Hi David,

I love your patch! Perhaps something to improve:

[auto build test WARNING on kdave/for-next]
[also build test WARNING on next-20210604]
[cannot apply to v5.13-rc4]
[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/David-Sterba/btrfs-sysfs-export-dev-stats-in-devinfo-directory/20210604-212445
base:   https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next
config: arm-randconfig-r004-20210604 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 5c0d1b2f902aa6a9cf47cc7e42c5b83bb2217cf9)
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/8a58ea51305ace4835c7abc51e46b7b64e25b793
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review David-Sterba/btrfs-sysfs-export-dev-stats-in-devinfo-directory/20210604-212445
        git checkout 8a58ea51305ace4835c7abc51e46b7b64e25b793
        # 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 warnings (new ones prefixed by >>):

>> fs/btrfs/sysfs.c:1511:3: warning: format specifies type 'int' but the argument has type 'char *' [-Wformat]
                   "write_errs %d\n"
                   ^~~~~~~~~~~~~~~~~
>> fs/btrfs/sysfs.c:1516:3: warning: data argument not used by format string [-Wformat-extra-args]
                   !!(device->dev_stats_valid),
                   ^
   2 warnings generated.


vim +1511 fs/btrfs/sysfs.c

  1497	
  1498	static ssize_t btrfs_devinfo_stats_show(struct kobject *kobj,
  1499			struct kobj_attribute *a, char *buf)
  1500	{
  1501		struct btrfs_device *device = container_of(kobj, struct btrfs_device,
  1502							   devid_kobj);
  1503	
  1504		/*
  1505		 * Print all at once so we get a snapshot of all values from the same
  1506		 * time. Keep them in sync and in order of definition of
  1507		 * btrfs_dev_stat_values.
  1508		 */
  1509		return scnprintf(buf, PAGE_SIZE,
  1510			"stats_valid %d\n",
> 1511			"write_errs %d\n"
  1512			"read_errs %d\n"
  1513			"flush_errs %d\n"
  1514			"corruption_errs %d\n"
  1515			"generation_errs %d\n",
> 1516			!!(device->dev_stats_valid),
  1517			btrfs_dev_stat_read(device, BTRFS_DEV_STAT_WRITE_ERRS),
  1518			btrfs_dev_stat_read(device, BTRFS_DEV_STAT_READ_ERRS),
  1519			btrfs_dev_stat_read(device, BTRFS_DEV_STAT_FLUSH_ERRS),
  1520			btrfs_dev_stat_read(device, BTRFS_DEV_STAT_CORRUPTION_ERRS),
  1521			btrfs_dev_stat_read(device, BTRFS_DEV_STAT_GENERATION_ERRS));
  1522	}
  1523	BTRFS_ATTR(devid, stats, btrfs_devinfo_stats_show);
  1524	

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