From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754780Ab3JVTGb (ORCPT ); Tue, 22 Oct 2013 15:06:31 -0400 Received: from static.92.5.9.176.clients.your-server.de ([176.9.5.92]:55650 "EHLO hallynmail2" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753883Ab3JVTG3 (ORCPT ); Tue, 22 Oct 2013 15:06:29 -0400 Date: Tue, 22 Oct 2013 19:06:28 +0000 From: "Serge E. Hallyn" To: "Eric W. Biederman" Cc: Miklos Szeredi , Andy Lutomirski , "Serge E. Hallyn" , Al Viro , Linux-Fsdevel , Kernel Mailing List , Rob Landley , Linus Torvalds , Matthias Schniedermeyer , Linux Containers Subject: Re: [REVIEW][PATCH 2/4] vfs: Keep a list of mounts on a mount point Message-ID: <20131022190628.GB10600@mail.hallyn.com> References: <20131008161135.GK14242@tucsk.piliscsaba.szeredi.hu> <87li23trll.fsf@tw-ebiederman.twitter.com> <87vc15mjuw.fsf@xmission.com> <87iox38fkv.fsf@xmission.com> <87d2nb8dxy.fsf@xmission.com> <87iowyxpci.fsf_-_@xmission.com> <877gdexp9s.fsf_-_@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <877gdexp9s.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 Quoting Eric W. Biederman (ebiederm@xmission.com): > > To spot any possible problems call BUG if a mountpoint > is put when it's list of mounts is not empty. > > Signed-off-by: Eric W. Biederman Acked-by: Serge Hallyn > --- > fs/mount.h | 2 ++ > fs/namespace.c | 6 ++++++ > 2 files changed, 8 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..e4fe22c23e00 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; > } > > @@ -643,6 +645,7 @@ static void put_mountpoint(struct mountpoint *mp) > { > if (!--mp->m_count) { > struct dentry *dentry = mp->m_dentry; > + BUG_ON(!list_empty(&mp->m_list)); > spin_lock(&dentry->d_lock); > dentry->d_flags &= ~DCACHE_MOUNTED; > spin_unlock(&dentry->d_lock); > @@ -689,6 +692,7 @@ static void detach_mnt(struct mount *mnt, struct path *old_path) > mnt->mnt_mountpoint = mnt->mnt.mnt_root; > list_del_init(&mnt->mnt_child); > list_del_init(&mnt->mnt_hash); > + list_del_init(&mnt->mnt_mp_list); > put_mountpoint(mnt->mnt_mp); > mnt->mnt_mp = NULL; > } > @@ -705,6 +709,7 @@ 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); > } > > /* > @@ -1191,6 +1196,7 @@ void umount_tree(struct mount *mnt, int propagate) > list_del_init(&p->mnt_child); > if (mnt_has_parent(p)) { > p->mnt_parent->mnt_ghosts++; > + list_del_init(&p->mnt_mp_list); > put_mountpoint(p->mnt_mp); > p->mnt_mp = NULL; > } > -- > 1.7.5.4