From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [PATCH 12/13] sysfs: Propagate renames to the vfs on demand Date: Sat, 07 Nov 2009 03:57:08 -0800 Message-ID: References: <1257249429-12384-12-git-send-email-ebiederm@xmission.com> <20091104214938.GA21033@us.ibm.com> <4AF4D76C.6090008@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: tj@kernel.org, serue@us.ibm.com, gregkh@suse.de, kay.sievers@vrfy.org, greg@kroah.com, linux-kernel@vger.kernel.org, cornelia.huck@de.ibm.com, linux-fsdevel@vger.kernel.org, eric.dumazet@gmail.com, bcrl@lhnet.ca, ebiederm@aristanetworks.com To: Miklos Szeredi Return-path: Received: from out01.mta.xmission.com ([166.70.13.231]:55966 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751594AbZKGL51 (ORCPT ); Sat, 7 Nov 2009 06:57:27 -0500 In-Reply-To: (Miklos Szeredi's message of "Sat\, 07 Nov 2009 12\:12\:40 +0100") Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Miklos Szeredi writes: > On Fri, 06 Nov 2009, ebiederm@xmission.com (Eric W. Biederman wrote: >> Tejun Heo writes: >> >> > Hello, >> > >> > Eric W. Biederman wrote: >> >> It isn't what I want but it is what the VFS requires. If let the vfs >> >> continue on it's delusional state we will leak the vfs mount and >> >> everything mounted on top of it, with no way to remove the mounts. > > "umount -l" on the whole thing will clear any submounts up too. > >> > >> > This is caused by not having any way to prevent deletion on >> > directories with submounts, right? How does other distributed >> > filesystems deal with directories with submounts going away underneath >> > it? >> >> NFS does exactly the same thing I am doing. > > Yes, this is a problem for NFS too. You cannot tell the NFS server > "this directory is mounted on some client, don't let anything happen > to it!". Basically the remaining choices are: > > a) let the old path leading up to the mount still be accessible, even > though it doesn't exist anymore on the server (or has been replaced > with something different) > > b) automatically dissolve any submounts if the path disappeard on the > server > > I think Al was arguing in favor of b), while Linus said that mounts > must never just disappear, so a) is better. I don't think an > agreement was reached. I haven't seen that conversation. I do know it is non-intutive and if you attempt to delete what is a mount point in another mount namespace and it won't go away. (What we do for non-distributed filesystems). So I would favor mount points dissolving if we had the infrastructure. Regardless the goal for now is to simply catch up with other distributed filesystems. Eric