block: introduce dirty_bitmap_mutex
It protects only the list of dirty bitmaps; in the next patch we will
also protect their content.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170605123908.18777-15-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
diff --git a/include/block/block_int.h b/include/block/block_int.h
index ae74df9..21cb65b 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -609,6 +609,11 @@
uint64_t write_threshold_offset;
NotifierWithReturn write_threshold_notifier;
+ /* Writing to the list requires the BQL _and_ the dirty_bitmap_mutex.
+ * Reading from the list can be done with either the BQL or the
+ * dirty_bitmap_mutex. Modifying a bitmap requires the AioContext
+ * lock. */
+ QemuMutex dirty_bitmap_mutex;
QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps;
/* Offset after the highest byte written to */
