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SubjectRe: [PATCH RFC] jbd2: detect old record when do journal scan
On Wed 10-08-22 09:34:42, Ye Bin wrote:
> As https://github.com/tytso/e2fsprogs/issues/120 describe tune2fs do not update
> j_tail_sequence when do journal recovery. This maybe recover old journal record,
> then will lead to file system corruption.
> To avoid file system corruption in this case, if detect current transaction's
> commit time earlier than previous transaction's commit time when do journal
> scan, just return error.
>
> Signed-off-by: Ye Bin <yebin10@huawei.com>

Thanks for the patch! Let me see if I understand your concern right. You
are concerned about the following scenario:

1) Kernel uses the filesystem, there's a crash.
2) E2fsprogs replays the journal but fails to update sb->s_sequence in the
journal superblock.
3) Kernel mounts the fs again - however note that even if kernel skips
recovery, it does scan the journal jbd2_journal_skip_recovery() and
journal->j_transaction_sequence is set based on the last transaction found
in the journal.

So I don't think there is really possibility we will quickly reuse some
transaction IDs and thus possibility of corruption on replay? Am I missing
something?

Honza


> ---
> fs/jbd2/recovery.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
> index f548479615c6..f3def21a96a5 100644
> --- a/fs/jbd2/recovery.c
> +++ b/fs/jbd2/recovery.c
> @@ -812,8 +812,17 @@ static int do_one_pass(journal_t *journal,
> break;
> }
> }
> - if (pass == PASS_SCAN)
> + if (pass == PASS_SCAN) {
> + if (commit_time < last_trans_commit_time) {
> + pr_err("JBD2: old journal record found "
> + "in transaction %u\n",
> + next_commit_ID);
> + err = -EFSBADCRC;
> + brelse(bh);
> + goto failed;
> + }
> last_trans_commit_time = commit_time;
> + }
> brelse(bh);
> next_commit_ID++;
> continue;
> --
> 2.31.1
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR

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