From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=213.95.11.211 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794409012; b=lBIJqOfVroz66XqZMACwnq77wFnnibNZ9d6xCCqANCKLR8L+z+uR/cIKCcnEhiTiyTRC iol0jq1B3h6zZ9BAswMEr0+Gi/YpG+rDVLnRDitVv8pUV/DFJkM+2zSgLxywBDLSXoURJ HkRbhy90QMaf1Nxl6Wo7MpYFnTORH6PoRi1aC7sKFMY6MEhUYdQcDOxa7m+gmqi6Hg0Ew ptpuD9uQdyL4hl/H+zeQxt+PoIKYujw23qB/mAHpNt8TP0RltncoYCZ/bXmMN0MyqeRcn Pf3PizwXQkjjkM6VHPzd0XlDmS/hgS3efl+4VgsPx3rkBHAAJXiaHRtmviJtKQwMJDA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794409012; h=DMARC-Filter:Received:Date:From:To:Cc:Subject:Message-ID:References: MIME-Version:Content-Type:Content-Disposition:In-Reply-To:User-Agent; bh=uTScRtTvc50Ly2VnPZ+IRL7zVmHRGtRnjIEMUslXOU4=; b=Qobh15CJ3JpoTdqtIsJPaZ4wbdspYIDAKZ8haFc3oVC5+YRq8uyZXzAw7VqpXVYavruy BZvIuh31v+f5Xm69m9HpVd6exHSKnu5D7WixXZS7CYYjd9MGVYxRTgyV28vghBPGWvjX2 8axfaQRopt9gI24sSklTdzPNqedWv3dV3uU+7+Lyk9cKh50z2KgzSLoz6zj0LwhMWcbzG v01GEbalvED5ZoYPi3+OyJq6qwblxWqKxR6weT9IYbMeulfkLaBNKH7A34rIJCaMiFfFr ZrXjxjMlOI719XN0ejuOimrm2yCAnSLtFkqufP++Fd2ZGpVH6b3SlI3pqN+bGkjwX5Q== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=lst.de; spf=pass smtp.mailfrom=lst.de; arc=none smtp.remote-ip=213.95.11.211 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 824FE606A331; Wed, 11 Nov 2026 14:56:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 824FE606A331 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lst.de Received: by verein.lst.de (Postfix, from userid 2407) id BF2AF68D09; Wed, 11 Nov 2026 15:56:47 +0100 (CET) Date: Wed, 11 Nov 2026 15:56:47 +0100 From: Christoph Hellwig To: Christian Brauner Cc: linux-fsdevel@vger.kernel.org, Jann Horn , Chris Mason , Josef Bacik , Christoph Hellwig , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Alexander Viro , Jan Kara , linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, driver-core@lists.linux.dev, linux-mm@kvack.org, bpf@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, apparmor@lists.ubuntu.com, linux-nfs@vger.kernel.org, netdev@vger.kernel.org, fuse-devel@lists.linux.dev, linux-efi@vger.kernel.org, xen-devel@lists.xenproject.org, ocfs2-devel@lists.linux.dev, linux-s390@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-usb@vger.kernel.org, Amir Goldstein , linux-erofs@lists.ozlabs.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC 03/41] target: fileio: check that the backing file supports ->{read,write}_iter Message-ID: <20261111145647.GC9996@lst.de> References: <20261110-work-loop-pseudo-v1-0-4c998976c6c7@kernel.org> <20261110-work-loop-pseudo-v1-3-4c998976c6c7@kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261110-work-loop-pseudo-v1-3-4c998976c6c7@kernel.org> User-Agent: Mutt/1.5.17 (2007-11-01) On Tue, Nov 10, 2026 at 10:14:19AM +0100, Christian Brauner wrote: > With fd_async_io=1 the fileio backend calls ->read_iter() and > ->write_iter() of the backing file directly. The synchronous path goes > through vfs_iter_read() and vfs_iter_write() which check for them but > the aio path doesn't. So a backing file without them calls a NULL > pointer on its first I/O. > > Refuse such files when configuring the device. On the synchronous path > every read or write that needed the missing method failed with EINVAL > anyway. Looks good: Reviewed-by: Christoph Hellwig