[CRIU] [PATCH v5 05/11] files: Add fd_open_state::finalize method()

[Pavel Emelyanov]

On 07/12/2016 10:40 AM, Kirill Tkhai wrote:
> 
> 
> On 12.07.2016 10:22, Kirill Tkhai wrote:
>>
>>
>> On 04.07.2016 20:28, Pavel Emelyanov wrote:
>>> On 06/28/2016 03:59 PM, Kirill Tkhai wrote:
>>>> On 28.06.2016 15:28, Pavel Emelyanov wrote:
>>>>> On 06/16/2016 04:53 PM, Kirill Tkhai wrote:
>>>>>> Add a method, which allows to close temporary files,
>>>>>> used on restore stage. This will be used in next patches.
>>>>>>
>>>>>> v5: New
>>>>>>
>>>>>> Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
>>>>>> ---
>>>>>>  criu/files.c         |    9 +++++++++
>>>>>>  criu/include/files.h |    3 +++
>>>>>>  2 files changed, 12 insertions(+)
>>>>>>
>>>>>> diff --git a/criu/files.c b/criu/files.c
>>>>>> index b9fdbdc..036e054 100644
>>>>>> --- a/criu/files.c
>>>>>> +++ b/criu/files.c
>>>>>> @@ -676,6 +676,7 @@ static int collect_fd(int pid, FdinfoEntry *e, struct rst_info *rst_info)
>>>>>>  	futex_init(&new_le->real_pid);
>>>>>>  	new_le->pid = pid;
>>>>>>  	new_le->fe = e;
>>>>>> +	new_le->flags = 0;
>>>>>>  
>>>>>>  	fdesc = find_file_desc(e);
>>>>>>  	if (fdesc == NULL) {
>>>>>> @@ -854,12 +855,14 @@ static int open_transport_fd(int pid, struct fdinfo_list_entry *fle);
>>>>>>  static int open_fd(int pid, struct fdinfo_list_entry *fle);
>>>>>>  static int receive_fd(int pid, struct fdinfo_list_entry *fle);
>>>>>>  static int post_open_fd(int pid, struct fdinfo_list_entry *fle);
>>>>>> +static int finalize_fd(int pid, struct fdinfo_list_entry *fle);
>>>>>>  
>>>>>>  static struct fd_open_state states[] = {
>>>>>>  	{ "prepare",		open_transport_fd,	true,},
>>>>>>  	{ "create",		open_fd,		true,},
>>>>>>  	{ "receive",		receive_fd,		false,},
>>>>>>  	{ "post_create",	post_open_fd,		false,},
>>>>>> +	{ "finalize",		finalize_fd,		true,},
>>>>>>  };
>>>>>>  
>>>>>>  #define want_recv_stage()	do { states[2].required = true; } while (0)
>>>>>> @@ -993,6 +996,12 @@ static int post_open_fd(int pid, struct fdinfo_list_entry *fle)
>>>>>>  	return d->ops->post_open(d, fle->fe->fd);
>>>>>>  }
>>>>>>  
>>>>>> +static int finalize_fd(int pid, struct fdinfo_list_entry *fle)
>>>>>> +{
>>>>>> +	if (fle->flags & FD_LE_GHOST)
>>>>>> +		close(fle->fe->fd);
>>>>>
>>>>> Hm... Why can't we just do this in post_open_fd-s?
>>>>
>>>> Promiscous queues are restored in post-open stage.
>>>> All ghost fle must be alive at this moment.
>>>
>>> OK, so we call post_open callbacks and close these guys right after it. No?
>>
>> Sure.
> 
> We have ghost SocketA and alive SocketB. SocketB needs SocketA to restore its queue.
> The first socket in file list is SocketA, the second is SocketB.
> 
> So, when we call close() in SocketA post_open(), SocketB can't use it in its post_open()
> and can't restore its queue.

I see two solutions:

1. So put the socketB before socketA in the list
2. After the ->post open stage is complete walk the fdlist again and
   close the ghost ones WITHOUT the explicit "finalize" stage.

>>>>>> +	return 0;
>>>>>> +}
>>>>>>  
>>>>>>  static int serve_out_fd(int pid, int fd, struct file_desc *d)
>>>>>>  {
>>>>>> diff --git a/criu/include/files.h b/criu/include/files.h
>>>>>> index 5e3d6dc..06a1f98 100644
>>>>>> --- a/criu/include/files.h
>>>>>> +++ b/criu/include/files.h
>>>>>> @@ -62,6 +62,7 @@ extern int fill_fdlink(int lfd, const struct fd_parms *p, struct fd_link *link);
>>>>>>  
>>>>>>  struct file_desc;
>>>>>>  
>>>>>> +
>>>>>>  struct fdinfo_list_entry {
>>>>>>  	struct list_head	desc_list;	/* To chain on  @fd_info_head */
>>>>>>  	struct file_desc	*desc;		/* Associated file descriptor */
>>>>>> @@ -70,6 +71,8 @@ struct fdinfo_list_entry {
>>>>>>  	int			pid;
>>>>>>  	futex_t			real_pid;
>>>>>>  	FdinfoEntry		*fe;
>>>>>> +#define FD_LE_GHOST		0x1
>>>>>> +	unsigned		flags;
>>>>>>  };
>>>>>>  
>>>>>>  /* reports whether fd_a takes prio over fd_b */
>>>>>>
>>>>>> _______________________________________________
>>>>>> CRIU mailing list
>>>>>> CRIU at openvz.org
>>>>>> https://lists.openvz.org/mailman/listinfo/criu
>>>>>> .
>>>>>>
>>>>>
>>>> .
>>>>
>>>
> .
>