From 8b7de4d0084fea24576f39c4e4fcda7b42515761 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Fri, 29 May 2020 17:29:47 +0800 Subject: [PATCH] f2fs: fix wrong discard space Under heavy fsstress, we may triggle panic while issuing discard, because __check_sit_bitmap() detects that discard command may earse valid data blocks, the root cause is as below race stack described, since we removed lock when flushing quota data, quota data writeback may race with write_checkpoint(), so that it causes inconsistency in between cached discard entry and segment bitmap. - f2fs_write_checkpoint - block_operations - set_sbi_flag(sbi, SBI_QUOTA_SKIP_FLUSH) - f2fs_flush_sit_entries - add_discard_addrs - __set_bit_le(i, (void *)de->discard_map); - f2fs_write_data_pages - f2fs_write_single_data_page : inode is quota one, cp_rwsem won't be locked - f2fs_do_write_data_page - f2fs_allocate_data_block - f2fs_wait_discard_bio : discard entry has not been added yet. - update_sit_entry - f2fs_clear_prefree_segments - f2fs_issue_discard : add discard entry In order to fix this, this patch uses node_write to serialize f2fs_allocate_data_block and checkpoint. Fixes: 435cbab95e39 ("f2fs: fix quota_sync failure due to f2fs_lock_op") Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/segment.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 0429bdce8177..e4898789c5c0 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -3106,6 +3106,14 @@ void f2fs_allocate_data_block(struct f2fs_sb_info *sbi, struct page *page, type = CURSEG_COLD_DATA; } + /* + * We need to wait for node_write to avoid block allocation during + * checkpoint. This can only happen to quota writes which can cause + * the below discard race condition. + */ + if (IS_DATASEG(type)) + down_write(&sbi->node_write); + down_read(&SM_I(sbi)->curseg_lock); mutex_lock(&curseg->curseg_mutex); @@ -3171,6 +3179,9 @@ void f2fs_allocate_data_block(struct f2fs_sb_info *sbi, struct page *page, up_read(&SM_I(sbi)->curseg_lock); + if (IS_DATASEG(type)) + up_write(&sbi->node_write); + if (put_pin_sem) up_read(&sbi->pin_sem); }