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 53A84C7EE2A for ; Mon, 30 Jun 2025 06:41:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C6AD66B0099; Mon, 30 Jun 2025 02:41:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C42506B009A; Mon, 30 Jun 2025 02:41:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B7F6C6B009B; Mon, 30 Jun 2025 02:41:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id A75EB6B0099 for ; Mon, 30 Jun 2025 02:41:21 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 2BB09105B68 for ; Mon, 30 Jun 2025 06:41:21 +0000 (UTC) X-FDA: 83611120362.20.84BCFAD Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf10.hostedemail.com (Postfix) with ESMTP id 4BC3AC0002 for ; Mon, 30 Jun 2025 06:41:18 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=ZejtL3sm ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1751265679; a=rsa-sha256; cv=none; b=qNcm0zIbpZj+4w0ssof5Q5oVOzfpJdwbbkfpVIZFY3DIZZZwFN6659lVFWKMFRXL/Ln+QS 6bYOD8p53VGvVfw6AVFkpQwTnrsBCShfs0opicugGzZ1hpmrm7HsFSw/+vdowib5lqKYoa WGDXvmaFzriXoOE7Q2Dh82topxstymo= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=ZejtL3sm; dmarc=none; spf=none (imf10.hostedemail.com: domain of BATV+6fdead0dd008edde6601+7981+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+6fdead0dd008edde6601+7981+infradead.org+hch@bombadil.srs.infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1751265679; 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=EGTTLrFnUeqEt2LkPOIc08Ji7tLkFOls0h+QkE/PVjc=; b=hsAVGj6kNlMwjj9jCmSIelMpiU+WLC0IzLObbLtMPUhj5ZMAhFHIW/htOO+5xb01dv84ED GhXCZe2uruET2yWiZUErSZLgWAe8e85ldinYLwGQ6+fJ3FE6uJGXcFRHd8u1+sTP1zwR0N XykQH477P3YGlWxD/MHoTBgEm3+SxCw= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=EGTTLrFnUeqEt2LkPOIc08Ji7tLkFOls0h+QkE/PVjc=; b=ZejtL3sm8QRhn8xcCFFNMRUL5+ 0p7qJLSYpjYurp0fqdmTke9LZp+wa5u/DPr2M2a4rWyOnqixEjMud8JtVP9k/ud3+EzI567qwEmKl 2mNIqLQPd4psFOKCKguyQ/Em0h9PQKYZNBoWsnq7ml1C9HrGmd8yap79ONNpYS5/CxtR90oliYys5 S0NpLfICJfIyRoYslKnSAh47MCq1iELTLHWXmbbfwyfLY/UyKQiB2AReAz55sg3bfb0JTKFF7mU6Y LhVeWFX7hDzkKSoHGg2nslJ9BLS5KGSoJWZdNRQka+3RT+Y//LfBZlQzUxjZ1EDkVNgRUv4GWaBPM bptOJZKg==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uW8CX-00000001MDX-03Ey; Mon, 30 Jun 2025 06:41:13 +0000 Date: Sun, 29 Jun 2025 23:41:12 -0700 From: "hch@infradead.org" To: Matthew Wilcox Cc: =?utf-8?B?6ZmI5rab5rab?= Taotao Chen , "tytso@mit.edu" , "hch@infradead.org" , "adilger.kernel@dilger.ca" , "brauner@kernel.org" , "jani.nikula@linux.intel.com" , "rodrigo.vivi@intel.com" , "tursulin@ursulin.net" , "airlied@gmail.com" , "linux-fsdevel@vger.kernel.org" , "linux-ext4@vger.kernel.org" , "linux-block@vger.kernel.org" , "intel-gfx@lists.freedesktop.org" , "dri-devel@lists.freedesktop.org" , "linux-mm@kvack.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "chentao325@qq.com" , "frank.li@vivo.com" Subject: Re: [PATCH v3 4/4] ext4: support uncached buffered I/O Message-ID: References: <20250627110257.1870826-1-chentaotao@didiglobal.com> <20250627110257.1870826-5-chentaotao@didiglobal.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Stat-Signature: cd586mjcycqdub8517kzom63gwgar4ue X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 4BC3AC0002 X-Rspam-User: X-HE-Tag: 1751265678-623903 X-HE-Meta: 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 smilpRYE uJC1Ud1nfcEabXSEryYPW0pRA/NbmJgJbdA68ru3eCpPXNNYUvL0WGxG+bBdciSSBMrgZLDdaSevFPNaQJnpwmSaTOluiN6GScPThwTiefGI2UXw+DLMNbMl0zD+FK+jSkSOwtzXqaynRQvd7BiAQG0/b0L/5UFRiwTLdfK90LcKZU5mHQW8Ru8sARw== 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 Fri, Jun 27, 2025 at 06:03:09PM +0100, Matthew Wilcox wrote: > On Fri, Jun 27, 2025 at 11:03:13AM +0000, 陈涛涛 Taotao Chen wrote: > > +++ b/fs/ext4/inode.c > > @@ -1270,6 +1270,9 @@ static int ext4_write_begin(const struct kiocb *iocb, > > if (unlikely(ret)) > > return ret; > > > > + if (iocb->ki_flags & IOCB_DONTCACHE) > > + fgp |= FGP_DONTCACHE; > > I think this needs to be: > > if (iocb && iocb->ki_flags & IOCB_DONTCACHE) > > because it's legit to call write_begin with a NULL argument. The > 'file' was always an optional argument, and we should preserve that > optionality with this transformation. write_begin and write_end are only callbacks through helpers called by the file system. So if the file system never passes a NULL file/kiocb it doesn't need to check for it. > I wonder if it's worth abstracting some of this boilerplate. Something > like: > > struct folio *write_begin_get_folio(iocb, mapping, index, len) > { > fgf_t fgflags = FGP_WRITEBEGIN; > > if (iocb && iocb->ki_flags & IOCB_DONTCACHE) > fgflags |= FGP_DONTCACHE; > fgflags |= fgf_set_order(len); > > return __filemap_get_folio(mapping, index, fgflags, > mapping_gfp_mask(mapping)); > } But this helper still seems useful.