3 files changed, 32 insertions, 5 deletions

diff --git a/fs/mount.h b/fs/mount.h
index bf1fda6eed8f..ede5a1d5cf99 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -58,6 +58,7 @@ struct mount {
         struct mnt_namespace *mnt_ns;   /* containing namespace */
         struct mountpoint *mnt_mp;      /* where is it mounted */
         struct hlist_node mnt_mp_list;  /* list mounts with the same mountpoint */
+        struct list_head mnt_reparent;  /* reparent list entry */
 #ifdef CONFIG_FSNOTIFY
         struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks;
         __u32 mnt_fsnotify_mask;
diff --git a/fs/namespace.c b/fs/namespace.c
index 8bd3e4d448b9..51e49866e1fe 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -236,6 +236,7 @@ static struct mount *alloc_vfsmnt(const char *name)
                 INIT_LIST_HEAD(&mnt->mnt_slave_list);
                 INIT_LIST_HEAD(&mnt->mnt_slave);
                 INIT_HLIST_NODE(&mnt->mnt_mp_list);
+                INIT_LIST_HEAD(&mnt->mnt_reparent);
                 init_fs_pin(&mnt->mnt_umount, drop_mountpoint);
         }
         return mnt;
diff --git a/fs/pnode.c b/fs/pnode.c
index 5bc7896d122a..52aca0a118ff 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -439,7 +439,7 @@ static void mark_umount_candidates(struct mount *mnt)
  * NOTE: unmounting 'mnt' naturally propagates to all other mounts its
  * parent propagates to.
  */
-static void __propagate_umount(struct mount *mnt)
+static void __propagate_umount(struct mount *mnt, struct list_head *to_reparent)
 {
         struct mount *parent = mnt->mnt_parent;
         struct mount *m;
@@ -464,17 +464,38 @@ static void __propagate_umount(struct mount *mnt)
                  */
                 topper = find_topper(child);
                 if (topper)
-                        mnt_change_mountpoint(child->mnt_parent, child->mnt_mp,
-                                              topper);
+                        list_add_tail(&topper->mnt_reparent, to_reparent);
 
-                if (list_empty(&child->mnt_mounts)) {
+                if (topper || list_empty(&child->mnt_mounts)) {
                         list_del_init(&child->mnt_child);
+                        list_del_init(&child->mnt_reparent);
                         child->mnt.mnt_flags |= MNT_UMOUNT;
                         list_move_tail(&child->mnt_list, &mnt->mnt_list);
                 }
         }
 }
 
+static void reparent_mounts(struct list_head *to_reparent)
+{
+        while (!list_empty(to_reparent)) {
+                struct mount *mnt, *parent;
+                struct mountpoint *mp;
+
+                mnt = list_first_entry(to_reparent, struct mount, mnt_reparent);
+                list_del_init(&mnt->mnt_reparent);
+
+                /* Where should this mount be reparented to? */
+                mp = mnt->mnt_mp;
+                parent = mnt->mnt_parent;
+                while (parent->mnt.mnt_flags & MNT_UMOUNT) {
+                        mp = parent->mnt_mp;
+                        parent = parent->mnt_parent;
+                }
+
+                mnt_change_mountpoint(parent, mp, mnt);
+        }
+}
+
 /*
  * collect all mounts that receive propagation from the mount in @list,
  * and return these additional mounts in the same list.
@@ -485,11 +506,15 @@ static void __propagate_umount(struct mount *mnt)
 int propagate_umount(struct list_head *list)
 {
         struct mount *mnt;
+        LIST_HEAD(to_reparent);
 
         list_for_each_entry_reverse(mnt, list, mnt_list)
                 mark_umount_candidates(mnt);
 
         list_for_each_entry(mnt, list, mnt_list)
-                __propagate_umount(mnt);
+                __propagate_umount(mnt, &to_reparent);
+
+        reparent_mounts(&to_reparent);
+
         return 0;
 }