[CRIU] [PATCH RFC 7/8] criu: uffd: add --lazy-addr option

[Mike Rapoport]

On Fri, May 27, 2016 at 10:33 PM, Pavel Emelyanov <xemul at virtuozzo.com> wrote:
> On 05/21/2016 01:49 PM, Mike Rapoport wrote:
>> to distinguish between UNIX socket address for passing uffd and the address
>> of the remote dump
>
> Would you show when the --addredd and --lazy-addr confusion may occur?

Well, we can skip --lazy-addr if we will fork() lazy-pages from
cr-restore. Then the unix socket will be created in cr-restore and
inherited by lazy-pages daemon.

Another possibility is to make lazy-pages daemon a variation of the
page-server that does not depend on existing checkpoint directory,
like Adrian suggested a while ago.
Then it will get the required information via the unix socket. For
instance, in addition to pid and uffd, lazy-pages daemon will receive
the path to relevant checkpoint directory.

>> Signed-off-by: Mike Rapoport <rppt at linux.vnet.ibm.com>
>> ---
>>  criu/crtools.c            |  4 ++++
>>  criu/include/cr_options.h |  1 +
>>  criu/uffd.c               | 26 +++++++++++++-------------
>>  3 files changed, 18 insertions(+), 13 deletions(-)
>>
>> diff --git a/criu/crtools.c b/criu/crtools.c
>> index b35a4b0..b3962e5 100644
>> --- a/criu/crtools.c
>> +++ b/criu/crtools.c
>> @@ -322,6 +322,7 @@ int main(int argc, char *argv[], char *envp[])
>>               { "all",                        no_argument,            0, 1079 },
>>               { "cgroup-props",               required_argument,      0, 1080 },
>>               { "cgroup-props-file",          required_argument,      0, 1081 },
>> +             { "lazy-addr",                  required_argument,      0, 1082 },
>>               { },
>>       };
>>
>> @@ -627,6 +628,9 @@ int main(int argc, char *argv[], char *envp[])
>>               case 1081:
>>                       opts.cgroup_props_file = optarg;
>>                       break;
>> +             case 1082:
>> +                     opts.lazy_addr = optarg;
>> +                     break;
>>               case 'V':
>>                       pr_msg("Version: %s\n", CRIU_VERSION);
>>                       if (strcmp(CRIU_GITID, "0"))
>> diff --git a/criu/include/cr_options.h b/criu/include/cr_options.h
>> index e36c362..641f0e5 100644
>> --- a/criu/include/cr_options.h
>> +++ b/criu/include/cr_options.h
>> @@ -111,6 +111,7 @@ struct cr_options {
>>       unsigned int            timeout;
>>       unsigned int            empty_ns;
>>       bool                    lazy_pages;
>> +     char                    *lazy_addr;
>>  };
>>
>>  extern struct cr_options opts;
>> diff --git a/criu/uffd.c b/criu/uffd.c
>> index 1dadc23..ef1ff89 100644
>> --- a/criu/uffd.c
>> +++ b/criu/uffd.c
>> @@ -115,18 +115,18 @@ static int send_uffd(int sendfd, int pid)
>>       int ret = -1;
>>       struct sockaddr_un sun;
>>
>> -     if (!opts.addr) {
>> +     if (!opts.lazy_addr) {
>>               pr_info("Please specify a file name for the unix domain socket\n");
>>               pr_info("used to communicate between the lazy-pages server\n");
>> -             pr_info("and the restore process. Use the --address option like\n");
>> -             pr_info("criu restore --lazy-pages --address /tmp/userfault.socket\n");
>> +             pr_info("and the restore process. Use the --lazy-addr option like\n");
>> +             pr_info("criu restore --lazy-pages --lazy-addr /tmp/uffd.sock\n");
>>               return -1;
>>       }
>>
>>       if (sendfd < 0)
>>               return -1;
>>
>> -     if (strlen(opts.addr) >= sizeof(sun.sun_path)) {
>> +     if (strlen(opts.lazy_addr) >= sizeof(sun.sun_path)) {
>>               return -1;
>>       }
>>
>> @@ -135,10 +135,10 @@ static int send_uffd(int sendfd, int pid)
>>
>>       memset(&sun, 0, sizeof(sun));
>>       sun.sun_family = AF_UNIX;
>> -     strcpy(sun.sun_path, opts.addr);
>> -     len = offsetof(struct sockaddr_un, sun_path) + strlen(opts.addr);
>> +     strcpy(sun.sun_path, opts.lazy_addr);
>> +     len = offsetof(struct sockaddr_un, sun_path) + strlen(opts.lazy_addr);
>>       if (connect(fd, (struct sockaddr *) &sun, len) < 0) {
>> -             pr_perror("connect to %s failed", opts.addr);
>> +             pr_perror("connect to %s failed", opts.lazy_addr);
>>               goto out;
>>       }
>>
>> @@ -225,19 +225,19 @@ static int server_listen(struct sockaddr_un *saddr)
>>       int fd;
>>       int len;
>>
>> -     if (strlen(opts.addr) >= sizeof(saddr->sun_path)) {
>> +     if (strlen(opts.lazy_addr) >= sizeof(saddr->sun_path)) {
>>               return -1;
>>       }
>>
>>       if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
>>               return -1;
>>
>> -     unlink(opts.addr);
>> +     unlink(opts.lazy_addr);
>>
>>       memset(saddr, 0, sizeof(struct sockaddr_un));
>>       saddr->sun_family = AF_UNIX;
>> -     strcpy(saddr->sun_path, opts.addr);
>> -     len = offsetof(struct sockaddr_un, sun_path) + strlen(opts.addr);
>> +     strcpy(saddr->sun_path, opts.lazy_addr);
>> +     len = offsetof(struct sockaddr_un, sun_path) + strlen(opts.lazy_addr);
>>
>>       if (bind(fd, (struct sockaddr *) saddr, len) < 0) {
>>               goto out;
>> @@ -808,7 +808,7 @@ static int prepare_uffds(int epollfd)
>>       int listen;
>>       struct sockaddr_un saddr;
>>
>> -     pr_debug("Waiting for incoming connections on %s\n", opts.addr);
>> +     pr_debug("Waiting for incoming connections on %s\n", opts.lazy_addr);
>>       if ((listen = server_listen(&saddr)) < 0) {
>>               pr_perror("server_listen error");
>>               return -1;
>> @@ -841,7 +841,7 @@ int cr_lazy_pages()
>>       if (check_for_uffd())
>>               return -1;
>>
>> -     if (!opts.addr) {
>> +     if (!opts.lazy_addr) {
>>               pr_info("Please specify a file name for the unix domain socket\n");
>>               pr_info("used to communicate between the lazy-pages server\n");
>>               pr_info("and the restore process. Use the --address option like\n");
>>
>



-- 
Sincerely yours,
Mike.