From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman) Subject: [REVIEW][PATCH 2/4] vfs: Keep a list of mounts on a mount point Date: Tue, 15 Oct 2013 13:17:19 -0700 Message-ID: <877gdexp9s.fsf_-_@xmission.com> References: <8761v7h2pt.fsf@tw-ebiederman.twitter.com> <87li281wx6.fsf_-_@xmission.com> <87a9ioo37a.fsf_-_@xmission.com> <20131007043919.GB10284@mail.hallyn.com> <87vc191sf2.fsf@xmission.com> <87d2ngyb02.fsf@xmission.com> <20131008160601.GJ14242@tucsk.piliscsaba.szeredi.hu> <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> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87iowyxpci.fsf_-_-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> (Eric W. Biederman's message of "Tue, 15 Oct 2013 13:15:41 -0700") 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: Miklos Szeredi Cc: Linux Containers , Kernel Mailing List , Andy Lutomirski , Al Viro , Linux-Fsdevel , Matthias Schniedermeyer , Linus Torvalds List-Id: containers.vger.kernel.org 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 --- 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