[Qemu-devel] [PATCH 6/8] qcow2: add autoclear bit for dirty bitmaps

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

From: Vladimir Sementsov-Ogievskiy <vsementsov@parallels.com>

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/qcow2-dirty-bitmap.c |  5 +++++
 block/qcow2.c              | 13 +++++++++++--
 block/qcow2.h              |  9 +++++++++
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/block/qcow2-dirty-bitmap.c b/block/qcow2-dirty-bitmap.c
index db83112..686a121 100644
--- a/block/qcow2-dirty-bitmap.c
+++ b/block/qcow2-dirty-bitmap.c
@@ -188,6 +188,11 @@ static int qcow2_write_dirty_bitmaps(BlockDriverState *bs)
 
     s->dirty_bitmaps_offset = dirty_bitmaps_offset;
     s->dirty_bitmaps_size = dirty_bitmaps_size;
+    if (s->nb_dirty_bitmaps > 0) {
+        s->autoclear_features |= QCOW2_AUTOCLEAR_DIRTY_BITMAPS;
+    } else {
+        s->autoclear_features &= ~QCOW2_AUTOCLEAR_DIRTY_BITMAPS;
+    }
     ret = qcow2_update_header(bs);
     if (ret < 0) {
         fprintf(stderr, "Could not update qcow2 header\n");
diff --git a/block/qcow2.c b/block/qcow2.c
index 406e55d..f85a55a 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -182,6 +182,14 @@ static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset,
                 return ret;
             }
 
+            if (!(s->autoclear_features & QCOW2_AUTOCLEAR_DIRTY_BITMAPS) &&
+                s->nb_dirty_bitmaps > 0) {
+                ret = qcow2_delete_all_dirty_bitmaps(bs, errp);
+                if (ret < 0) {
+                    return ret;
+                }
+            }
+
 #ifdef DEBUG_EXT
             printf("Qcow2: Got dirty bitmaps extension:"
                    " offset=%" PRIu64 " nb_bitmaps=%" PRIu32 "\n",
@@ -928,8 +936,9 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     /* Clear unknown autoclear feature bits */
-    if (!bs->read_only && !(flags & BDRV_O_INCOMING) && s->autoclear_features) {
-        s->autoclear_features = 0;
+    if (!bs->read_only && !(flags & BDRV_O_INCOMING) &&
+        (s->autoclear_features & ~QCOW2_AUTOCLEAR_MASK)) {
+        s->autoclear_features |= QCOW2_AUTOCLEAR_MASK;
         ret = qcow2_update_header(bs);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Could not update qcow2 header");
diff --git a/block/qcow2.h b/block/qcow2.h
index b5e576c..14bd6f9 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -215,6 +215,15 @@ enum {
     QCOW2_COMPAT_FEAT_MASK            = QCOW2_COMPAT_LAZY_REFCOUNTS,
 };
 
+/* Autoclear feature bits */
+enum {
+    QCOW2_AUTOCLEAR_DIRTY_BITMAPS_BITNR = 0,
+    QCOW2_AUTOCLEAR_DIRTY_BITMAPS       =
+        1 << QCOW2_AUTOCLEAR_DIRTY_BITMAPS_BITNR,
+
+    QCOW2_AUTOCLEAR_MASK                = QCOW2_AUTOCLEAR_DIRTY_BITMAPS,
+};
+
 enum qcow2_discard_type {
     QCOW2_DISCARD_NEVER = 0,
     QCOW2_DISCARD_ALWAYS,
-- 
1.9.1