Re: [PATCH 00/12] btrfs: remap tree

[Mark Harmstone <maharmstone@meta.com>]

Thanks Qu.

On 11/6/25 00:56, Qu Wenruo wrote:
> 在 2025/6/11 00:01, Mark Harmstone 写道:
>> On 5/6/25 17:23, Mark Harmstone wrote:
>>> * Some test failures: btrfs/156, btrfs/170, btrfs/226, btrfs/250
>>
>> These all turned out to be spurious.
>>
>> btrfs/226 is broken for me on the btrfs/for-next branch that I based
>> these on (254ae2606b258a63b5063bed03bb4cf87a688502)
> 
> You may need to update fstests, as a recent kernel change requires 
> nodatasum for NOWAIT.
> 
> And fstest commit 7e92cb991b0b ("fstests: btrfs/226: use nodatasum mount 
> option to prevent false alerts") updated the test case to handle the 
> kernel change.

Makes sense, thank you.

>> btrfs/156, btrfs/170, and btrfs/250 all involve creating small
>> filesystems, which are then ENOSPCing because of the extra REMAP chunk.
> 
> I do not have a good idea how to handle those cases.
> 
> E.g, the test case btrfs/156 is creating a 1G fs, although small it 
> should still be fine for most cases.
> 
> If even a single 32MiB remap chunk is causing ENOSPC, it may indicate 
> more ENOSPC in the real world.

Probably 8MB actually, as IIRC that's the chunk size that mkfs uses for 
everything. It'd be 32MB the second and subsequent times round.

I'll investigate the tests properly, but I'm fairly sure they're not 
diagnosing a problem with this particular patchset.

Mark