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Re: [Xen-devel] [PATCH 20/27] tools/libxl: Infrastructure for writing a v2 stream





On 06/15/2015 09:44 PM, Andrew Cooper wrote:
[...]
+
+static void stream_success(libxl__egc *egc,
+                           libxl__stream_write_state *stream);
+static void stream_failed(libxl__egc *egc,
+                          libxl__stream_write_state *stream, int ret);
+static void stream_done(libxl__egc *egc,
+                        libxl__stream_write_state *stream);
+
+static void check_stream_finished(libxl__egc *egc,
+                                  libxl__domain_suspend_state *dcs,

s/dcs/dss/

+                                  int rc, const char *what);
+
+/* Event callbacks for plain VM. */
+static void stream_header_done(libxl__egc *egc,
+                               libxl__datacopier_state *dc,
+                               int onwrite, int errnoval);
+static void libxc_header_done(libxl__egc *egc,
+                              libxl__datacopier_state *dc,
+                              int onwrite, int errnoval);
+/* libxl__xc_domain_save_done() lives here, event-order wise. */
+static void write_toolstack_record(libxl__egc *egc,
+                                   libxl__stream_write_state *stream);
+static void toolstack_record_done(libxl__egc *egc,
+                                  libxl__datacopier_state *dc,
+                                  int onwrite, int errnoval);
+static void write_emulator_record(libxl__egc *egc,
+                                  libxl__stream_write_state *stream);
+static void emulator_body_done(libxl__egc *egc,
+                               libxl__datacopier_state *dc,
+                               int onwrite, int errnoval);
+static void emulator_padding_done(libxl__egc *egc,
+                                  libxl__datacopier_state *dc,
+                                  int onwrite, int errnoval);
+static void write_end_record(libxl__egc *egc,
+                             libxl__stream_write_state *stream);
+static void end_record_done(libxl__egc *egc,
+                            libxl__datacopier_state *dc,
+                            int onwrite, int errnoval);
+
+void libxl__stream_write_start(libxl__egc *egc,
+                               libxl__stream_write_state *stream)
+{
+    libxl__datacopier_state *dc = &stream->dc;
+    STATE_AO_GC(stream->ao);
+    struct libxl_sr_hdr hdr = { 0 };
+    int ret = 0;
+
+    assert(!stream->running);
+    stream->running = true;
+
+    memset(dc, 0, sizeof(*dc));
+    dc->readwhat = "";
+    dc->copywhat = "suspend header";
+    dc->writewhat = "save/migration stream";
+    dc->ao = ao;
+    dc->readfd = -1;
+    dc->writefd = stream->fd;
+    dc->maxsz = INT_MAX;
+    dc->bytes_to_read = INT_MAX;
+    dc->callback = stream_header_done;
+
+    ret = libxl__datacopier_start(dc);
+    if (ret)
+        goto err;
+
+    hdr.ident   = htobe64(RESTORE_STREAM_IDENT);
+    hdr.version = htobe32(RESTORE_STREAM_VERSION);
+    hdr.options = htobe32(0);
+
+    libxl__datacopier_prefixdata(egc, dc, &hdr, sizeof(hdr));
+    return;
+
+ err:
+    assert(ret);
+    stream_failed(egc, stream, ret);
+}
+
+void libxl__stream_write_abort(libxl__egc *egc,
+                               libxl__stream_write_state *stream, int rc)
+{
+    stream_failed(egc, stream, rc);
+}
+
+static void stream_success(libxl__egc *egc, libxl__stream_write_state *stream)
+{
+    stream->rc = 0;
+    stream->running = false;
+
+    stream_done(egc, stream);
+}
+
+static void stream_failed(libxl__egc *egc,
