Re: Occasionally mkfs.reiser4 creates a file system without a UUID

[Edward Shishkin <edward.shishkin@gmail.com>]

On 03/15/2021 11:20 PM, Mike Fleetwood wrote:
> On Sat, 13 Mar 2021 at 14:28, Edward Shishkin <edward.shishkin@gmail.com> wrote:
>>
>> On 03/13/2021 12:37 PM, Edward Shishkin wrote:
>>> On 03/12/2021 08:36 PM, Mike Fleetwood wrote:
>>>> Hi,
>>>>
>>>> Occasionally mkfs.reiser4 creates a file system without a UUID,
>>>> debugfs.reiser4 reports UUID as '<none>'.  This is being detected in
>>>> GParted's file system interface CI tests [1] which exercises the resier4
>>>> commands.
>>>>
>>>> In a Ubuntu 20.04 LTS VM with both resier4progs-1.2.1-1 package and
>>>> current code from GIT, the fault can easily be replicated like this:
>>>>
>>>> truncate -s 256M test.img
>>>> i=1
>>>> while :
>>>> do
>>>>     mkfs.reiser4 --force --yes --label '' test.img
>>>>     line=`debugfs.reiser4 test.img 2> /dev/null | egrep '^uuid:'`
>>>>     echo "[$i] $line"
>>>>     ((i++))
>>>>     echo "$line" | grep -q '<none>' && break
>>>> done
>>>>
>>>> Output fragment:
>>>> [1] uuid:        17073919-e41d-4892-9b22-4294d1544c4a
>>>> [2] uuid:        af2821de-ea85-4f20-9621-4fbd128b3fb8
>>>> [3] uuid:        c0fb805b-e224-4695-a504-d87460d158ae
>>>> ...
>>>> [35] uuid:        d604794d-097f-4810-bbb3-01a1518f3ef1
>>>> [36] uuid:        9634100c-1f98-42b3-a684-c9df77ab54e2
>>>> [37] uuid:        <none>
>>>>
>>>> Performing the same test with resierfs and ext4 runs for many hours
>>>> doing 100,000s of iterations without issue.
>>>>
>>>
>>>
>>> It seems that debugfs.reiser4 prints uuid incorrectly: it assumes that
>>> binary uuid can't contain '\0' symbols, which apparently is wrong.
>>> Thus, if the first uuid's symbol is '\0', debugfs thinks that uuid is
>>> not set and prints "none" ;)
>>>
>>> I'll try to prepare a fixup a bit later.
>>> Special thanks for the nice testing script!
>>>
>>
>>
>> Here is the fixup:
>> https://github.com/edward6/reiser4progs/commit/4802cdb18ae03031d0e51a58b6655f3b99021ec2
> 
> Your fix to debugfs.reiser4 allows for printing of UUIDs correctly.
> Here's my pull request to fix mkfs.reiser4 for not writing UUIDs
> correctly in the first place.
> https://github.com/edward6/reiser4progs/pull/1


Mike, thanks a lot!

For me personally, this is the worst kind of bugs (hardly fishable by
code reviews plus not always reproducible).

I cherry pick-ed your commit also for the parallel branch "format41":
https://github.com/edward6/reiser4progs/commit/01a5e0e41ec8d5147091d44e902d60f61c336f30

Edward.