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 B5455C433FE for ; Tue, 21 Dec 2021 08:46:25 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4F45F6B0078; Tue, 21 Dec 2021 03:46:25 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4A4426B007B; Tue, 21 Dec 2021 03:46:25 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3928C6B007D; Tue, 21 Dec 2021 03:46:25 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0200.hostedemail.com [216.40.44.200]) by kanga.kvack.org (Postfix) with ESMTP id 291D36B0078 for ; Tue, 21 Dec 2021 03:46:25 -0500 (EST) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id E6C01180E9367 for ; Tue, 21 Dec 2021 08:46:24 +0000 (UTC) X-FDA: 78941169888.25.2DC14F8 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf01.hostedemail.com (Postfix) with ESMTP id A781C40037 for ; Tue, 21 Dec 2021 08:46:17 +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=JhiAW2eWgEksdZBxQUfFNAk6gBj2wiZNzgvEleJmSD8=; b=QRDZxGxvDhUFMF+T6jxGx19J19 gn30wGZCsdBtv/+zgpSHb7K7Zsoi/o+KotPU4iLqHWww0LyIl7X1rQluihE/9O72XX8wjWJfx2MHR dzJXGXfsrn/kLw/OLQAcDZpt0R60XE7Fu9U/wF5r2ErVfVoPT2ggfH2WK+tF6tO4U/FFhtRA5s+Ze jdtApXdW94g09RdGKwTShLv7dAkbH5BLgkjJAyp3uT0OvbTdkxYVb3GyFikW4eqZp6Bkdb+8Lropw 7XOjyy905TLjPjvi55XQ+aIUYxfywuWdnqWGx35B4v+/C0WZyA21AyBpkg9OZyeSlRTkOLCwX8008 +dZr0Q8g==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mzamp-005y59-5I; Tue, 21 Dec 2021 08:46:19 +0000 Date: Tue, 21 Dec 2021 00:46:19 -0800 From: Christoph Hellwig To: NeilBrown Cc: Trond Myklebust , Anna Schumaker , Chuck Lever , Andrew Morton , Mel Gorman , Christoph Hellwig , David Howells , linux-nfs@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 08/18] MM: Add AS_CAN_DIO mapping flag Message-ID: References: <163969801519.20885.3977673503103544412.stgit@noble.brown> <163969850302.20885.17124747377211907111.stgit@noble.brown> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <163969850302.20885.17124747377211907111.stgit@noble.brown> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Rspamd-Queue-Id: A781C40037 X-Stat-Signature: xkbxkzymqk4i5uzn5f47a8bbydogsb3j Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=QRDZxGxv; dmarc=none; spf=none (imf01.hostedemail.com: domain of BATV+1bb9050bde7847c37d79+6694+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+1bb9050bde7847c37d79+6694+infradead.org+hch@bombadil.srs.infradead.org X-Rspamd-Server: rspam02 X-HE-Tag: 1640076377-807427 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: On Fri, Dec 17, 2021 at 10:48:23AM +1100, NeilBrown wrote: > Currently various places test if direct IO is possible on a file by > checking for the existence of the direct_IO address space operation. > This is a poor choice, as the direct_IO operation may not be used - it is > only used if the generic_file_*_iter functions are called for direct IO > and some filesystems - particularly NFS - don't do this. > > Instead, introduce a new mapping flag: AS_CAN_DIO and change the various > places to check this (avoiding a pointer dereference). > unlock_new_inode() will set this flag if ->direct_IO is present, so > filesystems do not need to be changed. > > NFS *is* changed, to set the flag explicitly and discard the direct_IO > entry in the address_space_operations for files. For other can flags related to file operations we usuall stash them into file->f_mode. Any reason to treat this different?