Hi Qu, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on kdave/for-next] [also build test WARNING on v5.9-rc1 next-20200819] [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-switch-btrfs_buf... base: https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next config: arm-randconfig-r022-20200818 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project b34b1e38381fa4d1b1d9751a6b5233b68e734cfe) 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 # 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(a)intel.com&gt; All warnings (new ones prefixed by >>): In file included from fs/btrfs/file.c:19: fs/btrfs/ctree.h:2265:8: warning: 'const' type qualifier on return type has no effect [-Wignored-qualifiers] size_t __const btrfs_get_num_csums(void); ^~~~~~~~ size_t write_bytes = min(iov_iter_count(i), ^~~~~~~~~~~~~~~~~~~~~~ include/linux/kernel.h:884:19: note: expanded from macro 'min' #define min(x, y) __careful_cmp(x, y, <) ^~~~~~~~~~~~~~~~~~~~~~ include/linux/kernel.h:875:24: note: expanded from macro '__careful_cmp' __builtin_choose_expr(__safe_cmp(x, y), \ ^~~~~~~~~~~~~~~~ include/linux/kernel.h:865:4: note: expanded from macro '__safe_cmp' (__typecheck(x, y) && __no_side_effects(x, y)) ^~~~~~~~~~~~~~~~~ include/linux/kernel.h:851:29: note: expanded from macro '__typecheck' (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1))) ~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~ 2 warnings generated. # https://github.com/0day-ci/linux/commit/89f414f96d87eab3a1c3a3afc5283f801... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Qu-Wenruo/btrfs-switch-btrfs_buffered_write-to-page-by-page-pace/20200819-135541 git checkout 89f414f96d87eab3a1c3a3afc5283f80154e7a8b vim +1570 fs/btrfs/file.c 89f414f96d87ea Qu Wenruo 2020-08-19 1550 e4af400a9c5081 Goldwyn Rodrigues 2018-06-17 1551 static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb, e4af400a9c5081 Goldwyn Rodrigues 2018-06-17 1552 struct iov_iter *i) 39279cc3d2704c Chris Mason 2007-06-12 1553 { e4af400a9c5081 Goldwyn Rodrigues 2018-06-17 1554 struct file *file = iocb->ki_filp; e4af400a9c5081 Goldwyn Rodrigues 2018-06-17 1555 loff_t pos = iocb->ki_pos; 496ad9aa8ef448 Al Viro 2013-01-23 1556 struct inode *inode = file_inode(file); 0b246afa62b0cf Jeff Mahoney 2016-06-22 1557 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); 89f414f96d87ea Qu Wenruo 2020-08-19 1558 struct page *page = NULL; 364ecf3651e086 Qu Wenruo 2017-02-27 1559 struct extent_changeset *data_reserved = NULL; 376cc685cb3b43 Miao Xie 2013-12-10 1560 u64 lockstart; 376cc685cb3b43 Miao Xie 2013-12-10 1561 u64 lockend; d0215f3e5ebb58 Josef Bacik 2011-01-25 1562 size_t num_written = 0; c9149235a42ab9 Tsutomu Itoh 2011-03-30 1563 int ret = 0; 7ee9e4405f264e Josef Bacik 2013-06-21 1564 bool only_release_metadata = false; b6316429af7f36 Josef Bacik 2011-09-30 1565 bool force_page_uptodate = false; 4b46fce23349bf Josef Bacik 2010-05-23 1566 d0215f3e5ebb58 Josef Bacik 2011-01-25 1567 while (iov_iter_count(i) > 0) { c67d970f0ea8dc Filipe Manana 2019-09-30 1568 struct extent_state *cached_state = NULL; 7073017aeb98db Johannes Thumshirn 2018-12-05 1569 size_t offset = offset_in_page(pos); d0215f3e5ebb58 Josef Bacik 2011-01-25 @1570 size_t write_bytes = min(iov_iter_count(i), 89f414f96d87ea Qu Wenruo 2020-08-19 1571 PAGE_SIZE - offset); 89f414f96d87ea Qu Wenruo 2020-08-19 1572 size_t reserve_bytes = PAGE_SIZE; d0215f3e5ebb58 Josef Bacik 2011-01-25 1573 size_t copied; 79f015f216539d Goldwyn Rodrigues 2017-10-16 1574 int extents_locked; 39279cc3d2704c Chris Mason 2007-06-12 1575 914ee295af418e Xin Zhong 2010-12-09 1576 /* 89f414f96d87ea Qu Wenruo 2020-08-19 1577 * Fault pages before locking them in prepare_page() 914ee295af418e Xin Zhong 2010-12-09 1578 * to avoid recursive lock 914ee295af418e Xin Zhong 2010-12-09 1579 */ d0215f3e5ebb58 Josef Bacik 2011-01-25 1580 if (unlikely(iov_iter_fault_in_readable(i, write_bytes))) { 914ee295af418e Xin Zhong 2010-12-09 1581 ret = -EFAULT; d0215f3e5ebb58 Josef Bacik 2011-01-25 1582 break; 914ee295af418e Xin Zhong 2010-12-09 1583 } 914ee295af418e Xin Zhong 2010-12-09 1584 a0e248bb502d51 Filipe Manana 2019-10-11 1585 only_release_metadata = false; d9d8b2a51a404c Qu Wenruo 2015-09-08 1586 364ecf3651e086 Qu Wenruo 2017-02-27 1587 extent_changeset_release(data_reserved); 36ea6f3e931391 Nikolay Borisov 2020-06-03 1588 ret = btrfs_check_data_free_space(BTRFS_I(inode), 36ea6f3e931391 Nikolay Borisov 2020-06-03 1589 &data_reserved, pos, 364ecf3651e086 Qu Wenruo 2017-02-27 1590 write_bytes); c6887cd11149d7 Josef Bacik 2016-03-25 1591 if (ret < 0) { 89f414f96d87ea Qu Wenruo 2020-08-19 1592 size_t tmp = write_bytes; 38d37aa9c32938 Qu Wenruo 2020-06-24 1593 if (btrfs_check_nocow_lock(BTRFS_I(inode), pos, 89f414f96d87ea Qu Wenruo 2020-08-19 1594 &tmp) > 0) { 89f414f96d87ea Qu Wenruo 2020-08-19 1595 ASSERT(tmp == write_bytes); d9d8b2a51a404c Qu Wenruo 2015-09-08 1596 /* d9d8b2a51a404c Qu Wenruo 2015-09-08 1597 * For nodata cow case, no need to reserve d9d8b2a51a404c Qu Wenruo 2015-09-08 1598 * data space. d9d8b2a51a404c Qu Wenruo 2015-09-08 1599 */ 7ee9e4405f264e Josef Bacik 2013-06-21 1600 only_release_metadata = true; 89f414f96d87ea Qu Wenruo 2020-08-19 1601 reserve_bytes = 0; c6887cd11149d7 Josef Bacik 2016-03-25 1602 } else { d0215f3e5ebb58 Josef Bacik 2011-01-25 1603 break; c6887cd11149d7 Josef Bacik 2016-03-25 1604 } c6887cd11149d7 Josef Bacik 2016-03-25 1605 } 1832a6d5ee3b1a Chris Mason 2007-12-21 1606 9f3db423f98c5c Nikolay Borisov 2017-02-20 1607 ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode), 9f3db423f98c5c Nikolay Borisov 2017-02-20 1608 reserve_bytes); 7ee9e4405f264e Josef Bacik 2013-06-21 1609 if (ret) { 7ee9e4405f264e Josef Bacik 2013-06-21 1610 if (!only_release_metadata) 25ce28caaa1ddc Nikolay Borisov 2020-06-03 1611 btrfs_free_reserved_data_space(BTRFS_I(inode), bc42bda22345ef Qu Wenruo 2017-02-27 1612 data_reserved, pos, d9d8b2a51a404c Qu Wenruo 2015-09-08 1613 write_bytes); 8257b2dc3c1a10 Miao Xie 2014-03-06 1614 else 38d37aa9c32938 Qu Wenruo 2020-06-24 1615 btrfs_check_nocow_unlock(BTRFS_I(inode)); 7ee9e4405f264e Josef Bacik 2013-06-21 1616 break; 7ee9e4405f264e Josef Bacik 2013-06-21 1617 } 7ee9e4405f264e Josef Bacik 2013-06-21 1618 376cc685cb3b43 Miao Xie 2013-12-10 1619 again: 89f414f96d87ea Qu Wenruo 2020-08-19 1620 ret = prepare_one_page(inode, &page, pos, write_bytes, b6316429af7f36 Josef Bacik 2011-09-30 1621 force_page_uptodate); 8b62f87bad9cf0 Josef Bacik 2017-10-19 1622 if (ret) { 8b62f87bad9cf0 Josef Bacik 2017-10-19 1623 btrfs_delalloc_release_extents(BTRFS_I(inode), 8702ba9396bf7b Qu Wenruo 2019-10-14 1624 reserve_bytes); d0215f3e5ebb58 Josef Bacik 2011-01-25 1625 break; 8b62f87bad9cf0 Josef Bacik 2017-10-19 1626 } 39279cc3d2704c Chris Mason 2007-06-12 1627 79f015f216539d Goldwyn Rodrigues 2017-10-16 1628 extents_locked = lock_and_cleanup_extent_if_need( 89f414f96d87ea Qu Wenruo 2020-08-19 1629 BTRFS_I(inode), &page, 1, pos, write_bytes, 89f414f96d87ea Qu Wenruo 2020-08-19 1630 &lockstart, &lockend, &cached_state); 79f015f216539d Goldwyn Rodrigues 2017-10-16 1631 if (extents_locked < 0) { 79f015f216539d Goldwyn Rodrigues 2017-10-16 1632 if (extents_locked == -EAGAIN) 376cc685cb3b43 Miao Xie 2013-12-10 1633 goto again; 8b62f87bad9cf0 Josef Bacik 2017-10-19 1634 btrfs_delalloc_release_extents(BTRFS_I(inode), 8702ba9396bf7b Qu Wenruo 2019-10-14 1635 reserve_bytes); 79f015f216539d Goldwyn Rodrigues 2017-10-16 1636 ret = extents_locked; 376cc685cb3b43 Miao Xie 2013-12-10 1637 break; 376cc685cb3b43 Miao Xie 2013-12-10 1638 } 376cc685cb3b43 Miao Xie 2013-12-10 1639 89f414f96d87ea Qu Wenruo 2020-08-19 1640 copied = iov_iter_copy_from_user_atomic(page, i, offset, 89f414f96d87ea Qu Wenruo 2020-08-19 1641 write_bytes); 89f414f96d87ea Qu Wenruo 2020-08-19 1642 flush_dcache_page(page); 56244ef151c3cd Chris Mason 2016-05-16 1643 89f414f96d87ea Qu Wenruo 2020-08-19 1644 if (!PageUptodate(page) && copied < write_bytes) { b1bf862e9dad43 Chris Mason 2011-02-28 1645 /* 89f414f96d87ea Qu Wenruo 2020-08-19 1646 * Short write on non-uptodate page, we must retry and 89f414f96d87ea Qu Wenruo 2020-08-19 1647 * force the page uptodate in next run. b1bf862e9dad43 Chris Mason 2011-02-28 1648 */ 89f414f96d87ea Qu Wenruo 2020-08-19 1649 copied = 0; b6316429af7f36 Josef Bacik 2011-09-30 1650 force_page_uptodate = true; b6316429af7f36 Josef Bacik 2011-09-30 1651 } else { 89f414f96d87ea Qu Wenruo 2020-08-19 1652 /* Next run doesn't need forced uptodate */ b6316429af7f36 Josef Bacik 2011-09-30 1653 force_page_uptodate = false; b6316429af7f36 Josef Bacik 2011-09-30 1654 } 914ee295af418e Xin Zhong 2010-12-09 1655 89f414f96d87ea Qu Wenruo 2020-08-19 1656 iov_iter_advance(i, copied); 485290a734f142 Qu Wenruo 2015-10-29 1657 89f414f96d87ea Qu Wenruo 2020-08-19 1658 if (copied > 0) { 89f414f96d87ea Qu Wenruo 2020-08-19 1659 ret = btrfs_dirty_pages(BTRFS_I(inode), &page, 1, pos, 89f414f96d87ea Qu Wenruo 2020-08-19 1660 copied, &cached_state); 89f414f96d87ea Qu Wenruo 2020-08-19 1661 } else { 89f414f96d87ea Qu Wenruo 2020-08-19 1662 /* No bytes copied, need to free reserved space */ 89f414f96d87ea Qu Wenruo 2020-08-19 1663 if (only_release_metadata) 89f414f96d87ea Qu Wenruo 2020-08-19 1664 btrfs_delalloc_release_metadata(BTRFS_I(inode), 89f414f96d87ea Qu Wenruo 2020-08-19 1665 reserve_bytes, true); 89f414f96d87ea Qu Wenruo 2020-08-19 1666 else 86d52921a2ba51 Nikolay Borisov 2020-06-03 1667 btrfs_delalloc_release_space(BTRFS_I(inode), 89f414f96d87ea Qu Wenruo 