[CRIU] [PATCH 2/4] mount: add support for external block devices

[Pavel Emelyanov]

On 04/20/2016 08:04 AM, Pavel Emelyanov wrote:
> On 04/19/2016 05:59 PM, Andrew Vagin wrote:
>> On Tue, Apr 19, 2016 at 01:19:48PM +0300, Pavel Emelyanov wrote:
>>> On 04/19/2016 03:44 AM, Andrew Vagin wrote:
>>>> On Mon, Apr 18, 2016 at 07:36:52PM +0300, Pavel Emelyanov wrote:
>>>>> On 04/15/2016 01:19 AM, Andrey Vagin wrote:
>>>>>> From: Andrew Vagin <avagin at virtuozzo.com>
>>>>>>
>>>>>> It works like enable-fs, in this case we allow to mount a specified block device.
>>>>>>
>>>>>> Options:
>>>>>> dump:		--external mnt[MAJOR:MINOR]
>>>>>> restore:	--mnt-ext-map mnt[MAJOR:MINOR]:DEVPATH
>>>>>
>>>>> We don't have --mnt-ext-map option :\
>>>>
>>>> I mean --ext-mount-map
>>>>>
>>>>> Please, explain what the option arguments mean.
>>>
>>> Please, explain what the option arguments mean.
>>
>> We save major and minor numbers for each mount, then on restore
>> we can say that DEVPATH should be mounted instead of the origin device.
> 
> OK. It looks like you're trying to screw up the --ext-mount-map option.
> Can we make the --external one work on both sides instead?

The --ext-mount-map on dump means:
	take the mountpoint KEY and save VAL into image
on restore:
	take the mountpoint KEY from image and mount it from VAL on host

I think I'm OK with making this option work for fsroot mounts too, but
then, to obey the above definition, the --ext-mount-map on dump should
enable unsupported fsroot mount and on restore tun the source (as it is
in the patch).

-- Pavel