On Thu, May 18, 2017, at 08:20 PM, Darrick J. Wong wrote: > Therefore, add a reboot hook to freeze all filesystems (which in general > will induce ext4/xfs/btrfs to checkpoint the log) just prior to reboot. > This is an unfortunate and insufficient workaround for multiple layers > of inadequate external software, but at least it will reduce boot time > surprises for the "OS updater failed to disengage the filesystem before > rebooting" case. As a maintainer of one of those userspace tools (https://github.com/ostreedev/ostree), which I don't think is the one in question here, but likely has the same issue - I'd like to have some sort of API to fix this - maybe flush the journal *without* remounting r/o? Unlike the case you're talking about with rebooting into a special update mode, libostree constructs a new root with hardlinks while the system is running. Hence, system downtime is just reboot, like dual-partition update systems, except we're more flexible. Although hm...I guess an API to flush the journal would only narrow the race. Is the single partition case really just doomed?
