From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6FD5F2D6E66; Fri, 22 May 2026 03:53:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779422015; cv=none; b=U/YrYNFoye7eC1EJywlNighflbbIylzobshAuTSBjRft6IZpU57BWq2Vpd5Bqd+JPHY6Fprmk7NHz6snRmXCPYF+pkhGiRq+BBZg19qIU3CAGcMyEfbBMqY0hlRTuSG+2GTKhd6ySQuBk0PLFIus6kKmlNRm7F1/3RnGU8N9wZw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779422015; c=relaxed/simple; bh=z8xJgwMXu4yr5/7Jz4e9+O7bv7Cb81vDb98T8Xt0Qpc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=s45uWY2vvgI4+Z3vngT5s6cXzWT33x8jj6SvOJSJVIdEidKh8bftvu2ASYeKQ4UmUyKCLpdrXB2e6fSZUJZJHGUHlrb/BGHJ6KPsYzAUP4jjZX7J/WtVMXxMZvH1ndpy8vWPvuWn4okKXzFKRAEqnVDwjTwaD0+KAWSg+p5h3zc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fld1ypw9; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fld1ypw9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63CA61F000E9; Fri, 22 May 2026 03:53:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779422014; bh=kB9u/fd5oqOyzn/d56rzTMKcyf+Gut0U9mtxblKihAQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=fld1ypw9APN84jvJm1OOVi3+ZHhpiCqzC8QK3ifg0qLQZgEH8RQwQdH9O+qgnCYrc Sl4P80xhdmTewu6/ueUPwz49MOXYxB6UBItK5OTQ0jNrXM+RhuWFzcbq8/AWs+iJAF sWwz/T9UUHbDSE6lBJmFzuV/C0rrwCCV/lVPg4G1C8T1NTPTVkDkijsvMe8RDW8nZA LZLL7Urvwe4SUWrAFQbjev8VcLMOGCOX2SkHENYXY+5glXf5Ca4NrlNsci9Of0Z5lp wuu95IWJCelZn/vv77Jo3iZBmgg6TAwqcTk9PAgwVxz35w1q73aBen2fJCrKohTcUa sPyncu6PC/Yqw== Date: Thu, 21 May 2026 22:53:31 -0500 From: Eric Biggers To: Jaegeuk Kim Cc: Theodore Tso , Christoph Hellwig , linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Matthew Wilcox , linux-f2fs-devel@lists.sourceforge.net, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Akilesh Kailash , Christian Brauner Subject: Re: [f2fs-dev] [PATCH v2] f2fs: another way to set large folio by remembering inode number Message-ID: <20260522035331.GE5937@quark> References: <20260409134538.3692605-1-jaegeuk@kernel.org> <20260521155748.GA79343@macsyma-wired.lan> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, May 22, 2026 at 03:32:39AM +0000, Jaegeuk Kim wrote: > On 05/21, Theodore Tso wrote: > > On Thu, May 21, 2026 at 01:51:08AM -0700, Christoph Hellwig wrote: > > > > You haven't sent a proposal. This is a reply to a reply to a reply of a > > > > patch. There's no justification for why f2fs is so special that it > > > > needs this. What the hell is going on? You know this is not the way to > > > > get code merged into Linux. > > > > > > None of this got properly answers, and this broken interface now landed > > > in linux-next. IT is offloading a user.* xattr which is free-form > > > user data with semantics that are weird to say it very nicely. > > > > > > All this was done against the advice in the mailing list discussion. > > > > So let me get this straight. This is a magic xattr interface which is > > not even persisted in the file system, but instead sets a 32-bit > > bitmask in the struct inode which disappears once the inode gets > > flushed from the inode stack. And it uses a generic xattr name, > > "user.fadvise". > > > > There's no way in *hell* any other file system is likely to adopt such > > a broken interface, so why didn't you just use an ioctl to set this > > magic f2fs-specific flag? > > I went this route because Android heavily restricts ioctl() permissions > and we needed broader access for this to work within the framework. It's straightforward (2 lines I think) to update Android's SELinux policy to allow an ioctl in all domains. So that doesn't seem like a reason to not use an ioctl. In fact this is actually a reason *to* use an ioctl, as it shows that ioctls can be allowed/denied independently as needed, whereas xattrs just use the file write permission. - Eric