Re: Simple quota unsafe? RIP: 0010:__btrfs_free_extent.isra.0+0xc41/0x1020 [btrfs] / do_free_extent_accounting:2999: errno=-2 No such entry

[Marc MERLIN <marc_btrfs@merlins.org>]

On Wed, Apr 15, 2026 at 03:36:29PM -0700, Boris Burkov wrote:
> On Wed, Apr 15, 2026 at 01:22:42PM -0700, Marc MERLIN wrote:
> > On Wed, Apr 15, 2026 at 11:44:27AM -0700, Boris Burkov wrote:
> > > For a giant fs where we don't want to dump all the metadata or it would
> > > be difficult to share the resulting gigabytes of text, I would still get
> > > quite a bit of benefit from:
> > > 
> > > btrfs inspect-internal dump-tree -t 2 /dev/tst/lol
> > 
> > 1.2G    /tmp/tree2.txt
> > 65M     /tmp/tree2.txt.xz
> > do you want it?
> 
> Yes, please!
 
https://marc.merlins.org/tmp/tree2.txt.xz
please tell me when I can delete.

> > > btrfs inspect-internal dump-tree -t 8 /dev/tst/lol
> > 
> > btrfs-progs v6.14
> > total bytes 4074040004608
> > bytes used 2417457491968
> > uuid 49741c78-3949-4d7d-b77a-160ce071dee0
> > merlin:/mnt/btrfs_pool3# 
> 
> So no output? That is surprising. Did you already disable quotas on this
> filesystem?
 
Ah, sorry, yes. First rule of sysadmining: after an unexplained crash:
revert the last thing(s) you did.  2 crashes in 3 days on systems that
were stable for years right after I turned on simple quotas and block-group-tree
could not be a coincidence.
Thankfully the laptop FS was not put into an unusable state and I was
able to get it back online quickly. As soon as I did, turned quotas off.

Since then I have upgraded the laptop to 6.19.11 and turned squotas back
on on that single filesystem.

Sorry if I removed evidence that could have helped. It's still on
moremagic, the rPi, since I could never remount read/write and turn off
quotas. Obviously I can do dump trees on it (please provide exact
commands you'd like so I don't mess them up)
I think there is also a way to backup the entire filesystem structure,
mangle the filenames, and omit the data to alllow a copy that is much
smaller and restore in a VM with spare blocks to emulate the FS without
needing 22TB

Let me know if either helps

Thanks,
Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
 
Home page: http://marc.merlins.org/                       | PGP 7F55D5F27AAF9D08