[CRIU] [PATCH v4 07/17] autofs: dump stage introduced

[Stanislav Kinsburskiy]

19.01.2016 14:58, Pavel Emelyanov пишет:
> On 01/07/2016 07:09 PM, Stanislav Kinsburskiy wrote:
>> AutoFS mount point is managed by user space daemon, which receives requests
>> from kernel via pipe, passed on mount operation.
>> Kernel hold write end, while user space process - read end.
>> Thus, for successfull AutoFS migration, this connection has to be restored.
>>
>> The major trick for dump stage is that mount points are collected (parsed)
>> from initial pid namespace, which leads to real pgrp value in AutoFS options
>> instead of virtual one. This have to be fixed.
>>
>> Note: we don't care about virtual pgrp in case of catatonic mounts
>>
>> Signed-off-by: Stanislav Kinsburskiy <skinsbursky at virtuozzo.com>
>> ---
>>   autofs.c         |   24 ++++++++++++++++++++++++
>>   include/autofs.h |    1 +
>>   mount.c          |    1 +
>>   3 files changed, 26 insertions(+)
>>
>> diff --git a/autofs.c b/autofs.c
>> index c2aafa6..1f7509f 100644
>> --- a/autofs.c
>> +++ b/autofs.c
>> @@ -300,3 +300,27 @@ int autofs_parse(struct mount_info *pm, bool for_dump)
>>   
>>   	return 0;
>>   }
>> +
>> +int autofs_dump(struct mount_info *pm)
>> +{
>> +	AutofsEntry *entry = pm->autofs;
>> +	struct mount_info *mi;
>> +
>> +	if (entry->fd == AUTOFS_CATATONIC_FD)
>> +		return 0;
>> +
>> +	/* We need to get virtual pgrp to restore mount */
>> +	entry->pgrp = pid_to_virt(entry->pgrp);
>> +	if (!entry->pgrp) {
>> +		pr_err("failed to find pstree item with pid %d\n",
>> +				entry->pgrp);
>> +		pr_err("Non-catatonic mount without master?\n");
>> +		return -1;
>> +	}
>> +
>> +	/* Fix pgrp for all bind-mounts */
>> +	list_for_each_entry(mi, &pm->mnt_bind, mnt_bind)
>> +		mi->autofs->pgrp = entry->pgrp;
> Do they all have mi->autofs? This pointer is set in dump_one_mountpoint()
> and by the time you get here for the first pm, all the others still
> have NULL there.
>

Yes, all of them has it, because it's allocated on "parse stage" for all 
the mounts, which is called before.