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.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 C6412CDE008 for ; Fri, 26 Jun 2026 04:31:23 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4gmjRZ1Hd0z2yYd; Fri, 26 Jun 2026 14:31:22 +1000 (AEST) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=213.95.11.211 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1782448282; cv=none; b=h5Ll5R3RH+MpO9tJolqxzegWaFFZDDewF1neopDgO/Xd2TkNpr1ht9k4RvjaocnM0qo8I6y4ToYEHP+aOTFcpooSn2gVuG9CEp2NUs+Ta23XoQ1Q4aF3cMisKHIRPjUVfE7gdrmo2orfPrG4o5Kgwo0Bm6zdLhaFusA0CiFt0Y0cL/Tu+5PILjqMRj3ZvB33W34VSduGztssWuVFSb7WYVdhy9R2MJopNDtItsrVDDs1lyVL7bkUNjqOuztSrxEMy3G1iNClYaHUc62zwvj7xIP87P7KoDMBzW4DgDUwWnI0cp232g9mpg0QCm3ADLjxvh7eThzrtGQ8WkgrRVkNSw== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1782448282; c=relaxed/relaxed; bh=EEU3xELJqHidlkaHSvcWmH5JF+Sp/Xnst3OP92YZemU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QHxCxlfAWJgQWQR6dyLqjDqeYA815N+z79q2rU1Ezm9HKVE4/f5hze5XKlSZ9vkaEzZYIyf9g6zD3yR4iF+qzjxL6ovn4xFP3YxISYAYs2lW/N1JiLO2EZWBM4mjHNSgPnfRWXk75TywoxTWkUxEezetHfqZpc15i2PVBC/g1kTR3s6kS1CskVnK/BvJvaS2dg8sHQdDomnB/2yzrST/HHRP64n+99xkMTWT/N+7+Cbwyq58neqK6b/OLfNtOWLov0YHzkQ4UeqB2q6/mq+ShnESsj2XjCUzH77NAeBNLPoah26OtzUA/gpgc/R+flQm2gUD5vL1XvzItHTxm5Lg2w== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=lst.de; spf=pass (client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de; receiver=lists.ozlabs.org) smtp.mailfrom=lst.de Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=lst.de Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de; receiver=lists.ozlabs.org) Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4gmjRY3nLHz2yVv for ; Fri, 26 Jun 2026 14:31:21 +1000 (AEST) Received: by verein.lst.de (Postfix, from userid 2407) id C8F7368B05; Fri, 26 Jun 2026 06:31:17 +0200 (CEST) Date: Fri, 26 Jun 2026 06:31:17 +0200 From: Christoph Hellwig To: "Darrick J. Wong" Cc: Christoph Hellwig , Christian Brauner , Kelu Ye , Yifan Zhao , Ritesh Harjani , Joanne Koong , Namjae Jeon , Sungjong Seo , Hyunchul Lee , Konstantin Komarov , Miklos Szeredi , fuse-devel@lists.linux.dev, ntfs3@lists.linux.dev, linux-erofs@lists.ozlabs.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 2/2] iomap: submit read bio after each extent Message-ID: <20260626043117.GB8078@lst.de> References: <20260625120803.2462291-1-hch@lst.de> <20260625120803.2462291-3-hch@lst.de> <20260625174758.GE6078@frogsfrogsfrogs> X-Mailing-List: linux-erofs@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260625174758.GE6078@frogsfrogsfrogs> User-Agent: Mutt/1.5.17 (2007-11-01) On Thu, Jun 25, 2026 at 10:47:58AM -0700, Darrick J. Wong wrote: > On Thu, Jun 25, 2026 at 02:07:57PM +0200, Christoph Hellwig wrote: > > Currently the iomap buffered read path tries to build up read context > > (i.e. bios for the typical block based case) over multiple iomaps as > > long as the sector matches. This does not take into account files > > that can map to multiple different devices. While this could be fixed > > by a bdev check in iomap_bio_read_folio_range, the building up of I/O > > over iomaps actually was a problem for the not yet merged ext2 iomap > > port, as that does want to send out I/O at the end of an indirect > > block mapped range. > > This really puts the onus on block-mapped filesystems (e.g. ext2) to > merge adjacent maps into extents. Granted they *probably* already have > been doing that. Yes. In fact the ext2 conversion was the first ask for this change, because they do not want unlimited merging but kick off I/O at the indirect block boundary. > > So instead of adding more checks move over to a model where a bio only > > spans a single iomap. Change ->submit_read to be called after each > > iteration, and pass a force argument to indicate that the bio must > > be submitted set on the last iteration. Switch the bio based users > > to always submit, while keeping the single submit for fuse. > > Is fuse the sole reason for the "force" parameter to exist? I wonder if > fuse could drop its submit_read function and call fuse_send_readpages > after the iomap_read{ahead,folio} function returns? Probably..