monitor usb: Inline monitor_read_bdrv_key_start()'s first part

monitor_read_bdrv_key_start() does several things:

1. If no key is needed, call completion_cb() and succeed

2. If we're in QMP context, call qerror_report_err() and fail

3. Start reading the key in the monitor.

This is two things too many.  Inline 1. and 2. into its callers
monitor_read_block_device_key() and usb_msd_realize_storage().

Since monitor_read_block_device_key() only ever runs in HMP context,
drop 2. there.

The next commit will clean up the result in usb_msd_realize_storage().

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

hw/usb/dev-storage.c

@@ -641,8 +641,17 @@ static void usb_msd_realize_storage(USBDevice *dev, Error **errp)
 
     if (bdrv_key_required(blk_bs(blk))) {
         if (cur_mon) {
-            monitor_read_bdrv_key_start(cur_mon, blk_bs(blk),
-                                        usb_msd_password_cb, s);
+            bdrv_add_key(blk_bs(blk), NULL, &err);
+            if (!err) {
+                usb_msd_password_cb(s, 0);
+            } else if (monitor_cur_is_qmp()) {
+                qerror_report_err(err);
+                error_free(err);
+            } else {
+                error_free(err);
+                monitor_read_bdrv_key_start(cur_mon, blk_bs(blk),
+                                            usb_msd_password_cb, s);
+            }
             s->dev.auto_attach = 0;
         } else {
             autostart = 0;

monitor.c

@@ -5377,25 +5377,8 @@ int monitor_read_bdrv_key_start(Monitor *mon, BlockDriverState *bs,
                                 BlockCompletionFunc *completion_cb,
                                 void *opaque)
 {
-    Error *local_err = NULL;
     int err;
 
-    bdrv_add_key(bs, NULL, &local_err);
-    if (!local_err) {
-        if (completion_cb)
-            completion_cb(opaque, 0);
-        return 0;
-    }
-
-    /* Need a key for @bs */
-
-    if (monitor_ctrl_mode(mon)) {
-        qerror_report_err(local_err);
-        error_free(local_err);
-        return -1;
-    }
-
-    error_free(local_err);
     monitor_printf(mon, "%s (%s) is encrypted.\n", bdrv_get_device_name(bs),
                    bdrv_get_encrypted_filename(bs));
 
@@ -5414,6 +5397,7 @@ int monitor_read_block_device_key(Monitor *mon, const char *device,
                                   BlockCompletionFunc *completion_cb,
                                   void *opaque)
 {
+    Error *err = NULL;
     BlockBackend *blk;
 
     blk = blk_by_name(device);
@@ -5422,7 +5406,16 @@ int monitor_read_block_device_key(Monitor *mon, const char *device,
         return -1;
     }
 
-    return monitor_read_bdrv_key_start(mon, blk_bs(blk), completion_cb, opaque);
+    bdrv_add_key(blk_bs(blk), NULL, &err);
+    if (err) {
+        error_free(err);
+        return monitor_read_bdrv_key_start(mon, blk_bs(blk), completion_cb, opaque);
+    }
+
+    if (completion_cb) {
+        completion_cb(opaque, 0);
+    }
+    return 0;
 }
 
 QemuOptsList qemu_mon_opts = {