Re: New file system with same issue

[Marc Haber <mh+linux-btrfs@zugschlus.de>]

On Mon, Mar 14, 2016 at 01:48:18PM +0100, Holger Hoffstätte wrote:
> On 03/14/16 13:07, Marc Haber wrote:
> >> And btrfs balance runs into the same ENOSPC issues as the old one:
> > 
> > ... with Qu's patch, I now get a reproducible kernel trace:
> 
> <snip>
> 
> That is interesting and useful. Sorry if this was asked before, but
> did you ever try to clear the free-space cache via -o clear_cache
> on mount?

This was not asked, and I didn't try. Since this is an encrypted root
filesystem, is it a workable way to add clear_cache to /etc/fstab,
rebuild initramfs and reboot? Or do you recommend using a rescue system?

> Give it a try, let it run for a while and then try balancing
> again.

Do I need to wait for clear_cache to finish, like until I see disk
usage dropping?

> Uncle Occam's razor also suggests that the involvement of dm
> doesn't help. Why not just use the device/partition directly?

I need the dm intermediate since I don't want to repartition the
expensive SSD and the entire system is crypted.

> _Someone_ is lying to btrfs in terms of device size and/or allocated
> chunks, otherwise you wouldn't get the ENOSPC.

Which properties does a block device report other than size?

Greetings
Marc

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