Hi "Matthew,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v5.14-rc1 next-20210715]
[cannot apply to hnaz-linux-mm/master xfs-linux/for-next tip/perf/core]
[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/Matthew-Wilcox-Oracle/Memory-folios/20210715-133101
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 8096acd7442e613fad0354fc8dfdb2003cceea0b
config: nios2-defconfig (attached as .config)
compiler: nios2-linux-gcc (GCC) 10.3.0
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
        # https://github.com/0day-ci/linux/commit/8e4044529261dffc386ab56b6d90e8511c820605
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Matthew-Wilcox-Oracle/Memory-folios/20210715-133101
        git checkout 8e4044529261dffc386ab56b6d90e8511c820605
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.3.0 make.cross ARCH=nios2 

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 >>):

   In file included from include/linux/fscache.h:22,
                    from fs/nfs/fscache.h:14,
                    from fs/nfs/client.c:48:
   include/linux/netfs.h: In function 'folio_start_fscache':
>> include/linux/netfs.h:43:2: error: implicit declaration of function 'folio_set_private_2_flag'; did you mean 'folio_set_private_2'? [-Werror=implicit-function-declaration]
      43 |  folio_set_private_2_flag(folio);
         |  ^~~~~~~~~~~~~~~~~~~~~~~~
         |  folio_set_private_2
   cc1: some warnings being treated as errors


vim +43 include/linux/netfs.h

    31	
    32	/**
    33	 * folio_start_fscache - Start an fscache write on a folio.
    34	 * @folio: The folio.
    35	 *
    36	 * Call this function before writing a folio to a local cache.  Starting a
    37	 * second write before the first one finishes is not allowed.
    38	 */
    39	static inline void folio_start_fscache(struct folio *folio)
    40	{
    41		VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio);
    42		folio_get(folio);
  > 43		folio_set_private_2_flag(folio);
    44	}
    45	

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