[CRIU] [PATCH v5 5/5] mount: Restore binfmt_misc content in case of missing mount

[Pavel Emelyanov]

On 08/15/2016 11:57 AM, Kirill Tkhai wrote:
> 
> 
> On 05.08.2016 18:43, Pavel Emelyanov wrote:
>> On 08/04/2016 04:49 PM, Kirill Tkhai wrote:
>>> In case of mount image is not containing binfmt_misc mountpoint,
>>> add temporary mountpoint to mount tree and try to restore
>>> binfmt_misc content in ordinary way. Then, umount temporary mountpoint.
>>>
>>> v4: New
>>> v5: Check for opts.has_binfmt_misc to determine if image presents
>>>
>>> Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
>>> ---
>>>  criu/mount.c |   19 ++++++++++++++++++-
>>>  1 file changed, 18 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/criu/mount.c b/criu/mount.c
>>> index 926817a..964dbbc 100644
>>> --- a/criu/mount.c
>>> +++ b/criu/mount.c
>>> @@ -2451,6 +2451,15 @@ static int do_new_mount(struct mount_info *mi)
>>>  	if (tp->restore && tp->restore(mi))
>>>  		return -1;
>>>  
>>> +	if (!mi->mnt_id) {
>>> +		/* C-r time mountpoint, umount it */
>>> +		if (umount(mi->mountpoint) < 0) {
>>> +			pr_perror("Can't umount %s\n", mi->mountpoint);
>>> +			return -1;
>>> +		}
>>> +		goto out;
>>> +	}
>>> +
>>>  	if (remount_ro && mount(NULL, mi->mountpoint, tp->name,
>>>  				     MS_REMOUNT | MS_RDONLY, NULL)) {
>>>  		pr_perror("Unable to apply mount options");
>>> @@ -2470,7 +2479,7 @@ static int do_new_mount(struct mount_info *mi)
>>>  	BUG_ON(mi->master_id);
>>>  	if (restore_shared_options(mi, !mi->shared_id, mi->shared_id, 0))
>>>  		return -1;
>>> -
>>> +out:
>>>  	mi->mounted = true;
>>>  
>>>  	return 0;
>>> @@ -3339,6 +3348,7 @@ static int populate_mnt_ns(void)
>>>  	struct mount_info *pms;
>>>  	struct ns_id *nsid;
>>>  	struct mount_info *roots_mp = NULL;
>>> +	struct stat st;
>>>  	int ret;
>>>  
>>>  	if (mnt_roots) {
>>> @@ -3355,6 +3365,13 @@ static int populate_mnt_ns(void)
>>>  	if (!pms)
>>>  		return -1;
>>>  
>>> +	if (!opts.has_binfmt_misc && stat_image(CR_FD_BINFMT_MISC, &st, 0) == 0) {
>>
>> This should be the other way. In cr-restore.c we have an array of so called cinfos -- these
>> are images that should be pre-loaded during restore. So it's better to add new-style binfmt
>> cinfo and read_mnt_ns_img should check cinfo->flags for COLLECT_HAPPENED (not 100% sure it
>> handles empty images correctly, plz, check) and add cr-time mount if it had.
> 
> You had suggested to dump any binfmt_misc content (belonging to a mount point or not)
> to the file of the same name. So, the new suggestion doesn't work.

Why?

> The code, I did, populates opts.has_binfmt_misc in dependence of belonging mountpoint exists or not.
> Your new suggestion isn't able to handle this.

Why? The cinfo collection code calls callback so you can set opts.whatver there.

>> -- Pavel
>>
>>> +		/* Add to mount tree. Generic code will mount it later */
>>> +		ret = add_cr_time_mount(pms, "binfmt_misc", BINFMT_MISC_HOME, 0);
>>> +		if (ret)
>>> +			return -1;
>>> +	}
>>> +
>>>  	if (resolve_shared_mounts(mntinfo, pms->master_id))
>>>  		return -1;
>>>  
>>>
>>> _______________________________________________
>>> CRIU mailing list
>>> CRIU at openvz.org
>>> https://lists.openvz.org/mailman/listinfo/criu
>>> .
>>>
>>
> .
>