btrfs check: extent buffer leak: start 30572544 len 16384

btrfs check: extent buffer leak: start 30572544 len 16384

[Christoph Anton Mitterer]

Hey.

On a freshly created, never mounted btrfs I get a new:
extent buffer leak: start 30572544 len 16384

with btrfs-progs 5.19:

# btrfs check --mode lowmem /dev/mapper/data-a-1 ; echo $?
Opening filesystem to check...
Checking filesystem on /dev/mapper/data-a-1
UUID: ff14e046-d72c-4671-b30a-6ec17c58a0f1
[1/7] checking root items
[2/7] checking extents
[3/7] checking free space tree
[4/7] checking fs roots
[5/7] checking only csums items (without verifying data)
[6/7] checking root refs done with fs roots in lowmem mode, skipping
[7/7] checking quota groups skipped (not enabled on this FS)
found 147456 bytes used, no error found
total csum bytes: 0
total tree bytes: 147456
total fs tree bytes: 32768
total extent tree bytes: 16384
btree space waste bytes: 140595
file data blocks allocated: 0
 referenced 0
extent buffer leak: start 30572544 len 16384
0
# btrfs check /dev/mapper/data-a-1 ; echo $?
Opening filesystem to check...
Checking filesystem on /dev/mapper/data-a-1
UUID: ff14e046-d72c-4671-b30a-6ec17c58a0f1
[1/7] checking root items
[2/7] checking extents
[3/7] checking free space tree
[4/7] checking fs roots
[5/7] checking only csums items (without verifying data)
[6/7] checking root refs
[7/7] checking quota groups skipped (not enabled on this FS)
found 147456 bytes used, no error found
total csum bytes: 0
total tree bytes: 147456
total fs tree bytes: 32768
total extent tree bytes: 16384
btree space waste bytes: 140595
file data blocks allocated: 0
 referenced 0
extent buffer leak: start 30572544 len 16384
0


Is that just some diagnostics or what does it mean? "leak" never sounds
so good ;-)

Thanks,
Chris.

Re: btrfs check: extent buffer leak: start 30572544 len 16384

[Christoph Anton Mitterer]

btw: This is on Linux 5.19.6, i.e. supposedly with the free-space-cache
v2 corruption fix.


But a freshly created fs with:
mkfs.btrfs -R ^free-space-tree

does *not* show the:
extent buffer leak: start 30687232 len 16384


Kinda loosing my trust in v2 space cache ;-)


Cheers,
Chris.

Re: btrfs check: extent buffer leak: start 30572544 len 16384

[Qu Wenruo]

On 2022/9/4 06:11, Christoph Anton Mitterer wrote:
> btw: This is on Linux 5.19.6, i.e. supposedly with the free-space-cache
> v2 corruption fix.
>
>
> But a freshly created fs with:
> mkfs.btrfs -R ^free-space-tree
>
> does *not* show the:
> extent buffer leak: start 30687232 len 16384
>
>
> Kinda loosing my trust in v2 space cache ;-)

Already known and fixed:
https://patchwork.kernel.org/project/linux-btrfs/patch/043f1db2c7548723eaff302ebba4183afb910830.1661835430.git.wqu@suse.com/

Thanks,
Qu

>
>
> Cheers,
> Chris.

Re: btrfs check: extent buffer leak: start 30572544 len 16384

[Christoph Anton Mitterer]

Hey Qu.

On Sun, 2022-09-04 at 06:58 +0800, Qu Wenruo wrote:
> Already known and fixed:
> https://patchwork.kernel.org/project/linux-btrfs/patch/043f1db2c7548723eaff302ebba4183afb910830.1661835430.git.wqu@suse.com/

As far as I understand this means that there's only an error in the
check,... but the filesystem itself is perfectly fine?


Thanks,
Chris.

Re: btrfs check: extent buffer leak: start 30572544 len 16384

[Qu Wenruo]

On 2022/9/4 07:00, Christoph Anton Mitterer wrote:
> Hey Qu.
>
> On Sun, 2022-09-04 at 06:58 +0800, Qu Wenruo wrote:
>> Already known and fixed:
>> https://patchwork.kernel.org/project/linux-btrfs/patch/043f1db2c7548723eaff302ebba4183afb910830.1661835430.git.wqu@suse.com/
>
> As far as I understand this means that there's only an error in the
> check,... but the filesystem itself is perfectly fine?

Yep.

All eb leakage is only a bug of progs, nothing to worry about with the
filesystem.

Thanks,
Qu

>
>
> Thanks,
> Chris.

Re: btrfs check: extent buffer leak: start 30572544 len 16384

[Christoph Anton Mitterer]

Google used to perform better ... I actually searched for the message,
but it only brought up some quite old patches:
https://patchwork.kernel.org/project/linux-btrfs/patch/1420444575-23259-1-git-send-email-quwenruo@cn.fujitsu.com/
https://patchwork.kernel.org/project/linux-btrfs/patch/aa032e11aa2b8667a28a93b90691d6f790711c62.1612449293.git.fdmanana@suse.com/#23954447


On Sun, 2022-09-04 at 07:01 +0800, Qu Wenruo wrote:
> Yep.

As always, thanks :-)


Cheers,
Chris.

Re: btrfs check: extent buffer leak: start 30572544 len 16384

[David Sterba]

On Sun, Sep 04, 2022 at 01:06:12AM +0200, Christoph Anton Mitterer wrote:
> Google used to perform better ... I actually searched for the message,
> but it only brought up some quite old patches:
> https://patchwork.kernel.org/project/linux-btrfs/patch/1420444575-23259-1-git-send-email-quwenruo@cn.fujitsu.com/
> https://patchwork.kernel.org/project/linux-btrfs/patch/aa032e11aa2b8667a28a93b90691d6f790711c62.1612449293.git.fdmanana@suse.com/#23954447
> 
> 
> On Sun, 2022-09-04 at 07:01 +0800, Qu Wenruo wrote:
> > Yep.
> 
> As always, thanks :-)

I'll do a btrfs-progs bugfix release soonish, including this fix.