3 for ; Wed, 22 May 2024 11:12:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; t=1716401532; x=1717006332; darn=kvack.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=AugUKhaYwKDJ/9b03MK/LG9RwwxS/6pxd40CuSzPjmc=; b=djAXoc+CCXe5shC/bE2aE1TNdupx+uEYmQkgS46I5oHaPXBY5Wt3ItbAlXvSyjuh2V S/+yYjKtFb7emPdr4C1EbaUMRb0mFg4hTNcRZ1/kmeeevs1cLFEJTJNi+64DYoLsBfnO DVR+wYZpztpwVDad/zlb9BbkfgBM+1xl6jCXw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1716401532; x=1717006332; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=AugUKhaYwKDJ/9b03MK/LG9RwwxS/6pxd40CuSzPjmc=; b=Pjk2WaU5/fcL3A/6MAOxqIOZPWmDlGkumxG+zV1pIyM76KRc64Zj9mA3wQta1tkaGb FMrr3v/VDLgEx2JZ3XyZj9RsB1VhJioOiRwBQmrosd8+MfCd75MsUGIV4zDxjsxhf3hR GlRpO9msJJa/xuz6akUnCCStxKz50kPvigfhOLOk551RdvqtajztsicBXFajz7A/b365 U60l4WNKYaETO45IozTux+JcJA3vJDhLERCV7jai0xwKlfd2tEOVi+kIMrsm063vKyVj oWeHs7eKmR7w5IOpl7M2G/eh21oTLRefgVZy+akMk1EF3oYmPgYCa7PJbqnRNJZuHama KzUg== X-Forwarded-Encrypted: i=1; AJvYcCVNoG/6tpYdIDSYwT36TKdMCfZpnHYI5K7y15c3dyglQ9lu5VGaIAEVT8xKjrXSepAvZ6Fet3Bwu+g4aG8O77TWy9c= X-Gm-Message-State: AOJu0Yw13HfIS/F1vaOIDrBOwWd94gWpAbIQtjsKoPvDDstgZjhV0mAx cb14bLf0trg2aTbU5BeMASDKt9b/FdQ0rnHtSv7lpmUfVRnEaxLJk0Muac1QZpGDaHp+/vOZGqZ EbSIMIA== X-Google-Smtp-Source: AGHT+IFqBaMt2hWEi9qvvemaextiaajfIx4YSqUQTW4Mk19+vkwtLyViKh99JupizUAZOzYKbhQnEA== X-Received: by 2002:a17:906:774e:b0:a59:b498:3ae5 with SMTP id a640c23a62f3a-a622820899emr195586766b.67.1716401531903; Wed, 22 May 2024 11:12:11 -0700 (PDT) Received: from mail-ed1-f49.google.com (mail-ed1-f49.google.com. [209.85.208.49]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a5a17b014f6sm1836899966b.145.2024.05.22.11.12.10 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 22 May 2024 11:12:10 -0700 (PDT) Received: by mail-ed1-f49.google.com with SMTP id 4fb4d7f45d1cf-56e48d0a632so14399670a12.2 for ; Wed, 22 May 2024 11:12:10 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCXtZ8plCeS9ptxTT/2sJ70UdFb1U/nbusHFkOROdQfIl3AJUvB8Ha3PMCQYcPjc3bRSAD0/YxB03SCZbCDAcECrlMo= X-Received: by 2002:a17:906:488:b0:a59:b1cf:fea0 with SMTP id a640c23a62f3a-a62280d5059mr234104266b.19.1716401530325; Wed, 22 May 2024 11:12:10 -0700 (PDT) MIME-Version: 1.0 References: <20240515091727.22034-1-laoar.shao@gmail.com> <202405221518.ecea2810-oliver.sang@intel.com> In-Reply-To: From: Linus Torvalds Date: Wed, 22 May 2024 11:11:54 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] vfs: Delete the associated dentry when deleting a file To: Matthew Wilcox Cc: kernel test robot , Yafang Shao , oe-lkp@lists.linux.dev, lkp@intel.com, Al Viro , Christian Brauner , Jan Kara , Waiman Long , Wangkai , Colin Walters , linux-fsdevel@vger.kernel.org, ying.huang@intel.com, feng.tang@intel.com, fengwei.yin@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: