On 05/25/2010 09:07 PM, Sukadev Bhattiprolu wrote: > If process P1 has a F_WRLCK lease on file F1 and process P2 opens the > file, P2's open() blocks for lease_break_time (45 seconds) and P1 gets > a SIGIO to cleanup it lease in preparation for P2's open. If the two > processes are checkpointed/restarted in this window, we should address > following two issues: > > - P1 should get a SIGIO only once for the lease (i.e if P1 got the > SIGIO before checkpoint, it should not get the SIGIO after restart). The qualification "before" is vague in our case - a checkpoint is potentially a length operation, so before *which part* of the checkpoint you mean here ? > > - If R seconds remain in the lease, P2's open should be blocked for > at least the R seconds, so P1 has the time to clean up its lease. > The previous patch gives P1 the entire lease_break_time but that > can leave P2 stalled for 2*lease_break_time. > > To address first, we add a field ->fl_break_notified to "remember" if we > notified the lease-holder already. We save this field in the checkpoint > image and when restarting, we notify the lease-holder only if this field > is not set. I'm not sure I understand. Signals are saved last, in particular they are saved after files, and file leases. What happens if we at checkpoint, we look at a file lease - we save the least_break_time, now we proceed with the checkpoint, now the lease expires before we are done, so we get a signal, and finally we save the signals. In this case, we get both an expiry time and the signal recorded. (Am I mis-reading the code ?) It seems to me that we need to mark the file lease at checkpoint to prevent the signal from being sent until _after_ the checkpoint ends (as opposed to remembering that the signal was sent). And then at the end of the checkpoint, iterate through the leases for each marked lease - remove the mark and fire the signal. Oren. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
