Re: read time tree block corruption detected

["Gervais, Francois" <FGervais@distech-controls.com>]

> On 2021/4/19 下午10:56, Gervais, Francois wrote:
>>> My bad, wrong number.
>>>
>>> The correct number command is:
>>> # btrfs ins dump-tree -b 790151168 /dev/loop0p3
>>
>>
>> root@debug:~# btrfs ins dump-tree -b 790151168 /dev/loop0p3
>> btrfs-progs v5.7
> [...]
>>        item 4 key (5007 INODE_ITEM 0) itemoff 15760 itemsize 160
>>                generation 294 transid 219603 size 0 nbytes 18446462598731726987
> 
> The nbytes looks very strange.
> 
> It's 0x0xfffeffffffef008b, which definitely looks aweful for an empty inode.
> 
>>                block group 0 mode 100600 links 1 uid 1000 gid 1000 rdev 0
>>                sequence 476091 flags 0x0(none)
>>                atime 1610373772.750632843 (2021-01-11 14:02:52)
>>                ctime 1617477826.205928110 (2021-04-03 19:23:46)
>>                mtime 1617477826.205928110 (2021-04-03 19:23:46)
>>                otime 0.0 (1970-01-01 00:00:00)
>>        item 5 key (5007 INODE_REF 4727) itemoff 15732 itemsize 28
>>                index 0 namelen 0 name:
>>                index 0 namelen 0 name:
>>                index 0 namelen 294 name:
> 
> Definitely corrupted. I'm afraid tree-checker is correct.
> 
> The log tree is corrupted.
> And the check to detect such corrupted inode ref is only introduced in
> v5.5 kernel, no wonder v5.4 kernel didn't catch it at runtime.

Would detecting it at runtime with a newer kernel have helped in any way with
the corruption?

> 
> I don't have any idea why this could happen, as it doesn't look like an
> obvious memory flip.

The test engineer says that the last thing he did was remove power from the
device.

Could power loss be the cause of this issue?

> 
> Maybe Filipe could have some clue on this?
> 
> Thanks,
> Qu
> 
>>        item 6 key (5041 INODE_ITEM 0) itemoff 15572 itemsize 160
>>                generation 295 transid 219603 size 4096 nbytes 4096
>>                block group 0 mode 100600 links 1 uid 1000 gid 1000 rdev 0
>>                sequence 321954 flags 0x0(none)
>>                atime 1610373832.763235044 (2021-01-11 14:03:52)
>>                ctime 1617477815.541863825 (2021-04-03 19:23:35)
>>                mtime 1617477815.541863825 (2021-04-03 19:23:35)
>>                otime 0.0 (1970-01-01 00:00:00)
>>        item 7 key (5041 INODE_REF 4727) itemoff 15544 itemsize 28
>>                index 12 namelen 18 name: health_metrics.txt
>>        item 8 key (5041 EXTENT_DATA 0) itemoff 15491 itemsize 53
>>                generation 219603 type 1 (regular)
>>                extent data disk byte 12746752 nr 4096
>>                extent data offset 0 nr 4096 ram 4096
>>                extent compression 0 (none)
>>        item 9 key (EXTENT_CSUM EXTENT_CSUM 12746752) itemoff 15487 itemsize 4
>>                range start 12746752 end 12750848 length 4096
>>