Hi "Matthew,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on next-20210715]
[cannot apply to hnaz-linux-mm/master xfs-linux/for-next tip/perf/core v5.14-rc1]
[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: arm-randconfig-r014-20210715 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 0e49c54a8cbd3e779e5526a5888c683c01cc3c50)
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 arm cross compiling tool for clang build
        # apt-get install binutils-arm-linux-gnueabi
        # https://github.com/0day-ci/linux/commit/fd265884da3f65758e8b5153d45537a4bbefbb70
        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 fd265884da3f65758e8b5153d45537a4bbefbb70
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm 

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/iomap/buffered-io.c:645:2: error: implicit declaration of function 'flush_dcache_folio' [-Werror,-Wimplicit-function-declaration]
           flush_dcache_folio(folio);
           ^
   fs/iomap/buffered-io.c:645:2: note: did you mean 'flush_dcache_page'?
   arch/arm/include/asm/cacheflush.h:292:13: note: 'flush_dcache_page' declared here
   extern void flush_dcache_page(struct page *);
               ^
   1 error generated.


vim +/flush_dcache_folio +645 fs/iomap/buffered-io.c

   640	
   641	static size_t __iomap_write_end(struct inode *inode, loff_t pos, size_t len,
   642			size_t copied, struct folio *folio)
   643	{
   644		struct iomap_page *iop = to_iomap_page(folio);
 > 645		flush_dcache_folio(folio);
   646	
   647		/*
   648		 * The blocks that were entirely written will now be uptodate, so we
   649		 * don't have to worry about a readpage reading them and overwriting a
   650		 * partial write.  However if we have encountered a short write and only
   651		 * partially written into a block, it will not be marked uptodate, so a
   652		 * readpage might come in and destroy our partial write.
   653		 *
   654		 * Do the simplest thing, and just treat any short write to a non
   655		 * uptodate page as a zero-length write, and force the caller to redo
   656		 * the whole thing.
   657		 */
   658		if (unlikely(copied < len && !folio_test_uptodate(folio)))
   659			return 0;
   660		iomap_set_range_uptodate(folio, iop, offset_in_folio(folio, pos), len);
   661		filemap_dirty_folio(inode->i_mapping, folio);
   662		return copied;
   663	}
   664	

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