I'm running 4.4.106-1.el7.elrepo.x86_64 and I do a btrfs balance everynight.
Every night I'm getting a kernel hang, sometimes caught by my watchdog, sometimes not. Last night's hang was on the balance of DATA on / at 70. I'm not sure how to further trace this down to help you -- the console by the time I notice just has lots of messages on it without the initial ones. The last items in /var/log/message aren't helpful, but I'm pretty sure it is the nightly balance. I've run btrfs check on / with no issues recently. Rich -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html