Hi Chao,

I love your patch! Yet something to improve:

[auto build test ERROR on f2fs/dev-test]
[cannot apply to v5.10-rc6 next-20201201]
[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/Chao-Yu/f2fs-compress-support-compress-level/20201202-230008
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git dev-test
config: i386-randconfig-a013-20201202 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/d9c3b7b5530238923fb521561c309a98b1e3797a
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Chao-Yu/f2fs-compress-support-compress-level/20201202-230008
        git checkout d9c3b7b5530238923fb521561c309a98b1e3797a
        # 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 errors (new ones prefixed by >>):

   ld: fs/f2fs/super.o: in function `f2fs_compress_set_level':
>> fs/f2fs/super.c:505: undefined reference to `ZSTD_maxCLevel'

vim +505 fs/f2fs/super.c

   468	
   469	#ifdef CONFIG_F2FS_FS_COMPRESSION
   470	static int f2fs_compress_set_level(struct f2fs_sb_info *sbi, const char *str,
   471							int type)
   472	{
   473		unsigned int level;
   474		int len;
   475	
   476		if (type == COMPRESS_LZ4)
   477			len = 3;
   478		else if (type == COMPRESS_ZSTD)
   479			len = 4;
   480		else
   481			return 0;
   482	
   483		if (strlen(str) == len)
   484			return 0;
   485	
   486		str += len;
   487	
   488		if (str[0] != ':') {
   489			f2fs_info(sbi, "wrong format, e.g. <alg_name>:<compr_level>");
   490			return -EINVAL;
   491		}
   492		if (kstrtouint(str + 1, 10, &level))
   493			return -EINVAL;
   494		if (type == COMPRESS_LZ4) {
   495	#ifdef CONFIG_F2FS_FS_LZ4HC
   496			if (level < LZ4HC_MIN_CLEVEL || level > LZ4HC_MAX_CLEVEL) {
   497				f2fs_info(sbi, "invalid lz4hc compress level: %d", level);
   498				return -EINVAL;
   499			}
   500	#else
   501			f2fs_info(sbi, "doesn't support lz4hc compression");
   502			return 0;
   503	#endif
   504		} else if (type == COMPRESS_ZSTD) {
 > 505			if (!level || level > ZSTD_maxCLevel()) {
   506				f2fs_info(sbi, "invalid zstd compress level: %d", level);
   507				return -EINVAL;
   508			}
   509		}
   510		F2FS_OPTION(sbi).compress_level = level;
   511		return 0;
   512	}
   513	#endif
   514	

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