Re: [PATCH 2/2] btrfs: make btrfs_truncate_block() zero folio range for certain subpage corner cases

[kernel test robot <lkp@intel.com>]

Hi Qu,

kernel test robot noticed the following build warnings:

[auto build test WARNING on kdave/for-next]
[also build test WARNING on linus/master v6.15-rc1 next-20250411]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Qu-Wenruo/btrfs-make-btrfs_truncate_block-to-zero-involved-blocks-in-a-folio/20250411-131525
base:   https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next
patch link:    https://lore.kernel.org/r/d66c922e591b3a57a230ca357b9085fe6ae53812.1744344865.git.wqu%40suse.com
patch subject: [PATCH 2/2] btrfs: make btrfs_truncate_block() zero folio range for certain subpage corner cases
config: arm-randconfig-002-20250412 (https://download.01.org/0day-ci/archive/20250412/202504121224.JBBIEqsn-lkp@intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 7.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250412/202504121224.JBBIEqsn-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202504121224.JBBIEqsn-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from include/linux/kernel.h:27:0,
                    from include/linux/cpumask.h:11,
                    from include/linux/smp.h:13,
                    from include/linux/lockdep.h:14,
                    from include/linux/spinlock.h:63,
                    from include/linux/swait.h:7,
                    from include/linux/completion.h:12,
                    from include/linux/crypto.h:15,
                    from include/crypto/hash.h:12,
                    from fs/btrfs/inode.c:6:
   fs/btrfs/inode.c: In function 'zero_range_folio':
>> include/linux/math.h:15:29: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
    #define __round_mask(x, y) ((__typeof__(x))((y)-1))
                                ^
   include/linux/math.h:35:34: note: in expansion of macro '__round_mask'
    #define round_down(x, y) ((x) & ~__round_mask(x, y))
                                     ^~~~~~~~~~~~
   fs/btrfs/inode.c:4843:16: note: in expansion of macro 'round_down'
     block_start = round_down(clamp_start, block_size);
                   ^~~~~~~~~~
>> include/linux/math.h:15:29: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
    #define __round_mask(x, y) ((__typeof__(x))((y)-1))
                                ^
   include/linux/math.h:25:36: note: in expansion of macro '__round_mask'
    #define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
                                       ^~~~~~~~~~~~
   fs/btrfs/inode.c:4844:14: note: in expansion of macro 'round_up'
     block_end = round_up(clamp_end + 1, block_size) - 1;
                 ^~~~~~~~


vim +15 include/linux/math.h

aa6159ab99a9ab Andy Shevchenko 2020-12-15   8  
aa6159ab99a9ab Andy Shevchenko 2020-12-15   9  /*
aa6159ab99a9ab Andy Shevchenko 2020-12-15  10   * This looks more complex than it should be. But we need to
aa6159ab99a9ab Andy Shevchenko 2020-12-15  11   * get the type for the ~ right in round_down (it needs to be
aa6159ab99a9ab Andy Shevchenko 2020-12-15  12   * as wide as the result!), and we want to evaluate the macro
aa6159ab99a9ab Andy Shevchenko 2020-12-15  13   * arguments just once each.
aa6159ab99a9ab Andy Shevchenko 2020-12-15  14   */
aa6159ab99a9ab Andy Shevchenko 2020-12-15 @15  #define __round_mask(x, y) ((__typeof__(x))((y)-1))
aa6159ab99a9ab Andy Shevchenko 2020-12-15  16  

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