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

[Boris Burkov <boris@bur.io>]

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!

> > and
> > 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?

> > that is relatively less important. If the extent tree dumps way too
> > much, then doing a grep -C 50 for 15506102321152 would likely be enough
> > to show us the relevant backrefs.
> 
> No match:
> merlin:/mnt/btrfs_pool3# btrfs inspect-internal dump-tree -t 2 /dev/mapper/pool3 | grep -50 15506102321152
> merlin:/mnt/btrfs_pool3#
> 
> Anything else I can do?
> 

This is making me suspect *not* quotas now. That is the extent the mount
failed on. So it does seem to be the extent which is missing not the
qgroup.

However, it is possible that whatever has happened to the system since
the original abort / mount attempts is distorting our observations.

> > If there is no rush to wipe it, then let's keep it around until I rule
> > out whether a repair patch makes sense? Sorry if I misunderstood the
> > state. If there *is* a rush to wipe it, then let's confirm we got what
> > we needed out of tree dumping first, if possible.
> 
> At this point, I can wait.
> 
> 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