On 2019/4/6 上午8:22, Qu Wenruo wrote:
> 
> 
> On 2019/4/5 下午11:49, David Sterba wrote:
>> On Thu, Apr 04, 2019 at 11:47:06AM +0800, Qu Wenruo wrote:
>>> This patchset can be fetched from github:
>>> https://github.com/adam900710/linux/tree/tree_checker_testing
>>>
>>> Which is based on misc-next, with the following commit as HEAD:
>>> commit 56d46f96de92ec69963acb7b1d9aed83d2a56a7b (david/misc-next-with-write-checks, david/misc-next)
>>> Author: Nikolay Borisov <nborisov@suse.com>
>>> Date:   Wed Mar 27 14:24:18 2019 +0200
>>>
>>>     btrfs: Switch btrfs_trim_free_extents to find_first_clear_extent_bit
>>>
>>> These two patches changes the behavior of write time tree-checker, where
>>> the initial patches didn't check the content of the leaf, leaving memory
>>> bit flipping possible to sneak in.
>>>
>>> This patchset also introduces a new optimization, where original empty
>>> leaf owner check can be pretty expensive and cause false alerts for
>>> write time tree checker.
>>> With this new optimization, write time tree checker can reuse the
>>> existing btrfs_check_leaf_full().
>>
>> This on top of misc-next throws 6 'write time' errors:
>>
>> btrfs/101               [14:00:24][ 3963.736352] run fstests btrfs/101 at 2019-04-05 14:00:24
>> [ 3970.417649] BTRFS error (device vdc): block=2446344192 write time tree block corruption detected
> 
> In my case, these tests just pass, so I haven't checked the dmesg.

Oh, those tests passes because of a bug in mainline.

6dc4f100c175 ("block: allow bio_for_each_segment_all() to iterate over
multi-page bvec") prevents us from breaking bio_for_each_segment_all()
loop, thus not triggering transaction abort.

A nice finding digging into the report.

Thanks,
Qu

> 
> But indeed I can reproduce the same dmesg line.
> 
> Before removing the device, btrfs will use btrfs_shrink_device(new_size
> = 0) to remove all data from that device.
> 
> And that will cause on-disk total_bytes to be 0, triggering the bug.
> 
> So indeed the behavior is different between read and write time.
> 
> I'll check how to do it correctly.
> 
> Thanks,
> Qu
> 
>>
>> btrfs/151               [14:06:52][ 4351.133395] run fstests btrfs/151 at 2019-04-05 14:06:52
>> [ 4351.659771] BTRFS error (device vdb): block=570572800 write time tree block corruption detected
>>
>> btrfs/164               [14:07:19][ 4378.349990] run fstests btrfs/164 at 2019-04-05 14:07:19
>> [ 4380.645918] BTRFS error (device vdb): block=2479882240 write time tree block corruption detected
>>
>> btrfs/176               [14:07:39][ 4398.493736] run fstests btrfs/176 at 2019-04-05 14:07:39
>> [ 4399.186203] BTRFS error (device vdb): block=22036480 write time tree block corruption detected
>> [ 4399.302700] BTRFS error (device vdb): block=1372585984 write time tree block corruption detected
>>
>> btrfs/184               [14:10:13][ 4552.496289] run fstests btrfs/184 at 2019-04-05 14:10:13
>> [ 4553.292780] BTRFS error (device vdb): block=4602216448 write time tree block corruption detected
>>
>> Have you seen the errors during your testing?
>>
>