[CRIU] [PATCH] sk-unix: set mntinfo

[Pavel Emelyanov]

On 09/14/2016 12:13 AM, Christian Brauner wrote:
> On Tue, Sep 13, 2016 at 10:51:04PM +0200, Christian Brauner wrote:
>> On Tue, Sep 13, 2016 at 05:53:59PM +0300, Pavel Emelyanov wrote:
>>> On 09/07/2016 05:29 PM, Christian Brauner wrote:
>>>> phys_stat_resolve() call mount_resolve_path() which requires that mntinfo_tree
>>>> in the ns_id struct is initialized. This is a problem we observed with sockets
>>>> on btrfs volumes:
>>>
>>> Sorry for the late response. See my comment inline.
>>>
>>>> Signed-off-by: Christian Brauner <christian.brauner at canonical.com>
>>>> ---
>>>>  criu/sk-unix.c | 1 +
>>>>  1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/criu/sk-unix.c b/criu/sk-unix.c
>>>> index 99f0b08..a199ca4 100644
>>>> --- a/criu/sk-unix.c
>>>> +++ b/criu/sk-unix.c
>>>> @@ -525,6 +525,7 @@ static int unix_process_name(struct unix_sk_desc *d, const struct unix_diag_msg
>>>>  			ret = -ENOENT;
>>>>  			goto out;
>>>>  		}
>>>> +		ns->mnt.mntinfo_tree = mntinfo;
>>>
>>> I guess that's too late for this assignment. Since this is dump time, then
>>> ns->mnt.mntinfo_tree should have been initialized in collect_mntns() or
>>> nearby.
>>
>> It is in collect_mntinfo() but it seems calling lookup_ns_by_id() in
>> unix_process_name() does return an ns_id but ns.mnt->mntinfo_tree is not
>> initialized. Is mntinfo a global that is identical for all ns_ids in the linked
>> list? If not how should they be initialized?
> 
> Scratch that, collect_mntinfo() is per namespace. The question is when to call
> it. One option is that as soon as you add a new ns_id you call collect_mntinfo()
> or you call it *first* when you need it, i.e. you check whether mntinfo_tree ==
> NULL and if so call collect_mntinfo() on the corresponding ns_id.

Actually collect_mntinfo() is called for every namespace found already. Can you
trace back why the ns you see isn't yet collect_mntinfo()-ed at the time the
unix_process_name() is?

-- Pavel