From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-99.freemail.mail.aliyun.com (out30-99.freemail.mail.aliyun.com [115.124.30.99]) (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 55B633FB075 for ; Wed, 17 Jun 2026 14:23:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.99 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781706218; cv=none; b=ng/TG9f8sZ6L7k5A6IZgetPumahWHc9eXaw4etp4mBGSCX86jWhSA/up88pOTROiUxeZIZ08a9fq/7X9Qe0KsxClst/EOsAZDTyQ3TefEaUDhFrZKnUwAO2j6dv3DrH5TwK9hF0ZCLKdGh5fZn1LWctL8ctKNpokMfrBfodkBeo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781706218; c=relaxed/simple; bh=4OrGCeLcSDfOcDzbTmyuu4uMLYeihA5aKajB96CfwYE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TboFlN89TLqWE3KeQr6el/fKXd0uEQ+n4CsleUU2/b524+fBliOwBSGn9EebZYH32ryvCOWFCxKUvYzQIzravPNKy8bbaPyri6X6E6Ck8QtYPo1Dlk9RtSDmgCRPnC4oZW9JF9L8/gRZyfdJOVw/K0s/pJTLUs4kEWO6fjXvuWo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=v7yESB7j; arc=none smtp.client-ip=115.124.30.99 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="v7yESB7j" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1781706204; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=vhvsUEgLYTUDkOIBA4DwsqfV7AptAA3xKwJAvS7jSGY=; b=v7yESB7jJfP8wWAU5lV7CgGxKa+WQqNXLb4DW8e8J0BnCTaqcLLCTP3ZYRIK98c/1MLSZ5ZsGbwR1g0K8WNVBBwtCyEJi33xSbeTD/zvpCogO+KwUptZuAcCtw9BCnWch1iIJw3tkzuEOREesozVqLcg/6aL9HV5QJhclx5MTk4= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R611e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037026112;MF=hsiangkao@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0X53odUx_1781706202; Received: from 30.120.66.214(mailfrom:hsiangkao@linux.alibaba.com fp:SMTPD_---0X53odUx_1781706202 cluster:ay36) by smtp.aliyun-inc.com; Wed, 17 Jun 2026 22:23:23 +0800 Message-ID: <905b7d03-3e35-4db5-b72e-51051b034cf4@linux.alibaba.com> Date: Wed, 17 Jun 2026 22:23:22 +0800 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Stacking filesystem deadlocks [was Re: Fanotify (hsm or erofs) / fuse / nbd / ... + write(mmap) deadlock vector followup] To: Christian Brauner , Amir Goldstein Cc: Jan Kara , "linux-fsdevel@vger.kernel.org" , Miklos Szeredi , Gao Xiang , Song Liu References: <95371379-97e9-4cb4-8358-ec014b765b74@linux.alibaba.com> <5lz5jq7gzoejbywmh56ayfkdiuqsjd2s5pl5uvlflfxc5lq4rr@thr4hrkw67d2> <64f23c85-2a83-42e4-ba09-c815dcb7c98c@linux.alibaba.com> <20260617-vorfahren-haften-nullnummer-b0d6fccadae3@brauner> From: Gao Xiang In-Reply-To: <20260617-vorfahren-haften-nullnummer-b0d6fccadae3@brauner> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2026/6/17 21:37, Christian Brauner wrote: > On Thu, Jun 11, 2026 at 05:25:56PM +0200, Amir Goldstein wrote: >> On Thu, Jun 11, 2026 at 1:32 PM Jan Kara wrote: ... >> >> My crystal ball tells me we are probably not going to do that :-/ >> But if we did, it would have been nice to validate that LOOP_CHANGE_FD >> does not set the backing file of loopA to a file on fsB ;) > > LOOP_CHANGE_FD should be removed. I proposed that years ago because it's > problematic in other ways. Everyone agreed as it was effectively unused > I just never bothered pushing it through. So let's not worry about that > let's kill it instead. Here's the patch from 2023: > > From 46db77d781d329b7fc7b3245dd295a69026f6ec0 Mon Sep 17 00:00:00 2001 > From: Christian Brauner > Date: Mon, 6 Nov 2023 16:29:32 +0100 > Subject: [PATCH] loop: remove support for swapping loop fds > > We did not find any users of LOOP_CHANGE_FD. > > Signed-off-by: Christian Brauner I am glad if it could be dropped so at least I will not worry about missing features if fs shutdown is implemented in erofs. Thanks, Gao Xiang