get rid of useless vfsmount_lock use in put_mnt_ns()

It hadn't been needed since we'd sanitized the logics in
mark_mounts_for_expiry() (which, in turn, used to be a
rudiment of bad old times when namespace_sem was per-ns).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namespace.c b/fs/namespace.c
index 970fe79..b0b15cc 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2344,17 +2344,13 @@ void __init mnt_init(void)
 
 void put_mnt_ns(struct mnt_namespace *ns)
 {
-       struct vfsmount *root;
        LIST_HEAD(umount_list);
 
-       if (!atomic_dec_and_lock(&ns->count, &vfsmount_lock))
+       if (!atomic_dec_and_test(&ns->count))
                return;
-       root = ns->root;
-       ns->root = NULL;
-       spin_unlock(&vfsmount_lock);
        down_write(&namespace_sem);
        spin_lock(&vfsmount_lock);
-       umount_tree(root, 0, &umount_list);
+       umount_tree(ns->root, 0, &umount_list);
        spin_unlock(&vfsmount_lock);
        up_write(&namespace_sem);
        release_mounts(&umount_list);