Re: [PATCH 6/6] tests/qtest: migration-test: Add tests for file-based migration

[Steven Sistare]

On 6/30/2023 11:05 AM, Fabiano Rosas wrote:
> Peter Xu <peterx@redhat.com> writes:
> 
>> On Wed, Jun 28, 2023 at 01:55:42PM -0300, Fabiano Rosas wrote:
>>> Add basic tests for file-based migration.
>>>
>>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>>> ---
>>>  tests/qtest/migration-test.c | 104 +++++++++++++++++++++++++++++++++++
>>>  1 file changed, 104 insertions(+)
>>>
>>> diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
>>> index acb778a8cd..b3019f54de 100644
>>> --- a/tests/qtest/migration-test.c
>>> +++ b/tests/qtest/migration-test.c
>>> @@ -52,6 +52,10 @@ static bool got_dst_resume;
>>>   */
>>>  #define DIRTYLIMIT_TOLERANCE_RANGE  25  /* MB/s */
>>>  
>>> +#define QEMU_VM_FILE_MAGIC 0x5145564d
>>> +#define FILE_TEST_FILENAME "migfile"
>>> +#define FILE_TEST_OFFSET 0x1000
>>> +
>>>  #if defined(__linux__)
>>>  #include <sys/syscall.h>
>>>  #include <sys/vfs.h>
>>> @@ -763,6 +767,7 @@ static void test_migrate_end(QTestState *from, 
>>> QTestState *to, bool test_dest)
>>>      cleanup("migsocket");
>>>      cleanup("src_serial");
>>>      cleanup("dest_serial");
>>> +    cleanup(FILE_TEST_FILENAME);
>>>  }
>>>  
>>>  #ifdef CONFIG_GNUTLS
>>> @@ -1460,11 +1465,28 @@ static void test_precopy_common(MigrateCommon *args)
>>>               */
>>>              wait_for_migration_complete(from);
>>>  
>>> +            /*
>>> +             * For file based migration the target must begin its
>>> +             * migration after the source has finished.
>>> +             */
>>> +            if (strstr(connect_uri, "file:")) {
>>> +                migrate_incoming_qmp(to, connect_uri, "{}");
>>> +            }
>>> +
>>>              if (!got_src_stop) {
>>>                  qtest_qmp_eventwait(from, "STOP");
>>>              }
>>>          } else {
>>>              wait_for_migration_complete(from);
>>> +
>>> +            /*
>>> +             * For file based migration the target must begin its
>>> +             * migration after the source has finished.
>>> +             */
>>> +            if (strstr(connect_uri, "file:")) {
>>> +                migrate_incoming_qmp(to, connect_uri, "{}");
>>> +            }
>>> +
>>>              /*
>>>               * Must wait for dst to finish reading all incoming
>>>               * data on the socket before issuing 'cont' otherwise
>>> @@ -1682,6 +1704,78 @@ static void test_precopy_unix_compress_nowait(void)
>>>      test_precopy_common(&args);
>>>  }
>>>  
>>> +static void test_precopy_file(void)
>>> +{
>>> +    g_autofree char *uri = g_strdup_printf("file:%s/%s", tmpfs,
>>> +                                           FILE_TEST_FILENAME);
>>> +    MigrateCommon args = {
>>> +        .connect_uri = uri,
>>> +        .listen_uri = "defer",
>>> +    };
>>> +
>>> +    test_precopy_common(&args);
>>> +}
>>> +
>>> +#if defined(__linux__)
>>> +static void file_offset_finish_hook(QTestState *from, QTestState *to, void 
>>> *opaque)
>>> +{
>>> +    g_autofree char *path = g_strdup_printf("%s/%s", tmpfs, 
>>> FILE_TEST_FILENAME);
>>> +    size_t size = FILE_TEST_OFFSET + sizeof(QEMU_VM_FILE_MAGIC);
>>> +    uintptr_t *addr, *p;
>>> +    int fd;
>>> +
>>> +    fd = open(path, O_RDONLY);
>>> +    g_assert(fd != -1);
>>> +    addr = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
>>
>> Not something that matters a lot, but RO mapping a file with private is a
>> bit weird.  Maybe just use MAP_SHARED?
>>
> 
> Yep
> 
>>> +    g_assert(addr != MAP_FAILED);
>>> +
>>> +    /*
>>> +     * Ensure the skipped offset contains zeros and the migration
>>> +     * stream starts at the right place.
>>> +     */
>>> +    p = addr;
>>> +    while (p < addr + FILE_TEST_OFFSET / sizeof(uintptr_t)) {
>>> +        g_assert(*p == 0);
>>> +        p++;
>>> +    }
>>> +    g_assert_cmpint(cpu_to_be32(*p), ==, QEMU_VM_FILE_MAGIC);
>>> +
>>> +    munmap(addr, size);
>>> +    close(fd);
>>> +}
>>> +
>>> +static void test_precopy_file_offset(void)
>>> +{
>>> +    g_autofree char *uri = g_strdup_printf("file:%s/%s,offset=%d", tmpfs,
>>> +                                           FILE_TEST_FILENAME,
>>> +                                           FILE_TEST_OFFSET);
>>
>> Is it intended to also only run this test with linux?  IIUC it should also
>> work for others. Maybe only file_offset_finish_hook() is optional?  Or am i
>> wrong?
>>
> 
> Yes, only the hook is linux-specific. I'll change it.
> 
>>> +    MigrateCommon args = {
>>> +        .connect_uri = uri,
>>> +        .listen_uri = "defer",
>>> +        .finish_hook = file_offset_finish_hook,
>>> +    };
>>> +
>>> +    test_precopy_common(&args);
>>> +}
>>> +#endif
>>> +
>>> +static void test_precopy_file_offset_bad(void)
>>> +{
>>> +    /* using a value not supported by qemu_strtosz() */
>>> +    g_autofree char *uri = g_strdup_printf("file:%s/migfile,offset=0x20M",
>>> +                                           tmpfs);
>>> +    MigrateCommon args = {
>>> +        .connect_uri = uri,
>>> +        .listen_uri = "defer",
>>> +        .error_str = g_strdup(
>>> +            "file URI has bad offset 0x20M: Unknown error -22"),
>>
>> "Unknown error" may imply that in Steve's patch the errno is inverted..
>>
>> Shall we not rely on the string in the test?  It might be too strict, I
>> worry, because error strings should be defined for human readers, and we
>> may not want some e.g. grammar / trivial change to break a test.
>>
> 
> Well, you just caught an issue with the errno by looking at the string,
> so maybe testing it is a good thing?
> 
> I'd expect anyone changing the string to run the test and catch the
> mismatch before sending a patch anyway.
> 
> I don't have a strong opinion about it, though. I can remove the
> error_str.

FWIW, I fixed the errno, so it should say
  file URI has bad offset 0x20M: EINVAL

- Steve