Do have_submounts(), shrink_dcache_parent() and d_drop() atomically.
check_submounts_and_drop() can deal with negative dentries and
non-directories as well.
Non-directories can also be mounted on.  And just like directories we don't
want these to disappear with invalidation.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
        if (!had_lock)
                gfs2_glock_dq_uninit(&d_gh);
 invalid:
-       if (inode && S_ISDIR(inode->i_mode)) {
-               if (have_submounts(dentry))
-                       goto valid;
-               shrink_dcache_parent(dentry);
-       }
-       d_drop(dentry);
+       if (check_submounts_and_drop(dentry) != 0)
+               goto valid;
+
        dput(parent);
        return 0;