From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 274281A5B92; Thu, 12 Jun 2025 03:56:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749700579; cv=none; b=QpHUPO6FqNxkpCDvR19tAaZ9/YTwCSvrtgG4TmiPSVkPfPVBOHivXV4XExoofnWu7neENkUKwZMGTuYD6Xud1qmksMdcMGZrNs6HB6LMtL95zqm+9Z+GwK5AqLyKcieZM9lFeLsiU60RuDk2/z9CpNGgQwZSkf+6GRhjki1UkW8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749700579; c=relaxed/simple; bh=UslVktwU7O+RBLcks1oVqzu726D8U18Bzt3PyiMDTU4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FUQ7XQkk+78uqiO8bzWSF9AP7PmIa6+07MSZmEyeybYKpgD6twUTopz4GbKUqkdPZtLdsLqMNKei8gQBVwNt3lzcH4hfHVO51/ZPS/GEltICvLiCGGM5YnkTOI6sdVM+uKvcl4RIlyR/IfCnASsM4/wm8EBuYLEw5s+3sWwbV5c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QpzvQUCQ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="QpzvQUCQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8EAE9C4CEEA; Thu, 12 Jun 2025 03:56:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749700578; bh=UslVktwU7O+RBLcks1oVqzu726D8U18Bzt3PyiMDTU4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=QpzvQUCQH5Rm9CTAgGM8tvClbtdmZwQB/+Vvj/275Ox6mmZj1xOLeqB1QRsJwAhdt IDtQyrMZIEsdA/kQVoQEFESvRhf0+J2UfAvJA6fIpFhUtavfHVnNm1jFnzfsp/lnaE yU5y9g2dtIVjNUky/OChjqszE6FKWDsUVuUr4BWljhJJCQccDQ5746W2EdYMvOH8ft xiaRJDjGCl1HaZ1YYzTmlguyDuVNwZeL8FFndmqHalQGZv1vpGKV4jQG04U7cEFRe3 LZ6jkM86Y0b5O0ctlev/Ciqfd9wHc5ygoF2E0dIzwmJ7qQGA9c94/As4G4ogN2YlQi X7Enbp/7TdSZg== Date: Wed, 11 Jun 2025 20:56:18 -0700 From: "Darrick J. Wong" To: Christoph Hellwig Cc: Joanne Koong , miklos@szeredi.hu, brauner@kernel.org, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, bernd.schubert@fastmail.fm, kernel-team@meta.com Subject: Re: [PATCH v1 4/8] iomap: add writepages support for IOMAP_IN_MEM iomaps Message-ID: <20250612035618.GJ6138@frogsfrogsfrogs> References: <20250606233803.1421259-1-joannelkoong@gmail.com> <20250606233803.1421259-5-joannelkoong@gmail.com> <20250609165741.GK6156@frogsfrogsfrogs> Precedence: bulk X-Mailing-List: linux-fsdevel@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 Mon, Jun 09, 2025 at 08:49:25PM -0700, Christoph Hellwig wrote: > On Mon, Jun 09, 2025 at 09:57:41AM -0700, Darrick J. Wong wrote: > > > It might also be worth stating what you don't use. One big thing > > > that springs to mind is ioends. Which are really useful if you > > > need more than one request to handle a folio, something that is > > > pretty common in network file systems. I guess you don't need > > > that for fuse? > > > > My initial thought was "I wonder if Joanne would be better off with a > > totally separate iomap_writepage_map_blocks implementation" > > I think that's basically what the patches do, right? Yes. > > since I > > *think* fuse just needs a callback from iomap to initiate FUSE_WRITE > > calls on the dirty range(s) of a folio, and then fuse can call > > mapping_set_error and iomap_finish_folio_write when those FUSE_WRITE > > calls complete. There are no bios, so I don't see much point in using > > the ioend machinery. > > Note that the mapping_set_error in iomap_writepage_map is only for > synchronous errors for mapping setup anyway, all the actual I/O error > are handled asynchronously anyway. Similar, clearing the writeback > bit only happens for synchronous erorr, or the rare case of (almost) > synchronous I/O. Heheh, my brain has gotten fuzzy on all that pagecache error handling changes over the years. --D