[PATCH v2] block-backend: per-device throttling of BLOCK_IO_ERROR reports

[Vladimir Sementsov-Ogievskiy]

From: Leonid Kaplan <x...@yandex-team.ru>

BLOCK_IO_ERROR events comes from guest, so we must throttle them.
We still want per-device throttling, so let's use device id as a key.

Signed-off-by: Leonid Kaplan <x...@yandex-team.ru>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@yandex-team.ru>
---

v2: add Note: to QAPI doc

 monitor/monitor.c    | 10 ++++++++++
 qapi/block-core.json |  2 ++
 2 files changed, 12 insertions(+)

diff --git a/monitor/monitor.c b/monitor/monitor.c
index 01ede1babd..ad0243e9d7 100644
--- a/monitor/monitor.c
+++ b/monitor/monitor.c
@@ -309,6 +309,7 @@ int error_printf_unless_qmp(const char *fmt, ...)
 static MonitorQAPIEventConf monitor_qapi_event_conf[QAPI_EVENT__MAX] = {
     /* Limit guest-triggerable events to 1 per second */
     [QAPI_EVENT_RTC_CHANGE]        = { 1000 * SCALE_MS },
+    [QAPI_EVENT_BLOCK_IO_ERROR]    = { 1000 * SCALE_MS },
     [QAPI_EVENT_WATCHDOG]          = { 1000 * SCALE_MS },
     [QAPI_EVENT_BALLOON_CHANGE]    = { 1000 * SCALE_MS },
     [QAPI_EVENT_QUORUM_REPORT_BAD] = { 1000 * SCALE_MS },
@@ -498,6 +499,10 @@ static unsigned int qapi_event_throttle_hash(const void 
*key)
         hash += g_str_hash(qdict_get_str(evstate->data, "qom-path"));
     }
 
+    if (evstate->event == QAPI_EVENT_BLOCK_IO_ERROR) {
+        hash += g_str_hash(qdict_get_str(evstate->data, "device"));
+    }
+
     return hash;
 }
 
@@ -525,6 +530,11 @@ static gboolean qapi_event_throttle_equal(const void *a, 
const void *b)
                        qdict_get_str(evb->data, "qom-path"));
     }
 
+    if (eva->event == QAPI_EVENT_BLOCK_IO_ERROR) {
+        return !strcmp(qdict_get_str(eva->data, "device"),
+                       qdict_get_str(evb->data, "device"));
+    }
+
     return TRUE;
 }
 
diff --git a/qapi/block-core.json b/qapi/block-core.json
index ca390c5700..32c2c2f030 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -5559,6 +5559,8 @@
 # Note: If action is "stop", a STOP event will eventually follow the
 #     BLOCK_IO_ERROR event
 #
+# Note: This event is rate-limited.
+#
 # Since: 0.13
 #
 # Example:
-- 
2.34.1