[Qemu-devel] [PULL 4/4] qmp: add nbd-server-remove

[Eric Blake <eblake@redhat.com>]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Add command for export removing. It is needed for cases when we
don't want to keep export after the operation on it was completed.
The other example is temporary node, created with blockdev-add.
If we want to delete it we should firstly remove corresponding
NBD export.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20171109154049.42386-3-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 qapi/block.json | 20 ++++++++++++++++++++
 blockdev-nbd.c  | 27 +++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/qapi/block.json b/qapi/block.json
index f093fa3f27..1827940717 100644
--- a/qapi/block.json
+++ b/qapi/block.json
@@ -222,6 +222,26 @@
 ##
 { 'command': 'nbd-server-add', 'data': {'device': 'str', '*writable': 'bool'} }

+##
+# @nbd-server-remove:
+#
+# Stop exporting block node through QEMU's embedded NBD server.
+#
+# @device: The device name or node name of the exported node. Should be equal
+#          to @device parameter for corresponding nbd-server-add command call.
+#
+# @force: Whether active connections to the export should be closed. If this
+#         parameter is false the export is only removed from named exports list,
+#         so new connetions are impossible and it would be freed after all
+#         clients are disconnected (default false).
+#
+# Returns: error if the server is not running or the device is not marked for
+#          export.
+#
+# Since: 2.12
+##
+{ 'command': 'nbd-server-remove', 'data': {'device': 'str', '*force': 'bool'} }
+
 ##
 # @nbd-server-stop:
 #
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 28f551a7b0..5f66951c33 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -203,6 +203,33 @@ void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
     nbd_export_put(exp);
 }

+void qmp_nbd_server_remove(const char *device, bool has_force, bool force,
+                           Error **errp)
+{
+    NBDExport *exp;
+
+    if (!nbd_server) {
+        error_setg(errp, "NBD server not running");
+        return;
+    }
+
+    exp = nbd_export_find(device);
+    if (exp == NULL) {
+        error_setg(errp, "'%s' is not exported", device);
+        return;
+    }
+
+    if (!has_force) {
+        force = false;
+    }
+
+    if (force) {
+        nbd_export_close(exp);
+    } else {
+        nbd_export_set_name(exp, NULL);
+    }
+}
+
 void qmp_nbd_server_stop(Error **errp)
 {
     nbd_export_close_all();
-- 
2.14.3