+                          libxl__stream_write_state *stream, int rc)
+{
+    assert(rc);
+    stream->rc = rc;
+
+    if (stream->running) {
+        stream->running = false;
+        stream_done(egc, stream);
+    }
+}
+
+static void stream_done(libxl__egc *egc,
+                        libxl__stream_write_state *stream)
+{
+    libxl__domain_suspend_state *dss = CONTAINER_OF(stream, *dss, sws);
+
+    assert(!stream->running);
+
+    check_stream_finished(egc, dss, stream->rc, "stream");
+}
+
+static void check_stream_finished(libxl__egc *egc,
+                                  libxl__domain_suspend_state *dss,
+                                  int rc, const char *what)
+{
+    libxl__stream_write_state *stream = &dss->sws;
+    STATE_AO_GC(dss->ao);
+
+    LOG(INFO, "Task '%s' joining (rc %d)", what, rc);
+
+    if (rc && !stream->joined_rc) {
+        bool skip = false;
+        /* First reported failure from joining tasks.  Tear everything down */
+        stream->joined_rc = rc;
+
+        if (libxl__stream_write_inuse(&dss->sws)) {
+            skip = true;
+            libxl__stream_write_abort(egc, &dss->sws, rc);
+        }
+
+        if (libxl__save_helper_inuse(&dss->shs)) {
+            skip = true;
+            libxl__save_helper_abort(egc, &dss->shs);
+        }
+
+        /* There is at least one more active task to join - wait for its
+           callback */
+        if ( skip )
+            return;
+    }
+
+    if (libxl__stream_write_inuse(&dss->sws))
+        LOG(DEBUG, "stream still in use");
+    else if (libxl__save_helper_inuse(&dss->shs))
+        LOG(DEBUG, "save/restore still in use");
+    else {
+        LOG(INFO, "Join complete: result %d", stream->joined_rc);
+        stream->completion_callback(egc, dss, stream->joined_rc);
+    }
+}
+
+static void stream_header_done(libxl__egc *egc,
+                               libxl__datacopier_state *dc,
+                               int onwrite, int errnoval)
+{
+    libxl__stream_write_state *stream = CONTAINER_OF(dc, *stream, dc);
+    STATE_AO_GC(stream->ao);
+    struct libxl_sr_rec_hdr rec = { REC_TYPE_LIBXC_CONTEXT, 0 };
+    int ret = 0;
+
+    if (onwrite || errnoval) {
+        ret = ERROR_FAIL;
+        goto err;
+    }
+
+    dc->copywhat = "suspend footer";
+    dc->writewhat = "save/migration stream";
+    dc->callback = libxc_header_done;
+
+    ret = libxl__datacopier_start(dc);
+    if (ret)
+        goto err;
+
+    libxl__datacopier_prefixdata(egc, dc, &rec, sizeof(rec));
+    return;
+
+ err:
+    assert(ret);
+    stream_failed(egc, stream, ret);
+}
+
+static void libxc_header_done(libxl__egc *egc,
+                              libxl__datacopier_state *dc,
+                              int onwrite, int errnoval)
+{
+    libxl__stream_write_state *stream = CONTAINER_OF(dc, *stream, dc);
+    libxl__domain_suspend_state *dss = CONTAINER_OF(stream, *dss, sws);
+    STATE_AO_GC(stream->ao);
+    int ret = 0;
+
+    if (onwrite || errnoval) {
+        ret = ERROR_FAIL;
+        goto err;
+    }
+
+    libxl__xc_domain_save(egc, dss);
+    return;
+
+ err:
+    assert(ret);
+    stream_failed(egc, stream, ret);
+}
+
+static void __attribute__((used))
+will_be_libxl__xc_domain_save_done(libxl__egc *egc, void *dss_void,
+                                int rc, int retval, int errnoval)
+{
+    libxl__domain_suspend_state *dss = dss_void;
+    libxl__stream_write_state *stream = &dss->sws;
+    STATE_AO_GC(dss->ao);
+
+    if (rc)
+        goto err;
+
+    if (retval) {
+        LOGEV(ERROR, errnoval, "saving domain: %s",
+                         dss->guest_responded ?
