On Tue, 5 Aug 2008 02:05:20 +0100 "Duane Griffin" <duaneg@xxxxxxxxx> wrote: > The __log_wait_for_space function sits in a loop checkpointing transactions > until there is sufficient space free in the journal. However, if there are > no transactions to be processed (e.g. because the free space calculation is > wrong due to a corrupted filesystem) it will never progress. > > Check for space being required when no transactions are outstanding and > abort the journal instead of endlessly looping. > > This patch fixes the bug reported by Sami Liedes at: > http://bugzilla.kernel.org/show_bug.cgi?id=10976 > > Signed-off-by: Duane Griffin <duaneg@xxxxxxxxx> > --- > diff --git a/fs/jbd/checkpoint.c b/fs/jbd/checkpoint.c > index a5432bb..af2b554 100644 > --- a/fs/jbd/checkpoint.c > +++ b/fs/jbd/checkpoint.c > @@ -126,13 +126,24 @@ void __log_wait_for_space(journal_t *journal) > > /* > * Test again, another process may have checkpointed while we > - * were waiting for the checkpoint lock > + * were waiting for the checkpoint lock. If there are no > + * outstanding transactions there is nothing to checkpoint and > + * we can't make progress. Abort the journal in this case. > */ > spin_lock(&journal->j_state_lock); > nblocks = jbd_space_needed(journal); > if (__log_space_left(journal) < nblocks) { > + int chkpt = journal->j_checkpoint_transactions != NULL; > + > spin_unlock(&journal->j_state_lock); > - log_do_checkpoint(journal); > + if (chkpt) { > + log_do_checkpoint(journal); > + } else { > + printk(KERN_ERR "%s: no transactions\n", > + __func__); > + journal_abort(journal, 0); > + } > + > spin_lock(&journal->j_state_lock); > } > mutex_unlock(&journal->j_checkpoint_mutex); umm, OK, but... There's not really a lot of point in testing journal->j_checkpoint_transactions inside j_state_lock, is there? Hence local variable chkpt isn't really needed. But log_do_checkpoint() already checks to see if there are any checkpointing transactions upon which to operate, so rather than doing log_do_checkpoint()'s work for it, perhaps it would be cleaner to teach log_do_checkpoint() to tell the caller whether it manage to do any work? The nice thing about that is that even if journal->j_checkpoint_transactions is NULL, log_do_checkpoint() might still be able to do some useful work in cleanup_journal_tail(). otoh, two existing callers of log_do_checkpoint() already test journal->j_checkpoint_transactions before calling log_do_checkpoint(), so maybe that's pretty pointless. otoh2, those existing callers do the seemingly-unneeded spin_lock(j_list_lock). hrm. So if we're playing match-the-existing code, we should go with your first patches. ho hum, I guess I'll do "otoh2". -- 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
