On Mon, Nov 7, 2016 at 11:07 AM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote: > On Sun, Nov 6, 2016 at 8:14 PM, Konstantin Khlebnikov <koct9i@xxxxxxxxx> wrote: >> On Wed, Oct 26, 2016 at 2:12 PM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote: >>> On Tue, Oct 25, 2016 at 1:57 PM, Raphael Hertzog <hertzog@xxxxxxxxxx> wrote: >>> >>>> Do you plan to make it the default in the future when it has been >>>> available for a while? >>>> >>>> Barring any regression introduced by your patch, it seems that the feature >>>> is best available by default since it allows legitimate operations to >>>> succeed that are otherwise refused. I understand that it makes it >>>> impossible to mount the overlay filesystem with an older kernel but is >>>> that problem more widespread than the one we're fixing here? On my side, >>>> overlayfs is only used in scenarios where the kernel is always the same >>>> (or newer compared to what created the initial filesystem). >>> >>> I think it would be safe to make it the default if upperdir is empty. >>> Nonempty implies that it was created with old kernel (or it was >>> crafted by hand). But there should be a way to explicitly turn it >>> off; either because of the need for backward compatibility or because >>> the old format is simply easier to work with for humans. >>> >>> How about: >>> >>> - If upper is nonempty, then leave redirect feature alone except when >>> mount option "-oredirect=on" is used to force enabling it. >>> - If upper is empty, then enable redirect feature except when mount >>> option "-oredirect=off" is used to force disabling it. >> >> I don't like this empty-nonempty upper logic. >> >> I think this feature should be off by default and be enabled >> explicitly in mount option. >> Available features could be listed in sysfs /sys/fs/overlay/..., like ext4 does. >> >> Overlayfs mounting anyway is complicated operation. >> User must know a lot about it and provide persistent state for each mount: >> list layers in correct order, work and uppder directory on the same disk, etc. >> Enabled features is a part of this state. >> >> Probably this could be solved in userspace tool "mount.overlay" - it could load >> features and layers from config file or xattr and set required mount >> options automatically. > > It seems there are some conflicting opinions here. I have mine too, > but I'll let this simmer and concentrate on actual features for now. Ok =) let's try keep as simple as possible. I've stumbled on somehow related problem - concurrent copy-ups are strictly serialized by rename locks. Obviously, file copying could be done in parallel: locks are required only for final rename. Because of that overlay slower that aufs for some workloads. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
