Hi Jia,

[FYI, it's a private test report for your RFC patch.]
[auto build test ERROR on linux/master]
[also build test ERROR on s390/features linus/master v5.13-rc3 next-20210528]
[cannot apply to pmladek/for-next]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Jia-He/make-pD-print-full-path-for-file/20210528-194137
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git dd860052c99b1e088352bdd4fb7aef46f8d2ef47
config: s390-randconfig-r026-20210528 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 6505c630407c5feec818f0bb1c284f9eeebf2071)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install s390 cross compiling tool for clang build
        # apt-get install binutils-s390x-linux-gnu
        # https://github.com/0day-ci/linux/commit/b51dc225479bec60540f41d58a12cf99ff8548d4
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Jia-He/make-pD-print-full-path-for-file/20210528-194137
        git checkout b51dc225479bec60540f41d58a12cf99ff8548d4
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=s390 

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

All errors (new ones prefixed by >>):

>> fs/d_path.c:302:2: error: implicit declaration of function 'DECLARE_BUFFER' [-Werror,-Wimplicit-function-declaration]
           DECLARE_BUFFER(b, buf, buflen);
           ^
>> fs/d_path.c:302:17: error: use of undeclared identifier 'b'
           DECLARE_BUFFER(b, buf, buflen);
                          ^
   fs/d_path.c:307:11: error: use of undeclared identifier 'b'
           prepend(&b, "", 1);
                    ^
>> fs/d_path.c:308:2: error: implicit declaration of function '__prepend_path' [-Werror,-Wimplicit-function-declaration]
           __prepend_path(path->dentry, mnt, &root, &b);
           ^
   fs/d_path.c:308:2: note: did you mean 'prepend_path'?
   fs/d_path.c:75:12: note: 'prepend_path' declared here
   static int prepend_path(const struct path *path,
              ^
   fs/d_path.c:308:44: error: use of undeclared identifier 'b'
           __prepend_path(path->dentry, mnt, &root, &b);
                                                     ^
>> fs/d_path.c:311:9: error: implicit declaration of function 'extract_string' [-Werror,-Wimplicit-function-declaration]
           return extract_string(&b);
                  ^
   fs/d_path.c:311:25: error: use of undeclared identifier 'b'
           return extract_string(&b);
                                  ^
   fs/d_path.c:336:7: warning: no previous prototype for function 'simple_dname' [-Wmissing-prototypes]
   char *simple_dname(struct dentry *dentry, char *buffer, int buflen)
         ^
   fs/d_path.c:336:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   char *simple_dname(struct dentry *dentry, char *buffer, int buflen)
   ^
   static 
   1 warning and 7 errors generated.


vim +/DECLARE_BUFFER +302 fs/d_path.c

   293	
   294	/**
   295	 * d_path_fast - fast return the full path of a dentry without taking
   296	 * any seqlock/spinlock. This helper is typical for debugging purpose
   297	 */
   298	char *d_path_fast(const struct path *path, char *buf, int buflen)
   299	{
   300		struct path root;
   301		struct mount *mnt = real_mount(path->mnt);
 > 302		DECLARE_BUFFER(b, buf, buflen);
   303	
   304		rcu_read_lock();
   305		get_fs_root_rcu(current->fs, &root);
   306	
   307		prepend(&b, "", 1);
 > 308		__prepend_path(path->dentry, mnt, &root, &b);
   309		rcu_read_unlock();
   310	
 > 311		return extract_string(&b);
   312	}
   313	EXPORT_SYMBOL(d_path_fast);
   314	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org