2020-08-19 1668 data_reserved, pos, write_bytes, 89f414f96d87ea Qu Wenruo 2020-08-19 1669 true); 485290a734f142 Qu Wenruo 2015-10-29 1670 } 914ee295af418e Xin Zhong 2010-12-09 1671 c67d970f0ea8dc Filipe Manana 2019-09-30 1672 /* c67d970f0ea8dc Filipe Manana 2019-09-30 1673 * If we have not locked the extent range, because the range's c67d970f0ea8dc Filipe Manana 2019-09-30 1674 * start offset is >= i_size, we might still have a non-NULL c67d970f0ea8dc Filipe Manana 2019-09-30 1675 * cached extent state, acquired while marking the extent range c67d970f0ea8dc Filipe Manana 2019-09-30 1676 * as delalloc through btrfs_dirty_pages(). Therefore free any c67d970f0ea8dc Filipe Manana 2019-09-30 1677 * possible cached extent state to avoid a memory leak. c67d970f0ea8dc Filipe Manana 2019-09-30 1678 */ 79f015f216539d Goldwyn Rodrigues 2017-10-16 1679 if (extents_locked) 376cc685cb3b43 Miao Xie 2013-12-10 1680 unlock_extent_cached(&BTRFS_I(inode)->io_tree, e43bbe5e16d87b David Sterba 2017-12-12 1681 lockstart, lockend, &cached_state); c67d970f0ea8dc Filipe Manana 2019-09-30 1682 else c67d970f0ea8dc Filipe Manana 2019-09-30 1683 free_extent_state(cached_state); c67d970f0ea8dc Filipe Manana 2019-09-30 1684 8702ba9396bf7b Qu Wenruo 2019-10-14 1685 btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes); f1de968376340c Miao Xie 2014-01-09 1686 if (ret) { 89f414f96d87ea Qu Wenruo 2020-08-19 1687 btrfs_drop_pages(&page, 1); d0215f3e5ebb58 Josef Bacik 2011-01-25 1688 break; f1de968376340c Miao Xie 2014-01-09 1689 } 39279cc3d2704c Chris Mason 2007-06-12 1690 89f414f96d87ea Qu Wenruo 2020-08-19 1691 if (only_release_metadata) { 38d37aa9c32938 Qu Wenruo 2020-06-24 1692 btrfs_check_nocow_unlock(BTRFS_I(inode)); da17066c40472c Jeff Mahoney 2016-06-15 1693 lockstart = round_down(pos, 0b246afa62b0cf Jeff Mahoney 2016-06-22 1694 fs_info->sectorsize); 89f414f96d87ea Qu Wenruo 2020-08-19 1695 lockend = lockstart + PAGE_SIZE - 1; 7ee9e4405f264e Josef Bacik 2013-06-21 1696 7ee9e4405f264e Josef Bacik 2013-06-21 1697 set_extent_bit(&BTRFS_I(inode)->io_tree, lockstart, 7ee9e4405f264e Josef Bacik 2013-06-21 1698 lockend, EXTENT_NORESERVE, NULL, 7ee9e4405f264e Josef Bacik 2013-06-21 1699 NULL, GFP_NOFS); 7ee9e4405f264e Josef Bacik 2013-06-21 1700 } 7ee9e4405f264e Josef Bacik 2013-06-21 1701 89f414f96d87ea Qu Wenruo 2020-08-19 1702 btrfs_drop_pages(&page, 1); f1de968376340c Miao Xie 2014-01-09 1703 d0215f3e5ebb58 Josef Bacik 2011-01-25 1704 cond_resched(); d0215f3e5ebb58 Josef Bacik 2011-01-25 1705 d0e1d66b5aa1ec Namjae Jeon 2012-12-11 1706 balance_dirty_pages_ratelimited(inode->i_mapping); cb843a6f513a1a Chris Mason 2008-10-03 1707 914ee295af418e Xin Zhong 2010-12-09 1708 pos += copied; 914ee295af418e Xin Zhong 2010-12-09 1709 num_written += copied; d0215f3e5ebb58 Josef Bacik 2011-01-25 1710 } 39279cc3d2704c Chris Mason 2007-06-12 1711 364ecf3651e086 Qu Wenruo 2017-02-27 1712 extent_changeset_free(data_reserved); d0215f3e5ebb58 Josef Bacik 2011-01-25 1713 return num_written ? num_written : ret; 39279cc3d2704c Chris Mason 2007-06-12 1714 } d0215f3e5ebb58 Josef Bacik 2011-01-25 1715 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org