On Fri, May 19, 2017 at 03:08:22PM +0200, David Sterba wrote: > On Thu, May 18, 2017 at 05:42:24PM -0700, Liu Bo wrote: > > On Tue, May 16, 2017 at 07:10:38PM +0200, David Sterba wrote: > > > flush_all_writes is an atomic but does not use the semantics at all, > > > it's just on/off indicator, we can use bool. > > > > > > > It might use atomic to avoid reordering, but I'm not sure if > > reordering could really happen here. > > Ok, I'll have a look. It does not seem to rely on atomics/ordering though. The semantics of atomic_t to not lose concurrent increment/decrement is not used here. The variable is always used within the following patterns: set to 1 submit writes wait for completion set to 0 or if set: submit writes The potential ordering issues, eg. when the worker thread that just reads the value will not see the value 1 from other thread would need to keep the state out of sync overal several mutex lock/unlock calls, that imply a barrier anyway. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
