block: stack unplug

PATCH New Shaohua Li 1 participant 1 message Jul 10, 2012 Block layer

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Shaohua Li

author

2012-07-10 05:02 UTC #0 lore raw

PATCH 1/1 block: stack unplug

MD raid1 prepares to dispatch request in unplug callback. If make_request in low level queue also uses unplug callback to dispatch request, the low level queue's unplug callback will not be called. Recheck the callback list helps this case.

Signed-off-by Shaohua Li <[email protected]>

block/blk-core.c +7 -8

index 93eb3e4..700cbfa 100644
@@ -2900,17 +2900,16 @@ static void flush_plug_callbacks(struct blk_plug *plug)
 {
 	LIST_HEAD(callbacks);
 
-	if (list_empty(&plug->cb_list))
-		return;
-
-	list_splice_init(&plug->cb_list, &callbacks);
+	while (!list_empty(&plug->cb_list)) {
+		list_splice_init(&plug->cb_list, &callbacks);
 
-	while (!list_empty(&callbacks)) {
-		struct blk_plug_cb *cb = list_first_entry(&callbacks,
+		while (!list_empty(&callbacks)) {
+			struct blk_plug_cb *cb = list_first_entry(&callbacks,
 							  struct blk_plug_cb,
 							  list);
-		list_del(&cb->list);
-		cb->callback(cb);
+			list_del(&cb->list);
+			cb->callback(cb);
+		}
 	}
 }