Re: [PATCH] btrfs: device stat, log when zeroed assist audit

[Anand Jain <anand.jain@oracle.com>]

On 1/10/20 11:07 PM, Josef Bacik wrote:
> On 1/9/20 11:26 PM, Anand Jain wrote:
>> We had a report indicating that some read errors aren't reported by
>> the device stats in the userland. It is important to have the errors
>> reported in the device stat as user land scripts might depend on it to
>> take the reasonable corrective actions. But to debug these issue we need
>> to be really sure that request to reset the device stat did not come
>> from the userland itself. So log an info message when device error reset
>> happens.
>>
>> For example:
>>   BTRFS info (device sdc): device stats zeroed by btrfs (9223)
>>
>> Reported-by: philip@philip-seeger.de
>> Link: https://www.spinics.net/lists/linux-btrfs/msg96528.html
>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>> ---
>>   BTRFS info (device sdc): device stats zeroed by btrfs (9223)
>> The last words are name and pid of the process, unfortunately it came out
>> as 'by btrfs'. At some point if there is a python and lib to reset it
>> would change, otherwise its going to be 'by btrfs', I am ok with it,
>> if otherwise please suggest the alternative.
> 
> I think name(pid) makes sense, similar to what drop_caches does
> 
> pr_info("%s (%d): drop_caches: %d\n",
>      current->comm, task_pid_nr(current),

There is a small deviation to what we already have in
device_list_add(), name (pid) is at the end the log message..

------
                         pr_info(
         "BTRFS: device label %s devid %llu transid %llu %s scanned by 
%s (%d)\n",
                                 disk_super->label, devid, 
found_transid, path,
                                 current->comm, task_pid_nr(current));
--------

I am not sure. Can David can tweak during merge ?

Thanks, Anand

> Thanks,
> 
> Josef