tests/qtest/migration: Add tests for file migration with direct-io

The tests are only allowed to run in systems that know about the
O_DIRECT flag and in filesystems which support it.

Note: this also brings back migrate_set_parameter_bool() which went
away when we removed the compression tests. I copied it verbatim.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>

tests/qtest/migration-helpers.c

@@ -18,6 +18,7 @@
 #include "qapi/error.h"
 #include "qapi/qmp/qlist.h"
 #include "qemu/cutils.h"
+#include "qemu/memalign.h"
 
 #include "migration-helpers.h"
 
@@ -473,3 +474,46 @@ void migration_test_add(const char *path, void (*fn)(void))
     qtest_add_data_func_full(path, test, migration_test_wrapper,
                              migration_test_destroy);
 }
+
+#ifdef O_DIRECT
+/*
+ * Probe for O_DIRECT support on the filesystem. Since this is used
+ * for tests, be conservative, if anything fails, assume it's
+ * unsupported.
+ */
+bool probe_o_direct_support(const char *tmpfs)
+{
+    g_autofree char *filename = g_strdup_printf("%s/probe-o-direct", tmpfs);
+    int fd, flags = O_CREAT | O_RDWR | O_TRUNC | O_DIRECT;
+    void *buf;
+    ssize_t ret, len;
+    uint64_t offset;
+
+    fd = open(filename, flags, 0660);
+    if (fd < 0) {
+        unlink(filename);
+        return false;
+    }
+
+    /*
+     * Using 1MB alignment as conservative choice to satisfy any
+     * plausible architecture default page size, and/or filesystem
+     * alignment restrictions.
+     */
+    len = 0x100000;
+    offset = 0x100000;
+
+    buf = qemu_try_memalign(len, len);
+    g_assert(buf);
+
+    ret = pwrite(fd, buf, len, offset);
+    unlink(filename);
+    g_free(buf);
+
+    if (ret < 0) {
+        return false;
+    }
+
+    return true;
+}
+#endif

tests/qtest/migration-helpers.h

@@ -54,5 +54,13 @@ char *find_common_machine_version(const char *mtype, const char *var1,
                                   const char *var2);
 char *resolve_machine_version(const char *alias, const char *var1,
                               const char *var2);
+#ifdef O_DIRECT
+bool probe_o_direct_support(const char *tmpfs);
+#else
+static inline bool probe_o_direct_support(const char *tmpfs)
+{
+    return false;
+}
+#endif
 void migration_test_add(const char *path, void (*fn)(void));
 #endif /* MIGRATION_HELPERS_H */

tests/qtest/migration-test.c

@@ -408,6 +408,38 @@ static void migrate_set_parameter_str(QTestState *who, const char *parameter,
     migrate_check_parameter_str(who, parameter, value);
 }
 
+static long long migrate_get_parameter_bool(QTestState *who,
+                                           const char *parameter)
+{
+    QDict *rsp;
+    int result;
+
+    rsp = qtest_qmp_assert_success_ref(
+        who, "{ 'execute': 'query-migrate-parameters' }");
+    result = qdict_get_bool(rsp, parameter);
+    qobject_unref(rsp);
+    return !!result;
+}
+
+static void migrate_check_parameter_bool(QTestState *who, const char *parameter,
+                                        int value)
+{
+    int result;
+
+    result = migrate_get_parameter_bool(who, parameter);
+    g_assert_cmpint(result, ==, value);
+}
+
+static void migrate_set_parameter_bool(QTestState *who, const char *parameter,
+                                      int value)
+{
+    qtest_qmp_assert_success(who,
+                             "{ 'execute': 'migrate-set-parameters',"
+                             "'arguments': { %s: %i } }",
+                             parameter, value);
+    migrate_check_parameter_bool(who, parameter, value);
+}
+
 static void migrate_ensure_non_converge(QTestState *who)
 {
     /* Can't converge with 1ms downtime + 3 mbs bandwidth limit */
@@ -2235,6 +2267,33 @@ static void test_multifd_file_mapped_ram(void)
     test_file_common(&args, true);
 }
 
+static void *multifd_mapped_ram_dio_start(QTestState *from, QTestState *to)
+{
+    migrate_multifd_mapped_ram_start(from, to);
+
+    migrate_set_parameter_bool(from, "direct-io", true);
+    migrate_set_parameter_bool(to, "direct-io", true);
+
+    return NULL;
+}
+
+static void test_multifd_file_mapped_ram_dio(void)
+{
+    g_autofree char *uri = g_strdup_printf("file:%s/%s", tmpfs,
+                                           FILE_TEST_FILENAME);
+    MigrateCommon args = {
+        .connect_uri = uri,
+        .listen_uri = "defer",
+        .start_hook = multifd_mapped_ram_dio_start,
+    };
+
+    if (!probe_o_direct_support(tmpfs)) {
+        g_test_skip("Filesystem does not support O_DIRECT");
+        return;
+    }
+
+    test_file_common(&args, true);
+}
 
 static void test_precopy_tcp_plain(void)
 {
@@ -3674,6 +3733,9 @@ int main(int argc, char **argv)
     migration_test_add("/migration/multifd/file/mapped-ram/live",
                        test_multifd_file_mapped_ram_live);
 
+    migration_test_add("/migration/multifd/file/mapped-ram/dio",
+                       test_multifd_file_mapped_ram_dio);
+
 #ifdef CONFIG_GNUTLS
     migration_test_add("/migration/precopy/unix/tls/psk",
                        test_precopy_unix_tls_psk);