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: i386-randconfig-m021-20210528 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # 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
        make W=1 ARCH=i386 

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

All error/warnings (new ones prefixed by >>):

   fs/d_path.c: In function 'd_path_fast':
>> fs/d_path.c:302:2: error: implicit declaration of function 'DECLARE_BUFFER' [-Werror=implicit-function-declaration]
     302 |  DECLARE_BUFFER(b, buf, buflen);
         |  ^~~~~~~~~~~~~~
>> fs/d_path.c:302:17: error: 'b' undeclared (first use in this function); did you mean 'mb'?
     302 |  DECLARE_BUFFER(b, buf, buflen);
         |                 ^
         |                 mb
   fs/d_path.c:302:17: note: each undeclared identifier is reported only once for each function it appears in
>> fs/d_path.c:307:14: error: passing argument 2 of 'prepend' from incompatible pointer type [-Werror=incompatible-pointer-types]
     307 |  prepend(&b, "", 1);
         |              ^~
         |              |
         |              char *
   fs/d_path.c:11:40: note: expected 'int *' but argument is of type 'char *'
      11 | static int prepend(char **buffer, int *buflen, const char *str, int namelen)
         |                                   ~~~~~^~~~~~
>> fs/d_path.c:307:18: warning: passing argument 3 of 'prepend' makes pointer from integer without a cast [-Wint-conversion]
     307 |  prepend(&b, "", 1);
         |                  ^
         |                  |
         |                  int
   fs/d_path.c:11:60: note: expected 'const char *' but argument is of type 'int'
      11 | static int prepend(char **buffer, int *buflen, const char *str, int namelen)
         |                                                ~~~~~~~~~~~~^~~
>> fs/d_path.c:307:2: error: too few arguments to function 'prepend'
     307 |  prepend(&b, "", 1);
         |  ^~~~~~~
   fs/d_path.c:11:12: note: declared here
      11 | static int prepend(char **buffer, int *buflen, const char *str, int namelen)
         |            ^~~~~~~
>> fs/d_path.c:308:2: error: implicit declaration of function '__prepend_path'; did you mean 'prepend_path'? [-Werror=implicit-function-declaration]
     308 |  __prepend_path(path->dentry, mnt, &root, &b);
         |  ^~~~~~~~~~~~~~
         |  prepend_path
>> fs/d_path.c:311:9: error: implicit declaration of function 'extract_string'; did you mean 'match_string'? [-Werror=implicit-function-declaration]
     311 |  return extract_string(&b);
         |         ^~~~~~~~~~~~~~
         |         match_string
   fs/d_path.c: At top level:
   fs/d_path.c:336:7: warning: no previous prototype for 'simple_dname' [-Wmissing-prototypes]
     336 | char *simple_dname(struct dentry *dentry, char *buffer, int buflen)
         |       ^~~~~~~~~~~~
   fs/d_path.c: In function 'd_path_fast':
   fs/d_path.c:312:1: error: control reaches end of non-void function [-Werror=return-type]
     312 | }
         | ^
   cc1: some warnings being treated as errors


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
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