Re: [xfstests/generic/081] Kernel panic with reg40 plugin and R4-for-4.1.5.patch

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

On 09/10/2015 09:42 PM, Dušan Čolić wrote:
> On Thu, Sep 10, 2015 at 9:20 PM, Edward Shishkin
> <edward.shishkin@gmail.com> wrote:
>> Actually, this is not a regression.
>> The attached patch prevents the panic.
>> By default on IO errors reiser4 partition will be remounted as "readonly".
>>
>> No ideas why accessing /dev/dm-X causes IO error.
>> Reiser4 is not the culprit ;) You can narrow down this, if interesting.
>> I think that something is wrong with LVM settings...
>>
> I looked more into this: This test fills up dm snapshot (writes 5MB to
> 4MB snapshot) so we get IO error because it's full.


IO error because of no space - it is very strange,
especially when reading the device (as in my case):

# dd if=/dev/dm-3 of=/dev/null bs=4096 count=1


>   It doesn't trigger
> on ccreg40 because ccreg40 compresses data so 5MB of compressible data
> < 4MB space ;)
> xfstests uses compressible data for disk full tests so on ccreg40 they
> give false positive. Are ccreg40 and reg40 code paths for disk full
> situation the same?
> I'll look into fixing xfstetsts.
>> Thanks,
>> Edward.
>>
>>
>>
>> On 09/04/2015 09:35 AM, Dušan Čolić wrote:
>>> Kernel: 4.1.6
>>> R4 patch: 4.1.5
>>> Test: xfstests/generic/081 "Test I/O error path by fully filling an dm
>>> snapshot."
>>>
>>> Test passes cleanly with ccreg40 but kernel panics with reg40 plugin.
>>> Picture of the panic, as I had no other means of capturing it, is in
>>> attachment.
>>>
>>> xfstests local.config section:
>>>
>>> [r4Hybrid]
>>> MKFS_OPTIONS="-o create=reg40"
>>> MOUNT_OPTIONS="-o noatime"
>>>
>>> Have a nice day.
>>>
>>> Dushan
>>

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