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 lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CCB41C19F28 for ; Sun, 31 Jul 2022 03:08:49 +0000 (UTC) Received: from [127.0.0.1] (helo=sfs-ml-1.v29.lw.sourceforge.com) by sfs-ml-1.v29.lw.sourceforge.com with esmtp (Exim 4.94.2) (envelope-from ) id 1oHzJt-0005st-52; Sun, 31 Jul 2022 03:08:45 +0000 Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1oHzJr-0005sm-La for linux-f2fs-devel@lists.sourceforge.net; Sun, 31 Jul 2022 03:08:43 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; 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:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=fPMMuhQS2mTvxaxxGhkKChzM2+Z43DxDxcdg+VLxe3c=; b=SrFS1ldnwmxNQp4NB3Odr1PFqh hihtIQ2AqZYwjehDoEJY49f4FurHdS6WSGtqaX31j7SBESeRPIuKVtBHoNhSb7jlBeLuqmPCwyowj 0YRTqEcAIwGlM9a5zUPUhU0Bm6NLEGbq0F3xLbaNbidUUJ9WCfpFQjOoCIp8BNfkmQ4c=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; 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:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=fPMMuhQS2mTvxaxxGhkKChzM2+Z43DxDxcdg+VLxe3c=; b=EWTIMj1RyD3eKLs5PIK1wIuxq2 9FSrh6/7ZWoBDQ4WcY9EwQLlT+5Bjwig/60n/vwSYipr8dfTq/1I0D+3Uud0u7uMN3h2xy/nVjAzl u/247OPqzTvAuEH/+P8EOo8ezwE6jvl8KMrfcIwPrN/ahayy+qnpE2oCXS90i43G9JAQ=; Received: from dfw.source.kernel.org ([139.178.84.217]) by sfi-mx-2.v28.lw.sourceforge.com with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.94.2) id 1oHzJo-0001pb-4Z for linux-f2fs-devel@lists.sourceforge.net; Sun, 31 Jul 2022 03:08:43 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1C9E260BA3 for ; Sun, 31 Jul 2022 03:08:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38810C433D6; Sun, 31 Jul 2022 03:08:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659236908; bh=tawPftnF94jyXfV2ZmURRfIrH7cFklH6ixzelkdY6vM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=q3PgaArNxgaBWU0TwQ7i9JXcghaMQBe+njO4dt2ETXSDmDPQdoUc7kkKPAs6gs3ir dKRoNbPddLaqkyzJBf/s73FN4CsT+anw/YXvcsyO97vODzyrgtyheOGsSBeR/KmFd3 l0HBiL65yvRvJLakDLqAzgOSgRFqnAguq3ahykb2UuWx2Br0IJXjZSINU5XUHTnJvy 09CG02eD4Vi3eq0o/LgIqRCQhVi6MPDIfHxhjxTBZud5EIqVn9XiZ8CCn4JlzUMk9Q cf87fjR7QKSKs8lTSQfBgORJxJjeLdihqWOr19SaKyrdWDL76pz/FbUB7a0sV6LfFe l8+AbGlYl20tw== Date: Sat, 30 Jul 2022 20:08:26 -0700 From: Jaegeuk Kim To: Eric Biggers Message-ID: References: <20220722071228.146690-1-ebiggers@kernel.org> <20220722071228.146690-7-ebiggers@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Headers-End: 1oHzJo-0001pb-4Z Subject: Re: [f2fs-dev] [PATCH v4 6/9] f2fs: don't allow DIO reads but not DIO writes X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-block@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, Keith Busch , linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On 07/25, Eric Biggers wrote: > On Sat, Jul 23, 2022 at 07:01:59PM -0700, Jaegeuk Kim wrote: > > On 07/22, Eric Biggers wrote: > > > From: Eric Biggers > > > > > > Currently, if an f2fs filesystem is mounted with the mode=lfs and > > > io_bits mount options, DIO reads are allowed but DIO writes are not. > > > Allowing DIO reads but not DIO writes is an unusual restriction, which > > > is likely to be surprising to applications, namely any application that > > > both reads and writes from a file (using O_DIRECT). This behavior is > > > also incompatible with the proposed STATX_DIOALIGN extension to statx. > > > Given this, let's drop the support for DIO reads in this configuration. > > > > IIRC, we allowed DIO reads since applications complained a lower performance. > > So, I'm afraid this change will make another confusion to users. Could > > you please apply the new bahavior only for STATX_DIOALIGN? > > > > Well, the issue is that the proposed STATX_DIOALIGN fields cannot represent this > weird case where DIO reads are allowed but not DIO writes. So the question is > whether this case actually matters, in which case we should make STATX_DIOALIGN > distinguish between DIO reads and DIO writes, or whether it's some odd edge case > that doesn't really matter, in which case we could just fix it or make > STATX_DIOALIGN report that DIO is unsupported. I was hoping that you had some > insight here. What sort of applications want DIO reads but not DIO writes? > Is this common at all? I think there's no specific application to use the LFS mode at this moment, but I'd like to allow DIO read for zoned device which will be used for Android devices. > > - Eric _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel