On Saturday, 7 July 2007 13:31, Pavel Machek wrote: > Hi! > > > > I don't think we can do that. I suspect rename looks like: > > > > > > write directory entry in source > > > A) (uninterruptible wait for write) > > > write directory entry in destination > > > (uninterruptible wait for write) > > > write something else > > > > > > If we freeze some task in place "A)", we'll write to the disk when the > > > directory write is finished :-(. > > > > Renaming is a single syscall, so won't the process get frozen when the > > syscall > > finishes? > > It would be frozen when syscall finishes. But if we freeze it at A) > point, we have a problem.
With this patch, we don't freeze it. :-) We do something like "send a freeze request to this task, but don't care if it doesn't freeze". Now, IMHO, the correctness here is the question of for how long a task can be in TASK_UNINTERRUPTIBLE it it's not stuck (eg. the resource needed is gone indefinitely, like in NFS) and I think that's not very long. For example, if the tasks sleeps on a mutex, then it waits for another task to release the mutex (interrupt handlers don't use mutexes) and I don't know of any realistic scenario in which it can last in that state throughout freeze_processes(). Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
