1 files changed, 33 insertions, 9 deletions

diff --git a/kernel/fs/namespace.c b/kernel/fs/namespace.c
index c246b29e4..28937028f 100644
--- a/kernel/fs/namespace.c
+++ b/kernel/fs/namespace.c
@@ -1354,6 +1354,36 @@ 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
@@ -1391,10 +1421,7 @@ 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);
@@ -1531,11 +1558,8 @@ 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);
 	}