Re: 'ls /mnt/scratch/' freeze(deadlock?) when run xfstest(btrfs/232)

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2021/4/22 上午12:03, Filipe Manana wrote:
> On Wed, Apr 21, 2021 at 4:57 PM Wang Yugui <wangyugui@e16-tech.com> wrote:
>>
>> Hi,
>>
>>> That's the problem, qgroup flushing triggers writeback for an inode
>>> for which we have a page dirtied and locked.
>>> This should fix it:  https://pastebin.com/raw/U9GUZiEf
>>>
>>> Try it out and I'll write a changelog later.
>>> Thanks.
>>
>> we run xfstest on two server with this patch.
>> one passed the tests.
>> but one got a btrfs/232 error.
>>
>> btrfs/232 32s ... _check_btrfs_filesystem: filesystem on /dev/nvme0n1p1 is inconsistent
>> (see /usr/hpc-bio/xfstests/results//btrfs/232.full for details)
>> ...
>> [4/7] checking fs roots
>> root 5 inode 337 errors 400, nbytes wrong
>> ERROR: errors found in fs roots
>
> Ok, that's a different problem caused by something else.
> It's possible to be due to the recent refactorings for preparation to
> subpage block size.

This error looks exactly what I have seen during subpage development.
The subpage bug is caused by incorrect btrfs_invalidatepage() though,
and not yet merged into misc-next anyway.

I guess it's some error path not clearing extent states correctly, thus
leaving the inode nbytes accounting wrong.

BTW, the new @in_reclaim_context parameter for start_delalloc_inodes()
is already in misc-next:
commit 3d45f221ce627d13e2e6ef3274f06750c84a6542
Author: Filipe Manana <fdmanana@suse.com>
Date:   Wed Dec 2 11:55:58 2020 +0000

     btrfs: fix deadlock when cloning inline extent and low on free
metadata space

We only need to make btrfs_start_delalloc_snapshot() to accept the new
parameter and pass in_reclaim_context = true for qgroup.

Thanks,
Qu
>
> Will try to look into that later.
>
> Thanks.
>
>> ...
>>
>> Best Regards
>> Wang Yugui (wangyugui@e16-tech.com)
>> 2021/04/21
>>
>
>