1 files changed, 33 insertions, 9 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index c7cb8a526c05..2b8aa15fd6df 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1361,6 +1361,36 @@ enum umount_tree_flags {
         UMOUNT_PROPAGATE = 2,
         UMOUNT_CONNECTED = 4,
 };
+
+static bool disconnect_mount(struct mount *mnt, enum umount_tree_flags how)
+{
+        /* Leaving mounts connected is only valid for lazy umounts */
+        if (how & UMOUNT_SYNC)
+                return true;
+
+        /* A mount without a parent has nothing to be connected to */
+        if (!mnt_has_parent(mnt))
+                return true;
+
+        /* Because the reference counting rules change when mounts are
+         * unmounted and connected, umounted mounts may not be
+         * connected to mounted mounts.
+         */
+        if (!(mnt->mnt_parent->mnt.mnt_flags & MNT_UMOUNT))
+                return true;
+
+        /* Has it been requested that the mount remain connected? */
+        if (how & UMOUNT_CONNECTED)
+                return false;
+
+        /* Is the mount locked such that it needs to remain connected? */
+        if (IS_MNT_LOCKED(mnt))
+                return false;
+
+        /* By default disconnect the mount */
+        return true;
+}
+
 /*
  * mount_lock must be held
  * namespace_sem must be held for write
@@ -1398,10 +1428,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
                 if (how & UMOUNT_SYNC)
                         p->mnt.mnt_flags |= MNT_SYNC_UMOUNT;
 
-                disconnect = !(((how & UMOUNT_CONNECTED) &&
-                                mnt_has_parent(p) &&
-                                (p->mnt_parent->mnt.mnt_flags & MNT_UMOUNT)) ||
-                               IS_MNT_LOCKED_AND_LAZY(p));
+                disconnect = disconnect_mount(p, how);
 
                 pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt,
                                  disconnect ? &unmounted : NULL);
@@ -1538,11 +1565,8 @@ void __detach_mounts(struct dentry *dentry)
         while (!hlist_empty(&mp->m_list)) {
                 mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);
                 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);
-                        }
+                        hlist_add_head(&mnt->mnt_umount.s_list, &unmounted);
+                        umount_mnt(mnt);
                 }
                 else umount_tree(mnt, UMOUNT_CONNECTED);
         }