[PATCH v2 1/8] block: prepare write threshold code for thread safety

[Emanuele Giuseppe Esposito <eesposit@redhat.com>]

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 block/write-threshold.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/block/write-threshold.c b/block/write-threshold.c
index 85b78dc2a9..63040fa4f2 100644
--- a/block/write-threshold.c
+++ b/block/write-threshold.c
@@ -37,18 +37,22 @@ static void write_threshold_disable(BlockDriverState *bs)
     }
 }
 
+static uint64_t treshold_overage(const BdrvTrackedRequest *req,
+                                uint64_t thres)
+{
+    if (thres > 0 && req->offset + req->bytes > thres) {
+        return req->offset + req->bytes - thres;
+    } else {
+        return 0;
+    }
+}
+
 uint64_t bdrv_write_threshold_exceeded(const BlockDriverState *bs,
                                        const BdrvTrackedRequest *req)
 {
-    if (bdrv_write_threshold_is_set(bs)) {
-        if (req->offset > bs->write_threshold_offset) {
-            return (req->offset - bs->write_threshold_offset) + req->bytes;
-        }
-        if ((req->offset + req->bytes) > bs->write_threshold_offset) {
-            return (req->offset + req->bytes) - bs->write_threshold_offset;
-        }
-    }
-    return 0;
+    uint64_t thres = bdrv_write_threshold_get(bs);
+
+    return treshold_overage(req, thres);
 }
 
 static int coroutine_fn before_write_notify(NotifierWithReturn *notifier,
@@ -56,14 +60,14 @@ static int coroutine_fn before_write_notify(NotifierWithReturn *notifier,
 {
     BdrvTrackedRequest *req = opaque;
     BlockDriverState *bs = req->bs;
-    uint64_t amount = 0;
+    uint64_t thres = bdrv_write_threshold_get(bs);
+    uint64_t amount = treshold_overage(req, thres);
 
-    amount = bdrv_write_threshold_exceeded(bs, req);
     if (amount > 0) {
         qapi_event_send_block_write_threshold(
             bs->node_name,
             amount,
-            bs->write_threshold_offset);
+            thres);
 
         /* autodisable to avoid flooding the monitor */
         write_threshold_disable(bs);
-- 
2.30.2