C06EA180008 X-Stat-Signature: u3p3ktmxd41ge49e67zxpbaigbnhn7hw X-HE-Tag: 1716401533-169274 X-HE-Meta: U2FsdGVkX197/iVu/yFdVKntyi69o6/N4oeM6Tms5o2XNPjYDFj7lQNgft/R38nTh9/9HjK0zsbRbKmUZ4/gaZPOv8gAIqvwSNykCHzhVYiJFej6fudARsw8k4+ywHJMePeNOQDMCVkrZH+PNw1g9ufBh14CMeZxNpJdvwhYrKuA9m1QsutEMJjSa+Vy8FeRfP3OyRXcemXIrLyqiavja4vrs39tLEVchcn9iTVA1n3o5dGIawGXVli4k2hMHKYD446FhbvK72mhGScKQq9dNOHW3XngsjzvBRxHy/eu0pAUNxkUTd8OYBFleA25bQMCQAPbRI8CnhrZq+yVHpXMl8tM5X7kIt0TUtYY0aco7OKPBGq+y77QTiP/JVL+xX1ehyRao4GZDkIVarQI7UKtzHRHWgvv0mCFwtLGNHbZzgXEryRA0tRZc8o3l9dvtl8r9J5HxeykqSpwOKN/6rhlfuGrPqJ5yryJHviQD2TMdHex3r1LQ92DbAT68jV9h9aEGRXPPXXC8/vq3TSbkf9au+capxR/niR0q0rIGXYWXnDe+xkErgGHfULpLv2LaS2Z80SQCiCvpRVfv92dsMXjfY2bBSFd/6Y2m/gdI7xhAUKd8711BD+hpHR/NMEMRqbyAvHLwGgwIDIyIhMGpk/kqzIFWBAcim/dLUYieqr3tDQZDCbFF41XE5DRsBmFbEzm8MHw4+rd83zb8o3vWs9iueumTsH2ld9DsJZuvBhyPT+oGbzBT3D9Mh6gz2l67fIYhx1Tmty57exh05xmChIs1jfhuQ8vy+DopM0E/1TeGU0dDOh0ktyb1eGwVTkssPLF/UGKCrnKq1yfgz9yWQtrcfcHnPNlEsh7XaDKWdxl8x8W/qXbzd3H+zTT4KmT0mITbom7CIVeycZFFmiO0kUYTdXuwWrr6puQQgq9RF4iGJ/8ADHeormSXJlCHkR+D9nFs9PfcwSXlpsCPkHqs6c cfgFO/MB 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 22 May 2024 at 10:14, Matthew Wilcox wrote: > > On Wed, May 22, 2024 at 09:00:03AM -0700, Linus Torvalds wrote: > > Of course, if you do billions of lookups of different files that do > > not exist in the same directory, I suspect you just have yourself to > > blame, so the "lots of negative lookups" load doesn't sound > > particularly realistic. > > Oh no. We have real customers that this hits and it's not even stupid. Oh, negative dentries exist, and yes, they are a major feature on some loads. Exactly because of the kinds of situations you describe. In fact, that's the _point_. Things like PATH lookup require negative dentries for good performance, because otherwise all the missed cases would force a lookup all the way out to the filesystem. So having thousands of negative dentries is normal and expected. And it will grow for bigger machines and loads, of course. That said, I don't think we've had people on real loads complain about them being in the hundreds of millions like Yafang's case. > plan9 handles this so much better because it has that union-mount stuff > instead of search paths. So it creates one dentry that tells it which of > those directories it actually exists in. But we're stuck with unix-style > search paths, so life is pain. I suspect you are just not as aware of the downsides of the plan9 models. People tend to think plan9 was great. It had huge and fundamental design mistakes. Union mounts =C3=A0 la plan9 aren't hugely wonderful, and there's a reason overlayfs does things differently (not that that is hugely wonderful either). Linus