Hi Qu,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on kdave/for-next]
[also build test ERROR on next-20201210]
[cannot apply to v5.10-rc7]
[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/Qu-Wenruo/btrfs-add-read-only-support-for-subpage-sector-size/20201210-144442
base:   https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next
config: i386-randconfig-a013-20201209 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/e01cdf51d0d32647697616c0dd08f2cc3220bde4
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Qu-Wenruo/btrfs-add-read-only-support-for-subpage-sector-size/20201210-144442
        git checkout e01cdf51d0d32647697616c0dd08f2cc3220bde4
        # save the attached .config to linux build tree
        make W=1 ARCH=i386 

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 >>):

   ld: fs/btrfs/disk-io.o: in function `validate_subpage_buffer':
>> fs/btrfs/disk-io.c:619: undefined reference to `__udivdi3'

vim +619 fs/btrfs/disk-io.c

   593	
   594	static int validate_subpage_buffer(struct page *page, u64 start, u64 end,
   595					   int mirror)
   596	{
   597		struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb);
   598		struct extent_buffer *eb;
   599		int reads_done;
   600		int ret = 0;
   601	
   602		if (!IS_ALIGNED(start, fs_info->sectorsize) ||
   603		    !IS_ALIGNED(end - start + 1, fs_info->sectorsize) ||
   604		    !IS_ALIGNED(end - start + 1, fs_info->nodesize)) {
   605			WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
   606			btrfs_err(fs_info, "invalid tree read bytenr");
   607			return -EUCLEAN;
   608		}
   609	
   610		/*
   611		 * We don't allow bio merge for subpage metadata read, so we should
   612		 * only get one eb for each endio hook.
   613		 */
   614		ASSERT(end == start + fs_info->nodesize - 1);
   615		ASSERT(PagePrivate(page));
   616	
   617		rcu_read_lock();
   618		eb = radix_tree_lookup(&fs_info->buffer_radix,
 > 619				       start / fs_info->sectorsize);
   620		rcu_read_unlock();
   621	
   622		/*
   623		 * When we are reading one tree block, eb must have been
   624		 * inserted into the radix tree. If not something is wrong.
   625		 */
   626		if (!eb) {
   627			WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
   628			btrfs_err(fs_info,
   629				"can't find extent buffer for bytenr %llu",
   630				start);
   631			return -EUCLEAN;
   632		}
   633		/*
   634		 * The pending IO might have been the only thing that kept
   635		 * this buffer in memory.  Make sure we have a ref for all
   636		 * this other checks
   637		 */
   638		atomic_inc(&eb->refs);
   639	
   640		reads_done = atomic_dec_and_test(&eb->io_pages);
   641		/* Subpage read must finish in page read */
   642		ASSERT(reads_done);
   643	
   644		eb->read_mirror = mirror;
   645		if (test_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags)) {
   646			ret = -EIO;
   647			goto err;
   648		}
   649		ret = validate_extent_buffer(eb);
   650		if (ret < 0)
   651			goto err;
   652	
   653		if (test_and_clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags))
   654			btree_readahead_hook(eb, ret);
   655	
   656		set_extent_buffer_uptodate(eb);
   657	
   658		free_extent_buffer(eb);
   659		return ret;
   660	err:
   661		/*
   662		 * our io error hook is going to dec the io pages
   663		 * again, we have to make sure it has something to
   664		 * decrement
   665		 */
   666		atomic_inc(&eb->io_pages);
   667		clear_extent_buffer_uptodate(eb);
   668		free_extent_buffer(eb);
   669		return ret;
   670	}
   671	

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