qed: Add support for zero clusters

Zero clusters are similar to unallocated clusters except instead of reading
their value from a backing file when one is available, the cluster is always
read as zero.

This implements read support only.  At this stage, QED will never write a
zero cluster.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/block/qed.h b/block/qed.h
index 2925e37..3e1ab84 100644
--- a/block/qed.h
+++ b/block/qed.h
@@ -161,6 +161,7 @@ typedef struct {
 
 enum {
     QED_CLUSTER_FOUND,         /* cluster found */
+    QED_CLUSTER_ZERO,          /* zero cluster found */
     QED_CLUSTER_L2,            /* cluster missing in L2 */
     QED_CLUSTER_L1,            /* cluster missing in L1 */
 };
@@ -298,4 +299,29 @@ static inline bool qed_check_table_offset(BDRVQEDState *s, uint64_t offset)
            qed_check_cluster_offset(s, end_offset);
 }
 
+static inline bool qed_offset_is_cluster_aligned(BDRVQEDState *s,
+                                                 uint64_t offset)
+{
+    if (qed_offset_into_cluster(s, offset)) {
+        return false;
+    }
+    return true;
+}
+
+static inline bool qed_offset_is_unalloc_cluster(uint64_t offset)
+{
+    if (offset == 0) {
+        return true;
+    }
+    return false;
+}
+
+static inline bool qed_offset_is_zero_cluster(uint64_t offset)
+{
+    if (offset == 1) {
+        return true;
+    }
+    return false;
+}
+
 #endif /* BLOCK_QED_H */