+                         "domain responded to suspend request" :
+                         "domain did not respond to suspend request");
+        if ( !dss->guest_responded )
+            rc = ERROR_GUEST_TIMEDOUT;
+        else
+            rc = ERROR_FAIL;
+        goto err;
+    }
+
+    write_toolstack_record(egc, stream);
+    return;
+
+ err:
+    assert(rc);
+    check_stream_finished(egc, dss, rc, "save/restore helper");
+}
+
+static void write_toolstack_record(libxl__egc *egc,
+                                   libxl__stream_write_state *stream)
+{
+    libxl__domain_suspend_state *dss = CONTAINER_OF(stream, *dss, sws);
+    libxl__datacopier_state *dc = &stream->dc;
+    STATE_AO_GC(stream->ao);
+    struct libxl_sr_rec_hdr rec = { REC_TYPE_XENSTORE_DATA, 0 };
+    int ret = 0;
+    uint8_t *toolstack_buf = NULL; /* We must free this. */
+    uint32_t toolstack_len, padding_len;
+
+    ret = libxl__toolstack_save(dss->domid, &toolstack_buf,
+                                &toolstack_len, dss);
+    if (ret)
+        goto err;
+
+    dc->copywhat = "toolstack record";
+    dc->writewhat = "save/migration stream";
+    dc->callback = toolstack_record_done;
+
+    ret = libxl__datacopier_start(dc);
+    if (ret)
+        goto err;
+
+    rec.length = toolstack_len;
+
+    libxl__datacopier_prefixdata(egc, dc, &rec, sizeof(rec));
+    libxl__datacopier_prefixdata(egc, dc, toolstack_buf, toolstack_len);
+
+    padding_len = ROUNDUP(rec.length, REC_ALIGN_ORDER) - rec.length;
+    if (padding_len)
+        libxl__datacopier_prefixdata(egc, dc, zero_padding, padding_len);
+
+    free(toolstack_buf);
+    return;
+
+ err:
+    assert(ret);
+    free(toolstack_buf);
+    stream_failed(egc, stream, ret);
+}
+
+static void toolstack_record_done(libxl__egc *egc,
+                                  libxl__datacopier_state *dc,
+                                  int onwrite, int errnoval)
+{
+    libxl__stream_write_state *stream = CONTAINER_OF(dc, *stream, dc);
+    libxl__domain_suspend_state *dss = CONTAINER_OF(stream, *dss, sws);
+    STATE_AO_GC(stream->ao);
+    int ret = 0;
+
+    if (onwrite || errnoval) {
+        ret = ERROR_FAIL;
+        goto err;
+    }
+
+    if (dss->type == LIBXL_DOMAIN_TYPE_HVM)
+        write_emulator_record(egc, stream);
+    else
+        write_end_record(egc, stream);
+
+    return;
+
+ err:
+    assert(ret);
+    stream_failed(egc, stream, ret);
+}
+
+static void write_emulator_record(libxl__egc *egc,
+                                  libxl__stream_write_state *stream)
+{
+    libxl__domain_suspend_state *dss = CONTAINER_OF(stream, *dss, sws);
+    libxl__datacopier_state *dc = &stream->dc;
+    STATE_AO_GC(stream->ao);
+    struct libxl_sr_rec_hdr rec = { REC_TYPE_EMULATOR_CONTEXT, 0 };
+    struct libxl_sr_emulator_hdr ehdr = { 0 };
+    struct stat st;
+    int ret = 0;
+    uint32_t qemu_state_len;
+
+    assert(dss->type == LIBXL_DOMAIN_TYPE_HVM);
+
+    /* Convenience aliases */
+    const char *const filename = dss->dm_savefile;
+    const uint32_t domid = dss->domid;
+
+    switch(libxl__device_model_version_running(gc, domid)) {
+    case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL:
+        ehdr.id = EMULATOR_QEMU_TRADITIONAL;
+        break;
+
+    case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN:
+        ehdr.id = EMULATOR_QEMU_UPSTREAM;
+        break;
+
+    default:
+        ret = ERROR_FAIL;
+        goto err;
+    }
+
+    ret = libxl__domain_suspend_device_model(gc, dss);
+    if (ret)
+        goto err;
+
+    dc->readwhat = GCSPRINTF("qemu save file %s", filename);
+    dc->copywhat = "emulator record";
