On 02/26, Weichao Guo wrote:
> There is a potential inconsistent metadata case due to a cp block
> crc invalid in the latest checkpoint caused by hardware issues:
> 1) write nodes into segment x;
> 2) write checkpoint A;
> 3) remove nodes in segment x;
> 4) write checkpoint B;
> 5) issue discard or write datas into segment x;
> 6) sudden power-cut;
> 7) use checkpoint A after reboot as checkpoint B is invalid
>
> This inconsistency may be found after several reboots long time
> later and the kernel log about cp block crc invalid has disappeared.
> This makes the root cause of the inconsistency is hard to locate.
> Let us separate such other part issues from f2fs logical bugs in
> debug version, and try to validate the checkpoint with the backup
> when cp2 is corrupted.
How can you guarantee it happened caused by real power-cut during checkpoint?
Does it really make sense to write addition block at every checkpoint?
>
> Signed-off-by: Weichao Guo <guoweic...@huawei.com>
> ---
> fs/f2fs/checkpoint.c | 27 +++++++++++++++++++++++----
> 1 file changed, 23 insertions(+), 4 deletions(-)
>
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 512dca8..81c4acd 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -761,15 +761,29 @@ static struct page *validate_checkpoint(struct
> f2fs_sb_info *sbi,
>
> err = get_checkpoint_version(sbi, cp_addr, &cp_block,
> &cp_page_1, version);
> - if (err)
> + if (err) {
> + f2fs_msg(sbi->sb, KERN_WARNING,
> + "corrupted cp1 at blk_addr: 0x%x", cp_addr);
> + f2fs_bug_on(sbi, 1);
> goto invalid_cp1;
> + }
> pre_version = *version;
>
> cp_addr += le32_to_cpu(cp_block->cp_pack_total_block_count) - 1;
> err = get_checkpoint_version(sbi, cp_addr, &cp_block,
> &cp_page_2, version);
> - if (err)
> - goto invalid_cp2;
> + if (err) {
> + err = get_checkpoint_version(sbi, cp_addr + 1, &cp_block,
> + &cp_page_2, version);
> + if (err) {
> + goto invalid_cp2;
> + }
> + else if (*version == pre_version) {
> + f2fs_msg(sbi->sb, KERN_WARNING,
> + "corrupted cp2 at blk_addr: 0x%x", cp_addr);
> + f2fs_bug_on(sbi, 1);
> + }
> + }
> cur_version = *version;
>
> if (cur_version == pre_version) {
> @@ -1302,7 +1316,12 @@ static int do_checkpoint(struct f2fs_sb_info *sbi,
> struct cp_control *cpc)
> }
>
> /* writeout checkpoint block */
> - update_meta_page(sbi, ckpt, start_blk);
> + update_meta_page(sbi, ckpt, start_blk++);
> + /* writeout a backup of cp2 if available */
> + if (!enabled_nat_bits(sbi, cpc) ||
> + (ckpt->cp_pack_total_block_count + 1 <=
> + sbi->blocks_per_seg - NM_I(sbi)->nat_bits_blocks))
> + update_meta_page(sbi, ckpt, start_blk);
>
> /* wait for previous submitted node/meta pages writeback */
> wait_on_all_pages_writeback(sbi);
> --
> 2.10.1
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