Re: [PATCH] btrfs-progs: add verbose option to btrfs device scan

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

> On 16 Jul 2019, at 2:46 PM, Nikolay Borisov <nborisov@suse.com> wrote:
> 
> 
> 
> On 16.07.19 г. 4:26 ч., Qu Wenruo wrote:
>> 
>> 
>> On 2019/7/15 下午11:09, Nikolay Borisov wrote:
>>> 
>>> 
>>> On 15.07.19 г. 17:42 ч., Anand Jain wrote:
>>>> To help debug device scan issues, add verbose option to btrfs device scan.
>>>> 
>>>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>>> 
>>> I fail to see what this patch helps for. We get the path in case of
>>> errors, in case of success what good could the path be ?
>> 
>> AFAIK it would provide an easy way to debug blkid related bug.
>> 
>> E.g. scan only works on some devices and misses some devices.
> 
> In this case (and I already debugged one such case) it's invaluable to
> use LIBBLKID_DEBUG environment variable, the debug string added in this
> patch won't help in this particular case.
> 
> <snip>

Export LIBBLKID_DEBUG=all is good for debugging libblkid itself,
btrfs dev scan -v provides a confirmation on which devices
were scanned and their paths.

Thanks, Anand