qcow2-cache: Empty cache

Add a function for emptying a cache, i.e., flushing it and marking all
elements invalid.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

2 files changed, 20 insertions, 0 deletions

diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c
index 7bcae09a69..40a5a3fc39 100644
--- a/block/qcow2-cache.c
+++ b/block/qcow2-cache.c
@@ -202,6 +202,24 @@ void qcow2_cache_depends_on_flush(Qcow2Cache *c)
     c->depends_on_flush = true;
 }
 
+int qcow2_cache_empty(BlockDriverState *bs, Qcow2Cache *c)
+{
+    int ret, i;
+
+    ret = qcow2_cache_flush(bs, c);
+    if (ret < 0) {
+        return ret;
+    }
+
+    for (i = 0; i < c->size; i++) {
+        assert(c->entries[i].ref == 0);
+        c->entries[i].offset = 0;
+        c->entries[i].cache_hits = 0;
+    }
+
+    return 0;
+}
+
 static int qcow2_cache_find_entry_to_replace(Qcow2Cache *c)
 {
     int i;
diff --git a/block/qcow2.h b/block/qcow2.h
index 49eed828c5..35c822b8a6 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -478,6 +478,8 @@ int qcow2_cache_set_dependency(BlockDriverState *bs, Qcow2Cache *c,
     Qcow2Cache *dependency);
 void qcow2_cache_depends_on_flush(Qcow2Cache *c);
 
+int qcow2_cache_empty(BlockDriverState *bs, Qcow2Cache *c);
+
 int qcow2_cache_get(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
     void **table);
 int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,