SB_I_USERNS_VISIBLE
if (!(s_iflags & SB_I_USERNS_VISIBLE))
s->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC | SB_I_NODEV;
fc->root->d_sb->s_iflags |= SB_I_USERNS_VISIBLE;
if (file_inode(file)->i_sb->s_iflags & SB_I_USERNS_VISIBLE)