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 X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C7A2C433E6 for ; Sat, 2 Jan 2021 13:26:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 184E0224F4 for ; Sat, 2 Jan 2021 13:26:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726671AbhABN0b (ORCPT ); Sat, 2 Jan 2021 08:26:31 -0500 Received: from mail.kernel.org ([198.145.29.99]:37198 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726636AbhABN03 (ORCPT ); Sat, 2 Jan 2021 08:26:29 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id DAABD224D4; Sat, 2 Jan 2021 13:25:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1609593949; bh=nQptyWsIb5DLXUAZK2xe+ITycsezO9g8NVJXR3oAkm4=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=V8EdnLsyWJKT9bxjUp5n2zEUvpNVcnHpEfJIqpZDfNqU45WzeiJl8WvVsEgET8JHK /MVvoFy59bzktC95YX/+LAyH8bLYWXWeHkY7lH4U6P6SsonscRHCHaax+eg9iMUqD9 v1gIa20v6BIikhb4H69COOpMBsWH+Cui7dHtXXKfYCBpABidWvd8W1u6kX5Q9GBTNu CXapbNzjaj3Tv8XDY3ZlBmLtolpfRL4btczqchZk7XxD10IrWH4XWjDzHkSh1UseNT NTdvu/kgGU+iU9SxlWZcJlLdS5Z4rgFBEtVYnv0gwJY9wlQ0q1vrkR/FQDWCCdSnSn RE9wGmXcJOF+A== Message-ID: Subject: Re: [PATCH 3/3] overlayfs: Report writeback errors on upper From: Jeff Layton To: Matthew Wilcox , Amir Goldstein Cc: Sargun Dhillon , Vivek Goyal , linux-fsdevel , linux-kernel , overlayfs , Miklos Szeredi , Jan Kara , NeilBrown , Al Viro , Christoph Hellwig , Chengguang Xu Date: Sat, 02 Jan 2021 08:25:46 -0500 In-Reply-To: <20201228204837.GA28221@casper.infradead.org> References: <20201223200746.GR874@casper.infradead.org> <20201223202140.GB11012@ircssh-2.c.rugged-nimbus-611.internal> <20201223204428.GS874@casper.infradead.org> <20201224121352.GT874@casper.infradead.org> <1334bba9cefa81f80005f8416680afb29044379c.camel@kernel.org> <20201228155618.GA6211@casper.infradead.org> <5bc11eb2e02893e7976f89a888221c902c11a2b4.camel@kernel.org> <20201228204837.GA28221@casper.infradead.org> Content-Type: text/plain; charset="ISO-8859-15" User-Agent: Evolution 3.38.2 (3.38.2-1.fc33) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2020-12-28 at 20:48 +0000, Matthew Wilcox wrote: > On Mon, Dec 28, 2020 at 09:37:37PM +0200, Amir Goldstein wrote: > > Having said that, I never objected to the SEEN flag split. > > I STRONGLY object to the SEEN flag split. I think it is completely > unnecessary and nobody's shown me a use-case that changes my mind. I think the flag split makes better sense conceptually, though the existing callers don't really have a need for it. I have a use-case in mind that doesn't really involve overlayfs: We still have a lot of internal callers that ultimately call filemap_check_errors() to check and clear the mapping's AS_EIO/AS_ENOSPC flags. Splitting the SEEN flag in two could allow those callers to instead sample the errseq_t using errseq_peek for their own purposes, without clearing the REPORTED flag. That means that the existing semantics for seeing errors on newly opened files could be preserved while allowing internal callers to use errseq_t-based error handling. That said, I don't have any patches to do this right now. It's a fairly significant project to convert all of the existing callers of filemap_check_errors() to such a scheme wholesale. It could be done piecemeal though, and we could start discouraging new callers of filemap_check_errors and the like. -- Jeff Layton