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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0146AC433F5 for ; Thu, 28 Oct 2021 14:19:15 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A87C5610FC for ; Thu, 28 Oct 2021 14:19:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org A87C5610FC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 42BC26B006C; Thu, 28 Oct 2021 10:19:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3DABE6B0071; Thu, 28 Oct 2021 10:19:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2A2CE940007; Thu, 28 Oct 2021 10:19:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0032.hostedemail.com [216.40.44.32]) by kanga.kvack.org (Postfix) with ESMTP id 056896B006C for ; Thu, 28 Oct 2021 10:19:13 -0400 (EDT) Received: from smtpin33.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 75155181894E5 for ; Thu, 28 Oct 2021 14:19:13 +0000 (UTC) X-FDA: 78746053386.33.78DE092 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf26.hostedemail.com (Postfix) with ESMTP id AA27620019F2 for ; Thu, 28 Oct 2021 14:19:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=qBYvabBzUrmfcwMkMp4699k+QSkrdWrgSn+jwNNlusU=; b=4v86oPQHA1+wLH9XP+zcWkpp93 oAH1vxjvEni54qeWnn+/zn48QkFsg4bbJslfbVuLu4fEUGx5htY+3Q95VHLqaAulTk4GaSmavoZAm n9DSeW2xE7pWwPFv5U7MwZY/G2Z0yl7VRpFKI2CMtd1wyM7UxocgU1Jkf7eBSeAn3tt1EX2K7+pYN noz/qV8RDFn5pcyR3xRkETbgdjDl3GqpZpdxfv7i7PBppF55ceIOmzRumGpE75wNyEPJUnDEh/iDJ 28HpfCSvTjEgomNS8cMYpZCsFSp/CBN9zwqbdzJwVPg7m9lObrptct8ym6dIpW4CmSyrrB/mRz98C 9P0pQQgA==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mg6FJ-00868c-R8; Thu, 28 Oct 2021 14:19:09 +0000 Date: Thu, 28 Oct 2021 07:19:09 -0700 From: Christoph Hellwig To: Jens Axboe Cc: Andrew Morton , Dave Chinner , "linux-fsdevel@vger.kernel.org" , Linux Memory Management List , Chris Mason , Pavel Begunkov Subject: Re: mm: don't read i_size of inode unless we need it Message-ID: References: <6b67981f-57d4-c80e-bc07-6020aa601381@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6b67981f-57d4-c80e-bc07-6020aa601381@kernel.dk> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Stat-Signature: hpsdc68t48k8kmo53i9pxamy7ob78ud7 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: AA27620019F2 Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=4v86oPQH; dmarc=none; spf=none (imf26.hostedemail.com: domain of BATV+ef71c33bf9b69cad04e0+6640+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+ef71c33bf9b69cad04e0+6640+infradead.org+hch@bombadil.srs.infradead.org X-HE-Tag: 1635430753-735798 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: Btw, given that you're micro-optimizing in this area: block devices still use ->direct_IO in the I/O path. It might make sense to switch to the model of the file systems that use iomap where we avoid that indirect call and can optimize the code for the direct I/O fast path. With that you woudn't even end up using this i_size_read at all