From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 1BB2822837F; Tue, 10 Jun 2025 03:49:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749527367; cv=none; b=IMndreVZkiJp1w0BclEMeqmdiFy4HqGilIHtthCxT1P/IzkQdFrrqdXKhoJI6tKqWkY1vvRLQ938NYwM7ZRMk0Y1XhEuQU17+qNQ69yB7PKPnpUxW9ziaupMK8pb7QQ10ujF6WIVv9rDqxfLe5zJbxqu1zGmkIVFYwGaX2p/jOQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749527367; c=relaxed/simple; bh=96gf3+9RfeP1SR68eJdyHt3SeP3bW1j6v7cQwo2RfX0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=CXNPw76Zj2mmFqbGrCe8iWTe7SNu3bH9YTmqPHQzKkcnTsun8L9pdCpX34EAHwUkx6nE1aViMOpRGqPQt2ODcDBtSnYj6uHZIeBJSmJmOkMsi1GrnY6J3KwEYNjIOJZqb0VFR8rytC9LIq4YVP98UbNvRazpm0a7evJjeVoPCfY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=G2+6OHpm; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="G2+6OHpm" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; 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; bh=uBRuHciQtVNLJM1VRmIo0ajCcX2iRkczdJU3q9Eyj/o=; b=G2+6OHpm1c0hYazxJAvTYikA1x aPUVyDDmhmuyge/3iK0mVGpa6L8vv8R8yzknxRMAcpR9df6Y0bJKPwJrNqAMXXDLyxQ5fNGBxTaUU gH5HMy3j8sgmH6Yb5wEiHLr4+UcS9rdFeSIXlGuAfv2N+/obxek6S1MYqezR3bDppRHV/rNj9ONKw L5fYcWswEz2v6UNpdyq29WPrE4pSxQJGx2vgbVov0E2WkTdLojuA40pMOahHJYThlStFzsp4n5gcs 3gaii/Yvz5D89iv5LICWfdF/XrProbVEJjck62WhN4/iJOVrA03WCkD4kzzr4BUMJwFph2WSfKdkK uhP8bH1w==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uOpzJ-00000005i0r-1ocY; Tue, 10 Jun 2025 03:49:25 +0000 Date: Mon, 9 Jun 2025 20:49:25 -0700 From: Christoph Hellwig To: "Darrick J. Wong" Cc: Christoph Hellwig , 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: 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: <20250609165741.GK6156@frogsfrogsfrogs> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html 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? > 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.