1 files changed, 136 insertions, 0 deletions
diff --git a/src/blockdev-nbd.c b/src/blockdev-nbd.c
new file mode 100644
index 0000000..bcdd18b
--- /dev/null
+++ b/src/blockdev-nbd.c
@@ -0,0 +1,136 @@
+/*
+ * Serving QEMU block devices via NBD
+ *
+ * Copyright (c) 2012 Red Hat, Inc.
+ *
+ * Author: Paolo Bonzini <pbonzini@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#include "sysemu/blockdev.h"
+#include "sysemu/block-backend.h"
+#include "hw/block/block.h"
+#include "qapi/qmp/qerror.h"
+#include "sysemu/sysemu.h"
+#include "qmp-commands.h"
+#include "trace.h"
+#include "block/nbd.h"
+#include "qemu/sockets.h"
+
+static int server_fd = -1;
+
+static void nbd_accept(void *opaque)
+{
+    struct sockaddr_in addr;
+    socklen_t addr_len = sizeof(addr);
+
+    int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len);
+    if (fd >= 0 && !nbd_client_new(NULL, fd, nbd_client_put)) {
+        shutdown(fd, 2);
+        close(fd);
+    }
+}
+
+void qmp_nbd_server_start(SocketAddress *addr, Error **errp)
+{
+    if (server_fd != -1) {
+        error_setg(errp, "NBD server already running");
+        return;
+    }
+
+    server_fd = socket_listen(addr, errp);
+    if (server_fd != -1) {
+        qemu_set_fd_handler(server_fd, nbd_accept, NULL, NULL);
+    }
+}
+
+/*
+ * Hook into the BlockBackend notifiers to close the export when the
+ * backend is closed.
+ */
+typedef struct NBDCloseNotifier {
+    Notifier n;
+    NBDExport *exp;
+    QTAILQ_ENTRY(NBDCloseNotifier) next;
+} NBDCloseNotifier;
+
+static QTAILQ_HEAD(, NBDCloseNotifier) close_notifiers =
+    QTAILQ_HEAD_INITIALIZER(close_notifiers);
+
+static void nbd_close_notifier(Notifier *n, void *data)
+{
+    NBDCloseNotifier *cn = DO_UPCAST(NBDCloseNotifier, n, n);
+
+    notifier_remove(&cn->n);
+    QTAILQ_REMOVE(&close_notifiers, cn, next);
+
+    nbd_export_close(cn->exp);
+    nbd_export_put(cn->exp);
+    g_free(cn);
+}
+
+void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
+                        Error **errp)
+{
+    BlockBackend *blk;
+    NBDExport *exp;
+    NBDCloseNotifier *n;
+
+    if (server_fd == -1) {
+        error_setg(errp, "NBD server not running");
+        return;
+    }
+
+    if (nbd_export_find(device)) {
+        error_setg(errp, "NBD server already exporting device '%s'", device);
+        return;
+    }
+
+    blk = blk_by_name(device);
+    if (!blk) {
+        error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
+                  "Device '%s' not found", device);
+        return;
+    }
+    if (!blk_is_inserted(blk)) {
+        error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, device);
+        return;
+    }
+
+    if (!has_writable) {
+        writable = false;
+    }
+    if (blk_is_read_only(blk)) {
+        writable = false;
+    }
+
+    exp = nbd_export_new(blk, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY, NULL,
+                         errp);
+    if (!exp) {
+        return;
+    }
+
+    nbd_export_set_name(exp, device);
+
+    n = g_new0(NBDCloseNotifier, 1);
+    n->n.notify = nbd_close_notifier;
+    n->exp = exp;
+    blk_add_close_notifier(blk, &n->n);
+    QTAILQ_INSERT_TAIL(&close_notifiers, n, next);
+}
+
+void qmp_nbd_server_stop(Error **errp)
+{
+    while (!QTAILQ_EMPTY(&close_notifiers)) {
+        NBDCloseNotifier *cn = QTAILQ_FIRST(&close_notifiers);
+        nbd_close_notifier(&cn->n, nbd_export_get_blockdev(cn->exp));
+    }
+
+    if (server_fd != -1) {
+        qemu_set_fd_handler(server_fd, NULL, NULL, NULL);
+        close(server_fd);
+        server_fd = -1;
+    }
+}