2 files changed, 9 insertions, 3 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 207c7ba84ad3..4dfcaf05d17c 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -786,7 +786,7 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
         if (!mnt)
                 return ERR_PTR(-ENOMEM);
 
-        if (flag & (CL_SLAVE | CL_PRIVATE))
+        if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE))
                 mnt->mnt_group_id = 0; /* not a peer of original */
         else
                 mnt->mnt_group_id = old->mnt_group_id;
@@ -807,7 +807,8 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
         list_add_tail(&mnt->mnt_instance, &sb->s_mounts);
         br_write_unlock(&vfsmount_lock);
 
-        if (flag & CL_SLAVE) {
+        if ((flag & CL_SLAVE) ||
+            ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) {
                 list_add(&mnt->mnt_slave, &old->mnt_slave_list);
                 mnt->mnt_master = old;
                 CLEAR_MNT_SHARED(mnt);
@@ -2331,6 +2332,7 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
         struct mount *p, *q;
         struct mount *old = mnt_ns->root;
         struct mount *new;
+        int copy_flags;
 
         new_ns = alloc_mnt_ns(user_ns);
         if (IS_ERR(new_ns))
@@ -2338,7 +2340,10 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
 
         down_write(&namespace_sem);
         /* First pass: copy the tree topology */
-        new = copy_tree(old, old->mnt.mnt_root, CL_COPY_ALL | CL_EXPIRE);
+        copy_flags = CL_COPY_ALL | CL_EXPIRE;
+        if (user_ns != mnt_ns->user_ns)
+                copy_flags |= CL_SHARED_TO_SLAVE;
+        new = copy_tree(old, old->mnt.mnt_root, copy_flags);
         if (IS_ERR(new)) {
                 up_write(&namespace_sem);
                 free_mnt_ns(new_ns);
diff --git a/fs/pnode.h b/fs/pnode.h
index 65c60979d541..19b853a3445c 100644
--- a/fs/pnode.h
+++ b/fs/pnode.h
@@ -22,6 +22,7 @@
 #define CL_COPY_ALL             0x04
 #define CL_MAKE_SHARED          0x08
 #define CL_PRIVATE              0x10
+#define CL_SHARED_TO_SLAVE      0x20
 
 static inline void set_mnt_shared(struct mount *mnt)
 {