QMP: query-status: Add 'io-status' key

Contains the I/O status for the given device. The key is only present
if the device supports it and the VM is configured to stop on errors.

Please, check the documentation being added in this commit for more
information.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block.c

@@ -1893,6 +1893,12 @@ void bdrv_info_print(Monitor *mon, const QObject *data)
     qlist_iter(qobject_to_qlist(data), bdrv_print_dict, mon);
 }
 
+static const char *const io_status_name[BDRV_IOS_MAX] = {
+    [BDRV_IOS_OK] = "ok",
+    [BDRV_IOS_FAILED] = "failed",
+    [BDRV_IOS_ENOSPC] = "nospace",
+};
+
 void bdrv_info(Monitor *mon, QObject **ret_data)
 {
     QList *bs_list;
@@ -1915,6 +1921,12 @@ void bdrv_info(Monitor *mon, QObject **ret_data)
             qdict_put(bs_dict, "tray-open",
                       qbool_from_int(bdrv_dev_is_tray_open(bs)));
         }
+
+        if (bdrv_iostatus_is_enabled(bs)) {
+            qdict_put(bs_dict, "io-status",
+                      qstring_from_str(io_status_name[bs->iostatus]));
+        }
+
         if (bs->drv) {
             QObject *obj;
 

qmp-commands.hx

@@ -1154,6 +1154,10 @@ Each json-object contain the following:
                                 "tftp", "vdi", "vmdk", "vpc", "vvfat"
          - "backing_file": backing file name (json-string, optional)
          - "encrypted": true if encrypted, false otherwise (json-bool)
+- "io-status": I/O operation status, only present if the device supports it
+               and the VM is configured to stop on errors. It's always reset
+               to "ok" when the "cont" command is issued (json_string, optional)
+             - Possible values: "ok", "failed", "nospace"
 
 Example:
 
@@ -1161,6 +1165,7 @@ Example:
 <- {
       "return":[
          {
+            "io-status": "ok",
             "device":"ide0-hd0",
             "locked":false,
             "removable":false,
@@ -1173,6 +1178,7 @@ Example:
             "type":"unknown"
          },
          {
+            "io-status": "ok",
             "device":"ide1-cd0",
             "locked":false,
             "removable":true,