[CRIU] [PATCH v2 3/5] mount: save ext_real_root for external mounts

[Pavel Tikhomirov]

On 03/20/2017 10:03 PM, Andrew Vagin wrote:
> On Mon, Mar 20, 2017 at 12:45:42PM +0300, Pavel Tikhomirov wrote:
>> need it to check if we can bindmount from external mount
>>
>> https://jira.sw.ru/browse/PSBM-46753
>>
>> v2: s/real_root/ext_real_root/
>> Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
>> ---
>>  criu/mount.c     | 3 ++-
>>  images/mnt.proto | 1 +
>>  2 files changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/criu/mount.c b/criu/mount.c
>> index 6e5a4c6..ef5c1ec 100644
>> --- a/criu/mount.c
>> +++ b/criu/mount.c
>> @@ -1335,6 +1335,7 @@ static int dump_one_mountpoint(struct mount_info *pm, struct cr_img *img)
>>  		 * for reverse mapping details.
>>  		 */
>>  		me.root	= pm->external;
>> +		me.ext_real_root = pm->root;
>>  		me.has_ext_mount = true;
>>  		me.ext_mount = true;
>>  	} else
>> @@ -2445,7 +2446,7 @@ static int get_mp_root(MntEntry *me, struct mount_info *mi)
>>  {
>>  	char *ext = NULL;
>>
>> -	mi->root = xstrdup(me->root);
>> +	mi->root = xstrdup(me->ext_real_root ? : me->root);
>>  	if (!mi->root)
>>  		return -1;
>>
>> diff --git a/images/mnt.proto b/images/mnt.proto
>> index 50cd8af..3294319 100644
>> --- a/images/mnt.proto
>> +++ b/images/mnt.proto
>> @@ -53,4 +53,5 @@ message mnt_entry {
>>
>>  	optional bool		deleted			= 16;
>>  	optional uint32		sb_flags		= 17 [(criu).hex = true];
>> +	optional string		ext_real_root		= 18;
>
> We need a comment here what this means. What do you think if we add
> ext_key instead of ext_real_root, for me it looks more understandable.

If we use me->root for real root, and me->ext_key for the key of the 
mount, that would surely break backward compatibility, as old criu will 
still want the key in me->root.

Thus we should leave the key of the mount in me->root. And naming the 
field in which I want to save the real root(path in the file system to 
the root of these mount) as me->ext_key is counterintuitive to me.

>>  }
>> --
>> 2.9.3
>>

-- 
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.