[sheepdog] [PATCH v3 3/7] sheep: teach journal file to handle epoch and config write

[Hitoshi Mitake]

> > 
> >>  	if (uatomic_is_true(&sys->use_journal) &&
> >> -	    journal_file_write(oid, iocb->buf, iocb->length, iocb->offset,
> >> -			       false)
> >> +	    journal_write_store(oid, iocb->buf, iocb->length, iocb->offset,
> >> +				false)
> >>  	    != SD_RES_SUCCESS) {
> >>  		sd_eprintf("turn off journaling");
> >>  		uatomic_set_false(&sys->use_journal);
> > 
> > Is this behavior, turning off journaling and continuing, suitable?
> > From my perspective, at least a behavior which causes death of sheep
> > when writing journal fails should be supported as an optional one.
> > 
> 
> Your advice is reasonable, but the error handling would be better
> considered when journaling is set as default. Let's keep this patch set
> small.

Simply causing panic() makes the patchset smaller. I feel the current
behavior is too dangerous because users have no way to know disabling
of journals until they read the log messages.

Thanks,
Hitoshi