From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754781Ab3JHNoO (ORCPT ); Tue, 8 Oct 2013 09:44:14 -0400 Received: from mail-ee0-f49.google.com ([74.125.83.49]:38504 "EHLO mail-ee0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753273Ab3JHNoH (ORCPT ); Tue, 8 Oct 2013 09:44:07 -0400 Date: Tue, 8 Oct 2013 15:44:53 +0200 From: Miklos Szeredi To: "Eric W. Biederman" Cc: "Serge E. Hallyn" , Al Viro , Linux-Fsdevel , Kernel Mailing List , Andy Lutomirski , Rob Landley , Linus Torvalds Subject: Re: [RFC][PATCH 1/3] vfs: Keep a list of mounts on a mount point Message-ID: <20131008134453.GG14242@tucsk.piliscsaba.szeredi.hu> References: <87a9kkax0j.fsf@xmission.com> <8761v7h2pt.fsf@tw-ebiederman.twitter.com> <87li281wx6.fsf_-_@xmission.com> <87fvsg1wv6.fsf_-_@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87fvsg1wv6.fsf_-_@xmission.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 04, 2013 at 03:42:37PM -0700, Eric W. Biederman wrote: > > Signed-off-by: Eric W. Biederman > --- > fs/mount.h | 2 ++ > fs/namespace.c | 5 +++++ > 2 files changed, 7 insertions(+), 0 deletions(-) > > diff --git a/fs/mount.h b/fs/mount.h > index 64a858143ff9..e4342b8dfab1 100644 > --- a/fs/mount.h > +++ b/fs/mount.h > @@ -21,6 +21,7 @@ struct mnt_pcp { > struct mountpoint { > struct list_head m_hash; > struct dentry *m_dentry; > + struct list_head m_list; > int m_count; > }; > > @@ -47,6 +48,7 @@ struct mount { > struct mount *mnt_master; /* slave is on master->mnt_slave_list */ > struct mnt_namespace *mnt_ns; /* containing namespace */ > struct mountpoint *mnt_mp; /* where is it mounted */ > + struct list_head mnt_mp_list; /* list mounts with the same mountpoint */ > #ifdef CONFIG_FSNOTIFY > struct hlist_head mnt_fsnotify_marks; > __u32 mnt_fsnotify_mask; > diff --git a/fs/namespace.c b/fs/namespace.c > index da5c49483430..d092964fe7f9 100644 > --- a/fs/namespace.c > +++ b/fs/namespace.c > @@ -197,6 +197,7 @@ static struct mount *alloc_vfsmnt(const char *name) > INIT_LIST_HEAD(&mnt->mnt_share); > INIT_LIST_HEAD(&mnt->mnt_slave_list); > INIT_LIST_HEAD(&mnt->mnt_slave); > + INIT_LIST_HEAD(&mnt->mnt_mp_list); > #ifdef CONFIG_FSNOTIFY > INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks); > #endif > @@ -636,6 +637,7 @@ static struct mountpoint *new_mountpoint(struct dentry *dentry) > mp->m_dentry = dentry; > mp->m_count = 1; > list_add(&mp->m_hash, chain); > + INIT_LIST_HEAD(&mp->m_list); > return mp; > } > > @@ -691,6 +693,7 @@ static void detach_mnt(struct mount *mnt, struct path *old_path) > list_del_init(&mnt->mnt_hash); > put_mountpoint(mnt->mnt_mp); > mnt->mnt_mp = NULL; > + list_del_init(&mnt->mnt_mp_list); Should be done *before* put_mountpoint(), for obvious reasons. And a BUG_ON(!list_empty(&mp->m_list)) in put_mountpoint() for good measure (and no, WARN_ON() is not better here, since use-after-free is definitely worse than a BUG). > } > > /* > @@ -705,6 +708,7 @@ void mnt_set_mountpoint(struct mount *mnt, > child_mnt->mnt_mountpoint = dget(mp->m_dentry); > child_mnt->mnt_parent = mnt; > child_mnt->mnt_mp = mp; > + list_add_tail(&child_mnt->mnt_mp_list, &mp->m_list); > } > > /* > @@ -1193,6 +1197,7 @@ void umount_tree(struct mount *mnt, int propagate) > p->mnt_parent->mnt_ghosts++; > put_mountpoint(p->mnt_mp); > p->mnt_mp = NULL; > + list_del_init(&mnt->mnt_mp_list); Ditto. > } > change_mnt_propagation(p, MS_PRIVATE); > } > -- > 1.7.5.4 >