On Tue, 3 Oct 2017, Luis R. Rodriguez wrote: > This uses the existing filesystem freeze and thaw callbacks to > freeze each filesystem on suspend/hibernation and thaw upon resume. > > This is needed so that we properly really stop IO in flight without > races after userspace has been frozen. Without this we rely on > kthread freezing and its semantics are loose and error prone. > For instance, even though a kthread may use try_to_freeze() and end > up being frozen we have no way of being sure that everything that > has been spawned asynchronously from it (such as timers) have also > been stopped as well. > > A long term advantage of also adding filesystem freeze / thawing > supporting durign suspend / hibernation is that long term we may > be able to eventually drop the kernel's thread freezing completely > as it was originally added to stop disk IO in flight as we hibernate > or suspend. > > This also implies that many kthread users exist which have been > adding freezer semantics onto its kthreads without need. These also > will need to be reviewed later. > > This is based on prior work originally by Rafael Wysocki and later by > Jiri Kosina. > > Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx> Thanks a lot for picking this up; I never found time to actually finalize it. Acked-by: Jiri Kosina <jkosina@xxxxxxx> for patches 2 and 5 (the fs agnostic code), which were in the core of my original work. -- Jiri Kosina SUSE Labs
