mnt: Honor MNT_LOCKED when detaching mounts

[cascardo/linux.git] / fs / namespace.c

diff --git a/fs/namespace.c b/fs/namespace.c
index 010d5be..1894d18 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1099,6 +1099,13 @@ static void mntput_no_expire(struct mount *mnt)
        rcu_read_unlock();
 
        list_del(&mnt->mnt_instance);
+
+       if (unlikely(!list_empty(&mnt->mnt_mounts))) {
+               struct mount *p, *tmp;
+               list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts,  mnt_child) {
+                       umount_mnt(p);
+               }
+       }
        unlock_mount_hash();
 
        if (likely(!(mnt->mnt.mnt_flags & MNT_INTERNAL))) {
@@ -1370,6 +1377,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
                propagate_umount(&tmp_list);
 
        while (!list_empty(&tmp_list)) {
+               bool disconnect;
                p = list_first_entry(&tmp_list, struct mount, mnt_list);
                list_del_init(&p->mnt_expire);
                list_del_init(&p->mnt_list);
@@ -1378,10 +1386,18 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
                if (how & UMOUNT_SYNC)
                        p->mnt.mnt_flags |= MNT_SYNC_UMOUNT;
 
-               pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt, &unmounted);
+               disconnect = !IS_MNT_LOCKED_AND_LAZY(p);
+
+               pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt,
+                                disconnect ? &unmounted : NULL);
                if (mnt_has_parent(p)) {
                        mnt_add_count(p->mnt_parent, -1);
-                       umount_mnt(p);
+                       if (!disconnect) {
+                               /* Don't forget about p */
+                               list_add_tail(&p->mnt_child, &p->mnt_parent->mnt_mounts);
+                       } else {
+                               umount_mnt(p);
+                       }
                }
                change_mnt_propagation(p, MS_PRIVATE);
        }
@@ -1506,7 +1522,14 @@ void __detach_mounts(struct dentry *dentry)
        lock_mount_hash();
        while (!hlist_empty(&mp->m_list)) {
                mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);
-               umount_tree(mnt, 0);
+               if (mnt->mnt.mnt_flags & MNT_UMOUNT) {
+                       struct mount *p, *tmp;
+                       list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts,  mnt_child) {
+                               hlist_add_head(&p->mnt_umount.s_list, &unmounted);
+                               umount_mnt(p);
+                       }
+               }
+               else umount_tree(mnt, 0);
        }
        unlock_mount_hash();
        put_mountpoint(mp);