[Ocfs2-devel] [PATCH 1/2] JBD2: Allow feature checks before journal recovery
Jan Kara
jack at suse.cz
Wed Jul 21 10:27:21 PDT 2010
> Before we start accessing a huge (> 16 TiB) OCFS2 volume, we need to
> confirm that its journal supports 64-bit offsets. So we need to check
> the journal's feature bits before recovering the journal.
>
> This is not possible with JBD2 at present, because the journal
> superblock (where the feature bits reside) is not loaded from disk until
> the journal is recovered.
>
> This patch loads the journal superblock in
> jbd2_journal_check_used_features() if it has not already been loaded,
> allowing us to check the feature bits before journal recovery.
>
> Signed-off-by: Patrick LoPresti <lopresti at gmail.com>
>
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index bc2ff59..c5a864f 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -1365,6 +1365,8 @@ int jbd2_journal_check_used_features (journal_t *journal, unsigned long compat,
>
> if (!compat && !ro && !incompat)
> return 1;
> + if (journal_get_superblock(journal))
> + return 0;
> if (journal->j_format_version == 1)
> return 0;
This looks OK in principle. It would be even nicer to avoid all the checks
journal_get_superblock() when the superblock is actually loaded so that we
don't do them each time jbd2_journal_check_used_features is called...
Honza
--
Jan Kara <jack at suse.cz>
SuSE CR Labs
More information about the Ocfs2-devel
mailing list