[Qemu-devel] [RFC V5 12/36] qcow2: make the deduplication forget a cluster hash when a cluster is to dedupe

["Benoît Canet" <benoit@irqsave.net>]

Signed-off-by: Benoit Canet <benoit@irqsave.net>
---
 block/qcow2-cluster.c |   11 +++++++++--
 block/qcow2-dedup.c   |    8 +++++++-
 block/qcow2.h         |    2 ++
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index ef91216..5b1d20d 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -710,6 +710,7 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
 
     for (i = 0; i < m->nb_clusters; i++) {
         uint64_t flags = 0;
+        uint64_t offset = cluster_offset + (i << s->cluster_bits);
         /* if two concurrent writes happen to the same unallocated cluster
 	 * each write allocates separate cluster and writes data concurrently.
 	 * The first one to complete updates l2 table with pointer to its
@@ -722,8 +723,14 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
         flags = m->oflag_copied ? QCOW_OFLAG_COPIED : 0;
         flags |= m->to_deduplicate ? QCOW_OFLAG_TO_DEDUP : 0;
 
-        l2_table[l2_index + i] = cpu_to_be64((cluster_offset +
-                    (i << s->cluster_bits)) | flags);
+        l2_table[l2_index + i] = cpu_to_be64(offset | flags);
+
+        /* make the deduplication forget the cluster to avoid making
+         * the dedup pointing to a cluster that has changed on it's back.
+         */
+        if (m->to_deduplicate) {
+            qcow2_dedup_forget_cluster_by_sector(bs, offset >> 9);
+        }
      }
 
 
diff --git a/block/qcow2-dedup.c b/block/qcow2-dedup.c
index 3d512e5..7049bd8 100644
--- a/block/qcow2-dedup.c
+++ b/block/qcow2-dedup.c
@@ -824,7 +824,7 @@ static void qcow2_remove_hash_node(BlockDriverState *bs,
  * @physical_sect: The physical sector of the cluster corresponding to the hash
  */
 static void qcow2_remove_hash_node_by_sector(BlockDriverState *bs,
-                                            uint64_t physical_sect)
+                                             uint64_t physical_sect)
 {
     BDRVQcowState *s = bs->opaque;
     QCowHashNode *hash_node;
@@ -838,6 +838,12 @@ static void qcow2_remove_hash_node_by_sector(BlockDriverState *bs,
     qcow2_remove_hash_node(bs, hash_node);
 }
 
+void qcow2_dedup_forget_cluster_by_sector(BlockDriverState *bs,
+                                          uint64_t physical_sect)
+{
+    qcow2_remove_hash_node_by_sector(bs, physical_sect);
+}
+
 /* This function store a hash information to disk and RAM
  *
  * @hash:           the QCowHash to process
diff --git a/block/qcow2.h b/block/qcow2.h
index da7e57e..bc1ba33 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -469,6 +469,8 @@ int qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table);
 
 /* qcow2-dedup.c functions */
 bool qcow2_must_deduplicate(BlockDriverState *bs);
+void qcow2_dedup_forget_cluster_by_sector(BlockDriverState *bs,
+                                          uint64_t physical_sect);
 int qcow2_dedup_read_missing_and_concatenate(BlockDriverState *bs,
                                              QEMUIOVector *qiov,
                                              uint64_t sector,
-- 
1.7.10.4