| Message ID | 871vbax86w.fsf@patl.com |
|---|---|
| State | Superseded, archived |
| Headers | show |
> 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@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
On Wed, Jul 21, 2010 at 10:27 AM, Jan Kara <jack@suse.cz> wrote: >> Signed-off-by: Patrick LoPresti <lopresti@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... How about this? if (!compat && !ro && !incompat) return 1; + if (journal->j_format_version == 0 && journal_get_superblock(journal) != 0) + return 0; if (journal->j_format_version == 1) return 0; journal_init_common() uses kzalloc() to allocate the journal_t, and journal_get_superblock() fills it in, so I believe this is a valid test. - Pat -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> On Wed, Jul 21, 2010 at 10:27 AM, Jan Kara <jack@suse.cz> wrote: > >> Signed-off-by: Patrick LoPresti <lopresti@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... > > How about this? > > if (!compat && !ro && !incompat) > return 1; > + if (journal->j_format_version == 0 && > journal_get_superblock(journal) != 0) > + return 0; > if (journal->j_format_version == 1) > return 0; > > journal_init_common() uses kzalloc() to allocate the journal_t, and > journal_get_superblock() fills it in, so I believe this is a valid > test. Yes, this looks OK. Just add a comment before the check like /* Load journal super block if it isn't loaded yet */ Honza
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;
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@gmail.com> -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html