On Fri, Apr 26, 2024 at 11:20:42AM -0300, Fabiano Rosas wrote:
> Add a multifd test for mapped-ram with passing of fds into QEMU. This
> is how libvirt will consume the feature.
>
> There are a couple of details to the fdset mechanism:
>
> - multifd needs two distinct file descriptors (not duplicated with
> dup()) on the outgoing side so it can enable O_DIRECT only on the
> channels that write with alignment. The dup() system call creates
> file descriptors that share status flags, of which O_DIRECT is one.
>
> the incoming side doesn't set O_DIRECT, so it can dup() fds and
> therefore can receive only one in the fdset.
>
> - the open() access mode flags used for the fds passed into QEMU need
> to match the flags QEMU uses to open the file. Currently O_WRONLY
> for src and O_RDONLY for dst.
>
> O_DIRECT is not supported on all systems/filesystems, so run the fdset
> test without O_DIRECT if that's the case. The migration code should
> still work in that scenario.
If O_DIRECT is not supported, then we're not setting 'direct-io',
and thus isn't this test just duplicating coverage of existing
tests ?
If this test is specifically to cover O_DIRECT, then I'd just
#ifdef the entire thing with O_DIRECT.
>
> Signed-off-by: Fabiano Rosas <faro...@suse.de>
> ---
> tests/qtest/migration-test.c | 90 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 90 insertions(+)
>
> diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
> index 512b7ede8b..d83f1bdd4f 100644
> --- a/tests/qtest/migration-test.c
> +++ b/tests/qtest/migration-test.c
> @@ -2331,8 +2331,93 @@ static void test_multifd_file_mapped_ram_dio(void)
> test_file_common(&args, true);
> }
>
> +static void migrate_multifd_mapped_ram_fdset_dio_end(QTestState *from,
> + QTestState *to,
> + void *opaque)
> +{
> + QDict *resp;
> + QList *fdsets;
> +
> + file_offset_finish_hook(from, to, opaque);
> +
> + /*
> + * Check that we removed the fdsets after migration, otherwise a
> + * second migration would fail due to too many fdsets.
> + */
> +
> + resp = qtest_qmp(from, "{'execute': 'query-fdsets', "
> + "'arguments': {}}");
> + g_assert(qdict_haskey(resp, "return"));
> + fdsets = qdict_get_qlist(resp, "return");
> + g_assert(fdsets && qlist_empty(fdsets));
> +}
> #endif /* O_DIRECT */
>
> +#ifndef _WIN32
> +static void *migrate_multifd_mapped_ram_fdset(QTestState *from, QTestState
> *to)
> +{
> + g_autofree char *file = g_strdup_printf("%s/%s", tmpfs,
> FILE_TEST_FILENAME);
> + int fds[3];
> + int src_flags = O_WRONLY;
> +
> + file_dirty_offset_region();
> +
> + /* main outgoing channel: no O_DIRECT */
> + fds[0] = open(file, src_flags, 0660);
> + assert(fds[0] != -1);
> +
> + qtest_qmp_fds_assert_success(from, &fds[0], 1, "{'execute': 'add-fd', "
> + "'arguments': {'fdset-id': 1}}");
> +
> +#ifdef O_DIRECT
> + src_flags |= O_DIRECT;
> +
> + /* secondary outgoing channels */
> + fds[1] = open(file, src_flags, 0660);
> + assert(fds[1] != -1);
> +
> + qtest_qmp_fds_assert_success(from, &fds[1], 1, "{'execute': 'add-fd', "
> + "'arguments': {'fdset-id': 1}}");
> +
> + /* incoming channel */
> + fds[2] = open(file, O_CREAT | O_RDONLY, 0660);
> + assert(fds[2] != -1);
> +
> + qtest_qmp_fds_assert_success(to, &fds[2], 1, "{'execute': 'add-fd', "
> + "'arguments': {'fdset-id': 1}}");
> +
> + migrate_multifd_mapped_ram_dio_start(from, to);
> +#else
> + migrate_multifd_mapped_ram_start(from, to);
> +#endif
> +
> + return NULL;
> +}
> +
> +static void test_multifd_file_mapped_ram_fdset(void)
> +{
> + g_autofree char *uri = g_strdup_printf("file:/dev/fdset/1,offset=%d",
> + FILE_TEST_OFFSET);
> + MigrateCommon args = {
> + .connect_uri = uri,
> + .listen_uri = "defer",
> + .start_hook = migrate_multifd_mapped_ram_fdset,
> +#ifdef O_DIRECT
> + .finish_hook = migrate_multifd_mapped_ram_fdset_dio_end,
> +#endif
> + };
> +
> +#ifdef O_DIRECT
> + if (!probe_o_direct_support(tmpfs)) {
> + g_test_skip("Filesystem does not support O_DIRECT");
> + return;
> + }
> +#endif
> +
> + test_file_common(&args, true);
> +}
> +#endif /* _WIN32 */
> +
> static void test_precopy_tcp_plain(void)
> {
> MigrateCommon args = {
> @@ -3761,6 +3846,11 @@ int main(int argc, char **argv)
> test_multifd_file_mapped_ram_dio);
> #endif
>
> +#ifndef _WIN32
> + qtest_add_func("/migration/multifd/file/mapped-ram/fdset",
> + test_multifd_file_mapped_ram_fdset);
> +#endif
> +
> #ifdef CONFIG_GNUTLS
> migration_test_add("/migration/precopy/unix/tls/psk",
> test_precopy_unix_tls_psk);
> --
> 2.35.3
>
With regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
