[PATCH 2/2] qapi: Fix qmp_block_set_io_throttle blocked for too long

[zoudongjie via]

From: Zhu Yangyang <zhuyangyan...@huawei.com>

bdrv_drained_begin() is blocked for a long time when network storage is used
and the network link has just failed.
Therefore, the timeout period is set here.

Signed-off-by: Zhu Yangyang <zhuyangyan...@huawei.com>
---
 block/block-backend.c                       | 14 +++++++++++++-
 block/qapi-system.c                         |  7 ++++++-
 include/system/block-backend-global-state.h |  1 +
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/block/block-backend.c b/block/block-backend.c
index 9288f7e1c6..409d4559c3 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -2691,20 +2691,32 @@ void blk_set_io_limits(BlockBackend *blk, 
ThrottleConfig *cfg)
 }
 
 void blk_io_limits_disable(BlockBackend *blk)
+{
+    blk_io_limits_disable_timeout(blk, -1);
+}
+
+int blk_io_limits_disable_timeout(BlockBackend *blk, int64_t timeout_ms)
 {
     BlockDriverState *bs = blk_bs(blk);
     ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
+    int ret = 0;
+
     assert(tgm->throttle_state);
     GLOBAL_STATE_CODE();
     if (bs) {
         bdrv_ref(bs);
-        bdrv_drained_begin(bs);
+        ret = bdrv_drained_begin_timeout(bs, timeout_ms);
+        if (ret < 0) {
+            goto out;
+        }
     }
     throttle_group_unregister_tgm(tgm);
+out:
     if (bs) {
         bdrv_drained_end(bs);
         bdrv_unref(bs);
     }
+    return ret;
 }
 
 /* should be called before blk_set_io_limits if a limit is set */
diff --git a/block/qapi-system.c b/block/qapi-system.c
index 54b7409b2b..96fa8e5e51 100644
--- a/block/qapi-system.c
+++ b/block/qapi-system.c
@@ -39,6 +39,8 @@
 #include "system/block-backend.h"
 #include "system/blockdev.h"
 
+#define QMP_BLOCKING_TIMEOUT 5000 /* ms */
+
 static BlockBackend *qmp_get_blk(const char *blk_name, const char *qdev_id,
                                  Error **errp)
 {
@@ -502,7 +504,10 @@ void qmp_block_set_io_throttle(BlockIOThrottle *arg, Error 
**errp)
         blk_set_io_limits(blk, &cfg);
     } else if (blk_get_public(blk)->throttle_group_member.throttle_state) {
         /* If all throttling settings are set to 0, disable I/O limits */
-        blk_io_limits_disable(blk);
+        if (blk_io_limits_disable_timeout(blk, QMP_BLOCKING_TIMEOUT) < 0) {
+            error_setg(errp, "Blk io limits disable timeout");
+            return;
+        }
     }
 }
 
diff --git a/include/system/block-backend-global-state.h 
b/include/system/block-backend-global-state.h
index 9cc9b008ec..e55ea9dc64 100644
--- a/include/system/block-backend-global-state.h
+++ b/include/system/block-backend-global-state.h
@@ -111,6 +111,7 @@ int blk_probe_geometry(BlockBackend *blk, HDGeometry *geo);
 
 void blk_set_io_limits(BlockBackend *blk, ThrottleConfig *cfg);
 void blk_io_limits_disable(BlockBackend *blk);
+int blk_io_limits_disable_timeout(BlockBackend *blk, int64_t timeout_ms);
 void blk_io_limits_enable(BlockBackend *blk, const char *group);
 void blk_io_limits_update_group(BlockBackend *blk, const char *group);
 void blk_set_force_allow_inactivate(BlockBackend *blk);
-- 
2.33.0