On Mon, Jan 23, 2017 at 3:23 PM, Pavel Emelyanov <xemul@xxxxxxxxxxxxx> wrote: > On 01/23/2017 11:47 AM, Amir Goldstein wrote: >> On Thu, Jan 19, 2017 at 2:13 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote: >>> freeze/thaw of upper is all that is needed. >>> >> >> Miklos, >> >> Looking at it again, I believe that not even that is needed. >> Having fixed ovl_sync_fs() with patch #2, ovl_freeze() >> and ovl_unfreeze() need to be NOP. Am I right? >> >> In fact, freezing upper fs, when many overlayfs mounts >> share the same base fs (a-la docker) would be quite lame. >> >> WRT other use cases of freezing overlayfs, I am not sure >> if it is needed for correctness of docker checkpoint/restart? >> >> Pavel? > > Thanks for the heads-up :) > > Good question. Actually we haven't yet experimented with doing _full_ > (with FS) snapshot of containers, but at the first glance I can't > see the need for OVL freeze :( We stop all the processes in entry.S > effectively, so no in-flight IO can be happening. > Serge, Stephan, Same question. Would lxc-snapshot gain anything from the ability to fsfreeze an overlay mount? Basically, it should give you the ability to create a consistent snapshot of overlayfs upper dir from a running container, but maybe you already do that by freezing the container processes? I couldn't figure that out from lxc-snapshot documentation. The context is that I implemented overlayfs fsfreeze for my own needs, but I need other use cases to justify merging the feature. Thanks, Amir. -- To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
