I have restarted the delete service. And unfortunately it happened again.
I am confuse that:
1. When will an anon bdev be allocated in btrfs?
2. When will an anon bdev return to the pool?
3. Are there any tools to find out how many subvolumes have been
deleted but not committed?
Thanks
On Thu, Jun 18, 2020 at 8:34 PM David Sterba <dsterba@xxxxxxx> wrote:
>
> On Mon, Jun 15, 2020 at 08:50:28PM +0800, Greed Rong wrote:
> > Does that mean about 2^20 subvolumes can be created in one root btrfs?
>
> No, subvolume ids are assigned incrementally, the amount is 2^64 so this
> shouldn't be a problem in practice.
>
> > The snapshot delete service was stopped a few weeks ago. I think this
> > is the reason why the id pool is exhausted.
> > I will try to run it again and see if it works.
>
> The patches to reclaim the anon bdevs faster is small enough to be
> pushed to older stable kernels, so you should be able to use it
> eventually.
>
> As a workaround, you can still delete the old subvolumes to get the
> space back but perhaps at a slower rate and wait until the deleted
> subvolumes are cleaned. That there's no way to get the number of used
> anon bdevs makes it harder unfortunatelly.