+    dc->writewhat = "save/migration stream";
+    dc->callback = emulator_body_done;
+
+    dc->readfd = open(filename, O_RDONLY);
+    if (dc->readfd < 0) {
+        LOGE(ERROR, "unable to open %s", dc->readwhat);
+        goto err;
+    }
+
+    if (fstat(dc->readfd, &st))
+    {
+        LOGE(ERROR, "unable to fstat %s", dc->readwhat);
+        goto err;
+    }
+
+    if (!S_ISREG(st.st_mode)) {
+        LOG(ERROR, "%s is not a plain file!", dc->readwhat);
+        goto err;
+    }
+
+    qemu_state_len = st.st_size;
+    rec.length = qemu_state_len + sizeof(ehdr);
+
+    ret = libxl__datacopier_start(dc);
+    if (ret)
+        goto err;
+
+    libxl__datacopier_prefixdata(egc, dc, &rec, sizeof(rec));
+    libxl__datacopier_prefixdata(egc, dc, &ehdr, sizeof(ehdr));
+
+    stream->padding = ROUNDUP(qemu_state_len, REC_ALIGN_ORDER) - 
qemu_state_len;
+    return;
+
+ err:
+    assert(ret);
+    stream_failed(egc, stream, ret);
+}
+
+static void emulator_body_done(libxl__egc *egc,
+                               libxl__datacopier_state *dc,
+                               int onwrite, int errnoval)
+{
+    libxl__stream_write_state *stream = CONTAINER_OF(dc, *stream, dc);
+    STATE_AO_GC(stream->ao);
+    int ret = 0;
+
+    if (onwrite || errnoval) {
+        ret = ERROR_FAIL;
+        goto err;
+    }
+
+    dc->readwhat = "";
+    dc->readfd = -1;
+
+    if (stream->padding) {
+        assert(stream->padding < (1U << REC_ALIGN_ORDER));
+
+        dc->copywhat = "emulator padding";
+        dc->writewhat = "save/migration stream";
+        dc->callback = emulator_padding_done;
+
+        ret = libxl__datacopier_start(dc);
+        if (ret)
+            goto err;
+
+        libxl__datacopier_prefixdata(egc, dc, zero_padding, stream->padding);
+        return;
+    }
+
+    emulator_padding_done(egc, dc, 0, 0);
+    return;
+
+ err:
+    assert(ret);
+    stream_failed(egc, stream, ret);
+}
+
+static void emulator_padding_done(libxl__egc *egc,
+                                  libxl__datacopier_state *dc,
+                                  int onwrite, int errnoval)
+{
+    libxl__stream_write_state *stream = CONTAINER_OF(dc, *stream, dc);
+    STATE_AO_GC(stream->ao);
+    int ret = 0;
+
+    if (onwrite || errnoval) {
+        ret = ERROR_FAIL;
+        goto err;
+    }
+
+    write_end_record(egc, stream);
+    return;
+
+ err:
+    assert(ret);
+    stream_failed(egc, stream, ret);
+}
+
+static void write_end_record(libxl__egc *egc,
+                             libxl__stream_write_state *stream)
+{
+    libxl__datacopier_state *dc = &stream->dc;
+    STATE_AO_GC(stream->ao);
+    struct libxl_sr_rec_hdr rec = { REC_TYPE_END, 0 };
+    int ret = 0;
+
+    dc->copywhat = "suspend footer";
+    dc->writewhat = "save/migration stream";
+    dc->callback = end_record_done;
+
+    ret = libxl__datacopier_start(dc);
+    if (ret)
+        goto err;
+
+    libxl__datacopier_prefixdata(egc, dc, &rec, sizeof(rec));
+    return;
+
+ err:
+    assert(ret);
+    stream_failed(egc, stream, ret);
+}
+
+static void end_record_done(libxl__egc *egc,
+                            libxl__datacopier_state *dc,
+                            int onwrite, int errnoval)
+{
+    libxl__stream_write_state *stream = CONTAINER_OF(dc, *stream, dc);
+    STATE_AO_GC(stream->ao);
+    int ret = 0;
+
+    if (onwrite || errnoval) {
+        ret = ERROR_FAIL;
+        goto err;
+    }
+
+    stream_success(egc, stream);
+    return;
+
+ err:
+    assert(ret);
+    stream_failed(egc, stream, ret);
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */


--
Thanks,
Yang.

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