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Message-ID: <63049B47.2000408@huawei.com> Date: Tue, 23 Aug 2022 17:17:59 +0800 From: yebin <yebin10@...wei.com> To: Jan Kara <jack@...e.cz> CC: <tytso@....edu>, <adilger.kernel@...ger.ca>, <linux-ext4@...r.kernel.org>, <linux-kernel@...r.kernel.org> Subject: Re: [PATCH RFC] jbd2: detect old record when do journal scan On 2022/8/19 17:54, Jan Kara wrote: > 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@...wei.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 The file system corruption I encountered was indeed because e2fsprogs did not update journal - > J_ transaction_ Sequence leads to replay the old transaction. So I wonder whether the kernel should detect this kind of exception, at least when there is a file system corruption, there are clues to trace. > >> --- >> 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 >>
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