Hi Qu, Thank you for the patch! Yet something to improve: [auto build test ERROR on v5.9-rc5] [also build test ERROR on next-20200915] [cannot apply to kdave/for-next btrfs/next] [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-su... base: 856deb866d16e29bd65952e0289066f6078af773 config: m68k-randconfig-r014-20200913 (attached as .config) compiler: m68k-linux-gcc (GCC) 9.3.0 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 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=m68k If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): m68k-linux-ld: fs/btrfs/disk-io.o: in function `btree_read_subpage_endio_hook': m68k-linux-ld: fs/btrfs/extent_io.o: in function `release_extent_buffer': fs/btrfs/extent_io.c:5480: undefined reference to `__udivdi3' m68k-linux-ld: fs/btrfs/extent_io.o: in function `find_extent_buffer': fs/btrfs/extent_io.c:5230: undefined reference to `__udivdi3' m68k-linux-ld: fs/btrfs/extent_io.o: in function `alloc_extent_buffer': fs/btrfs/extent_io.c:5411: undefined reference to `__udivdi3' # https://github.com/0day-ci/linux/commit/1cc0af35d8945ec5e3a36ca3f0d51c1c7... 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/20200915-133811 git checkout 1cc0af35d8945ec5e3a36ca3f0d51c1c70a37e1a vim +674 fs/btrfs/disk-io.c 647 648 static int btree_read_subpage_endio_hook(struct page *page, u64 start, u64 end, 649 int mirror) 650 { 651 struct btrfs_fs_info *fs_info = page_to_fs_info(page); 652 struct extent_io_tree *io_tree = info_to_btree_io_tree(fs_info); 653 struct extent_buffer *eb; 654 int reads_done; 655 int ret = 0; 656 657 if (!IS_ALIGNED(start, fs_info->sectorsize) || 658 !IS_ALIGNED(end - start + 1, fs_info->sectorsize) || 659 !IS_ALIGNED(end - start + 1, fs_info->nodesize)) { 660 WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)); 661 btrfs_err(fs_info, "invalid tree read bytenr"); 662 return -EUCLEAN; 663 } 664 665 /* 666 * We don't allow bio merge for subpage metadata read, so we should 667 * only get one eb for each endio hook. 668 */ 669 ASSERT(end == start + fs_info->nodesize - 1); 670 ASSERT(PagePrivate(page)); 671 672 rcu_read_lock(); 673 eb = radix_tree_lookup(&fs_info->buffer_radix, 675 rcu_read_unlock(); 676 677 /* 678 * When we are reading one tree block, eb must have been 679 * inserted into the radix tree. If not something is wrong. 680 */ 681 if (!eb) { 682 WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)); 683 btrfs_err(fs_info, 684 "can't find extent buffer for bytenr %llu", 685 start); 686 return -EUCLEAN; 687 } 688 /* 689 * The pending IO might have been the only thing that kept 690 * this buffer in memory. Make sure we have a ref for all 691 * this other checks 692 */ 693 atomic_inc(&eb->refs); 694 695 reads_done = atomic_dec_and_test(&eb->io_pages); 696 /* Subpage read must finish in page read */ 697 ASSERT(reads_done); 698 699 eb->read_mirror= mirror; 700 if (test_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags)) { 701 ret = -EIO; 702 goto err; 703 } 704 ret = btrfs_check_extent_buffer(eb); 705 if (ret < 0) 706 goto err; 707 708 if (test_and_clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags)) 709 btree_readahead_hook(eb, ret); 710 711 set_extent_buffer_uptodate(eb); 712 713 free_extent_buffer(eb); 714 715 /* 716 * Since we don't use PageLocked() but extent_io_tree lock to lock the 717 * range, we need to unlock the range here. 718 */ 719 unlock_extent(io_tree, start, end); 720 return ret; 721 err: 722 /* 723 * our io error hook is going to dec the io pages 724 * again, we have to make sure it has something to 725 * decrement 726 */ 727 atomic_inc(&eb->io_pages); 728 clear_extent_buffer_uptodate(eb); 729 free_extent_buffer(eb); 730 unlock_extent(io_tree, start, end); 731 return ret; 732 } 733 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org