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>

1 files changed, 2 insertions, 6 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 970fe79d7867..b0b15cc2117c 100644
--- 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);