From 21b5bef20ef89795882f0b1bf5517fb283c16461 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Fri, 16 Feb 2024 14:33:41 +1030 Subject: [PATCH] btrfs: make __extent_writepage_io() to write specified range only Function __extent_writepage_io() is designed to find all dirty ranges of a page, and add the dirty ranges to the bio_ctrl for submission. It requires all the dirtied ranges to be covered by an ordered extent. It gets called in two locations, but one call site is not subpage aware: - __extent_writepage() It gets called when writepage_delalloc() returned 0, which means writepage_delalloc() has handled delalloc for all subpage sectors inside the page. So this call site is OK. - extent_write_locked_range() This call site is utilized by zoned support, and in this case, we may only run delalloc range for a subset of the page, like this: (64K page size) 0 16K 32K 48K 64K |/////| |///////| | In the above case, if extent_write_locked_range() is only triggered for range [0, 16K), __extent_writepage_io() would still try to submit the dirty range of [32K, 48K), then it would not find any ordered extent for it and triggers various ASSERT()s. Fix this problem by: - Introducing @start and @len parameters to specify the range For the first call site, we just pass the whole page, and the behavior is not touched, since run_delalloc_range() for the page should have created all ordered extents for the page. For the second call site, we avoid touching anything beyond the range, thus avoiding the dirty range which is not yet covered by any delalloc range. - Making btrfs_folio_assert_not_dirty() subpage aware The only caller is inside __extent_writepage_io(), and since that caller now accepts a subpage range, we should also check the subpage range other than the whole page. Reviewed-by: Johannes Thumshirn Reviewed-by: Naohiro Aota Signed-off-by: Qu Wenruo Signed-off-by: David Sterba --- fs/btrfs/extent_io.c | 18 +++++++++++------- fs/btrfs/subpage.c | 22 ++++++++++++++++------ fs/btrfs/subpage.h | 3 ++- 3 files changed, 29 insertions(+), 14 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 7ae1bd91f182..643243a0a010 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -1339,20 +1339,23 @@ static void find_next_dirty_byte(struct btrfs_fs_info *fs_info, * < 0 if there were errors (page still locked) */ static noinline_for_stack int __extent_writepage_io(struct btrfs_inode *inode, - struct page *page, + struct page *page, u64 start, u32 len, struct btrfs_bio_ctrl *bio_ctrl, loff_t i_size, int *nr_ret) { struct btrfs_fs_info *fs_info = inode->root->fs_info; - u64 cur = page_offset(page); - u64 end = cur + PAGE_SIZE - 1; + u64 cur = start; + u64 end = start + len - 1; u64 extent_offset; u64 block_start; struct extent_map *em; int ret = 0; int nr = 0; + ASSERT(start >= page_offset(page) && + start + len <= page_offset(page) + PAGE_SIZE); + ret = btrfs_writepage_cow_fixup(page); if (ret) { /* Fixup worker will requeue */ @@ -1441,7 +1444,7 @@ static noinline_for_stack int __extent_writepage_io(struct btrfs_inode *inode, nr++; } - btrfs_folio_assert_not_dirty(fs_info, page_folio(page)); + btrfs_folio_assert_not_dirty(fs_info, page_folio(page), start, len); *nr_ret = nr; return 0; @@ -1499,7 +1502,8 @@ static int __extent_writepage(struct page *page, struct btrfs_bio_ctrl *bio_ctrl if (ret) goto done; - ret = __extent_writepage_io(BTRFS_I(inode), page, bio_ctrl, i_size, &nr); + ret = __extent_writepage_io(BTRFS_I(inode), page, page_offset(page), + PAGE_SIZE, bio_ctrl, i_size, &nr); if (ret == 1) return 0; @@ -2251,8 +2255,8 @@ void extent_write_locked_range(struct inode *inode, struct page *locked_page, clear_page_dirty_for_io(page); } - ret = __extent_writepage_io(BTRFS_I(inode), page, &bio_ctrl, - i_size, &nr); + ret = __extent_writepage_io(BTRFS_I(inode), page, cur, cur_len, + &bio_ctrl, i_size, &nr); if (ret == 1) goto next_page; diff --git a/fs/btrfs/subpage.c b/fs/btrfs/subpage.c index 86468305cd73..6947a6f3d9d8 100644 --- a/fs/btrfs/subpage.c +++ b/fs/btrfs/subpage.c @@ -703,19 +703,29 @@ IMPLEMENT_BTRFS_PAGE_OPS(checked, folio_set_checked, folio_clear_checked, * Make sure not only the page dirty bit is cleared, but also subpage dirty bit * is cleared. */ -void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info, struct folio *folio) +void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info, + struct folio *folio, u64 start, u32 len) { - struct btrfs_subpage *subpage = folio_get_private(folio); + struct btrfs_subpage *subpage; + unsigned int start_bit; + unsigned int nbits; + unsigned long flags; if (!IS_ENABLED(CONFIG_BTRFS_ASSERT)) return; - ASSERT(!folio_test_dirty(folio)); - if (!btrfs_is_subpage(fs_info, folio->mapping)) + if (!btrfs_is_subpage(fs_info, folio->mapping)) { + ASSERT(!folio_test_dirty(folio)); return; + } - ASSERT(folio_test_private(folio) && folio_get_private(folio)); - ASSERT(subpage_test_bitmap_all_zero(fs_info, subpage, dirty)); + start_bit = subpage_calc_start_bit(fs_info, folio, dirty, start, len); + nbits = len >> fs_info->sectorsize_bits; + subpage = folio_get_private(folio); + ASSERT(subpage); + spin_lock_irqsave(&subpage->lock, flags); + ASSERT(bitmap_test_range_all_zero(subpage->bitmaps, start_bit, nbits)); + spin_unlock_irqrestore(&subpage->lock, flags); } /* diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h index b6dc013b0fdc..4b363d9453af 100644 --- a/fs/btrfs/subpage.h +++ b/fs/btrfs/subpage.h @@ -156,7 +156,8 @@ DECLARE_BTRFS_SUBPAGE_OPS(checked); bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info, struct folio *folio, u64 start, u32 len); -void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info, struct folio *folio); +void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info, + struct folio *folio, u64 start, u32 len); void btrfs_folio_unlock_writer(struct btrfs_fs_info *fs_info, struct folio *folio, u64 start, u32 len); void __cold btrfs_subpage_dump_bitmap(const struct btrfs_fs_info *fs_info, -- 2.49.0