[CFT][PATCH] mnt: Implicitly add MNT_NODEV on remount when it was implicitly added by mount

[Eric W. Biederman]

Richard Weinberger <richard at nod.at> writes:

> Am 30.11.2014 um 16:37 schrieb Andy Lutomirski:
>> On Sun, Nov 30, 2014 at 7:16 AM, Richard Weinberger <richard at nod.at> wrote:
>>> Am 30.11.2014 um 16:00 schrieb Andy Lutomirski:
>>>> On Sun, Nov 30, 2014 at 6:58 AM, Richard Weinberger <richard at nod.at> wrote:
>>>>> Eric,
>>>>>
>>>>> Am 30.11.2014 um 00:05 schrieb Eric W. Biederman:
>>>>>>
>>>>>> Now that remount is properly enforcing the rule that you can't remove
>>>>>> nodev at least sandstorm.io is breaking when performing a remount.
>>>>>>
>>>>>> It turns out that there is an easy intuitive solution implicitly
>>>>>> add nodev on remount when nodev was implicitly added on mount.
>>>>>
>>>>> Is this patch supposed to unbreak libvirt-lxc?
>>>>> At least 1.2.9 is still broken.
>>>>>
>>>>
>>>> Either this patch or my variant of it fixes the libvirt-lxc breakage
>>>> that I understand, but IIRC there was some other issue that none of us
>>>> figured out at K-S.
>>>
>>> Currently it fails here:
>>> 2014-11-25 22:36:45.295+0000: 1: debug : virFileMakePathHelper:2436 : path=/proc mode=0777
>>> 2014-11-25 22:36:45.295+0000: 1: debug : lxcContainerMountBasicFS:918 : Mount proc on /proc type=proc flags=e
>>> 2014-11-25 22:36:45.296+0000: 1: debug : lxcContainerMountBasicFS:873 : Processing /proc/sys -> /proc/sys
>>> 2014-11-25 22:36:45.296+0000: 1: debug : virFileMakePathHelper:2436 : path=/proc/sys mode=0777
>>> 2014-11-25 22:36:45.296+0000: 1: debug : lxcContainerMountBasicFS:918 : Mount /proc/sys on /proc/sys type=(null) flags=1000
>>> 2014-11-25 22:36:45.296+0000: 1: error : lxcContainerMountBasicFS:933 : Failed to re-mount /proc/sys on /proc/sys flags=1021: Operation not permitted
>> 
>> Any chance you can test that with Eric's patch or mine [1] applied?
>> If that doesn't work, can you try to catch the failure with strace?
>
> With your patch applied on top of Linus's tree as of today libvirt-lxc works fine again. :)

*Scratches head*

Did you really have my latest patch applied?

Andy's patch implies a change of policy that I really don't want to
deploy as a bug fix.

Eric