From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: Re: [PATCH review 11/11] mnt: Honor MNT_LOCKED when detaching mounts Date: Wed, 7 Jan 2015 18:43:34 +0000 Message-ID: <20150107184334.GZ22149__35415.6376481571$1420657630$gmane$org@ZenIV.linux.org.uk> References: <87mw5xq7lt.fsf@x220.int.ebiederm.org> <1420490787-14387-11-git-send-email-ebiederm@xmission.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1420490787-14387-11-git-send-email-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: "Eric W. Biederman" Cc: Andrey Vagin , Richard Weinberger , Linux Containers , Andy Lutomirski , linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: containers.vger.kernel.org On Mon, Jan 05, 2015 at 02:46:27PM -0600, Eric W. Biederman wrote: > Modify umount(MNT_DETACH) to keep mounts in the hash table that are > locked to their parent mounts, when the parent is lazily unmounted. > In doing this invert the reference count so that the parent holds a > reference to the children instead of the children holding a reference > to the parent. > > Then in mntput_no_expire detach the children and in cleanup_mnt mntput > the children and dput the dentry they were mounted on. > > In __detach_mounts if there are any mounts that have been unmounted > but still are on the list of mounts of a mountpoint, detach those > mounts and schedule them to be mntput and their reference to the dentry > to be put when it becomes safe to sleep. Explicit description of your new refcounting rules, please. What's more, how do those non-pinning children interact with e.g. copy_tree()?