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SubjectRe: [PATCH] jbd2: clear JBD2_ABORT flag before journal_reset to update log tail info when load journal
Thanks for the patch! Just some small comments below:

On Sat 11-01-20 10:25:42, Kai Li wrote:
> Fixes: 85e0c4e89c1b "jbd2: if the journal is aborted then don't allow update of the log tail"

This tag should come at the bottom of the changelog (close to your
Signed-off-by).

> If journal is dirty when mount, it will be replayed but jbd2 sb
> log tail cannot be updated to mark a new start because
> journal->j_flags has already been set with JBD2_ABORT first
> in journal_init_common.
> When a new transaction is committed, it will be recorded in block 1
> first(journal->j_tail is set to 1 in journal_reset). If emergency
> restart again before journal super block is updated unfortunately,
> the new recorded trans will not be replayed in the next mount.
> It is danerous which may lead to metadata corruption for file system.

I'd slightly rephrase the text here so that it is more easily readable and
correct some grammar mistakes. Something like:

If the journal is dirty when the filesystem is mounted, jbd2 will replay
the journal but the journal superblock will not be updated by
journal_reset() because JBD2_ABORT flag is still set (it was set in
journal_init_common()). This is problematic because when a new transaction
is then committed, it will be recorded in block 1 (journal->j_tail was set
to 1 in journal_reset()). If unclean shutdown happens again before the
journal superblock is updated, the new recorded transaction will not be
replayed during the next mount (because of stale sb->s_start and
sb->s_sequence values) which can lead to filesystem corruption.

Otherwise the patch looks good to me so feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

(again this is added to the bottom of the changelog like the 'Fixes' tag or
'Signed-off-by' tag).

Honza

>
> Signed-off-by: Kai Li <li.kai4@h3c.com>
> ---
> fs/jbd2/journal.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index 5e408ee24a1a..069b22eba795 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -1710,6 +1710,11 @@ int jbd2_journal_load(journal_t *journal)
> journal->j_devname);
> return -EFSCORRUPTED;
> }
> + /*
> + * clear JBD2_ABORT flag initialized in journal_init_common
> + * here to update log tail information with the newest seq.
> + */
> + journal->j_flags &= ~JBD2_ABORT;
>
> /* OK, we've finished with the dynamic journal bits:
> * reinitialise the dynamic contents of the superblock in memory
> @@ -1717,7 +1722,6 @@ int jbd2_journal_load(journal_t *journal)
> if (journal_reset(journal))
> goto recovery_error;
>
> - journal->j_flags &= ~JBD2_ABORT;
> journal->j_flags |= JBD2_LOADED;
> return 0;
>
> --
> 2.24.0.windows.2
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR

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