Hi Naohiro, Thank you for the patch! Yet something to improve: [auto build test ERROR on linus/master] [cannot apply to v5.3-rc5 next-20190823] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Naohiro-Aota/btrfs-zoned-block-device-support/20190824-160033 config: i386-randconfig-a004-201934 (attached as .config) compiler: gcc-6 (Debian 6.3.0-18+deb9u1) 6.3.0 20170516 reproduce: # save the attached .config to linux build tree make ARCH=i386 If you fix the issue, kindly add following tag Reported-by: kbuild test robot All errors (new ones prefixed by >>): fs/btrfs/hmzoned.c: In function 'btrfs_get_dev_zones': fs/btrfs/hmzoned.c:31:8: error: implicit declaration of function 'blkdev_report_zones' [-Werror=implicit-function-declaration] ret = blkdev_report_zones(device->bdev, pos >> SECTOR_SHIFT, ^~~~~~~~~~~~~~~~~~~ fs/btrfs/hmzoned.c: In function 'btrfs_reset_device_zone': >> fs/btrfs/hmzoned.c:602:8: error: implicit declaration of function 'blkdev_reset_zones' [-Werror=implicit-function-declaration] ret = blkdev_reset_zones(device->bdev, ^~~~~~~~~~~~~~~~~~ cc1: some warnings being treated as errors vim +/blkdev_reset_zones +602 fs/btrfs/hmzoned.c 596 597 int btrfs_reset_device_zone(struct btrfs_device *device, u64 physical, 598 u64 length, u64 *bytes) 599 { 600 int ret; 601 > 602 ret = blkdev_reset_zones(device->bdev, --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation