> 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@xxxxxxxxx> > > 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@xxxxxxx> SuSE CR Labs -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
