Hi Aleksa,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[cannot apply to v5.4-rc1 next-20190930]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Aleksa-Sarai/namei-openat2-2-path-resolution-restrictions/20191001-025628
config: x86_64-randconfig-s0-201939 (attached as .config)
compiler: gcc-5 (Ubuntu 5.5.0-12ubuntu1) 5.5.0 20171010
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   fs/open.c: In function '__do_sys_openat2':
>> fs/open.c:1173:8: error: implicit declaration of function 'copy_struct_from_user' [-Werror=implicit-function-declaration]
     err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
           ^
   cc1: some warnings being treated as errors

vim +/copy_struct_from_user +1173 fs/open.c

  1163	
  1164	SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
  1165			const struct open_how __user *, how, size_t, usize)
  1166	{
  1167		int err;
  1168		struct open_how tmp;
  1169	
  1170		if (unlikely(usize < OPEN_HOW_SIZE_VER0))
  1171			return -EINVAL;
  1172	
> 1173		err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
  1174		if (err)
  1175			return err;
  1176	
  1177		if (force_o_largefile())
  1178			tmp.flags |= O_LARGEFILE;
  1179	
  1180		return do_sys_open(dfd, filename, &tmp);
  1181	}
  1182	

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0-DAY kernel test infrastructure                Open Source Technology Center
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