mnt: Factor out unhash_mnt from detach_mnt and umount_tree

commit 7bdb11de8ee4f4ae195e2fa19efd304e0b36c63b upstream.

Create a function unhash_mnt that contains the common code between
detach_mnt and umount_tree, and use unhash_mnt in place of the common
code.  This add a unncessary list_del_init(mnt->mnt_child) into
umount_tree but given that mnt_child is already empty this extra
line is a noop.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/namespace.c b/fs/namespace.c
index 7d9a69d..0e95c84 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -798,10 +798,8 @@ static void __touch_mnt_namespace(struct mnt_namespace *ns)
 /*
  * vfsmount lock must be held for write
  */
-static void detach_mnt(struct mount *mnt, struct path *old_path)
+static void unhash_mnt(struct mount *mnt)
 {
-       old_path->dentry = mnt->mnt_mountpoint;
-       old_path->mnt = &mnt->mnt_parent->mnt;
        mnt->mnt_parent = mnt;
        mnt->mnt_mountpoint = mnt->mnt.mnt_root;
        list_del_init(&mnt->mnt_child);
@@ -814,6 +812,16 @@ static void detach_mnt(struct mount *mnt, struct path *old_path)
 /*
  * vfsmount lock must be held for write
  */
+static void detach_mnt(struct mount *mnt, struct path *old_path)
+{
+       old_path->dentry = mnt->mnt_mountpoint;
+       old_path->mnt = &mnt->mnt_parent->mnt;
+       unhash_mnt(mnt);
+}
+
+/*
+ * vfsmount lock must be held for write
+ */
 void mnt_set_mountpoint(struct mount *mnt,
                        struct mountpoint *mp,
                        struct mount *child_mnt)
@@ -1364,15 +1372,10 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
 
                pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt, &unmounted);
                if (mnt_has_parent(p)) {
-                       hlist_del_init(&p->mnt_mp_list);
-                       put_mountpoint(p->mnt_mp);
                        mnt_add_count(p->mnt_parent, -1);
                        /* old mountpoint will be dropped when we can do that */
                        p->mnt_ex_mountpoint = p->mnt_mountpoint;
-                       p->mnt_mountpoint = p->mnt.mnt_root;
-                       p->mnt_parent = p;
-                       p->mnt_mp = NULL;
-                       hlist_del_init_rcu(&p->mnt_hash);
+                       unhash_mnt(p);
                }
                change_mnt_propagation(p, MS_PRIVATE);
        }