[Qemu-devel] [PATCH 9/9] qapi: Add transaction support to dirty-bitmap-{add, disable}

[Fam Zheng <famz@redhat.com>]

This adds dirty-bitmap-add and dirty-bitmap-disable to transactions.
With this, user can stop a dirty bitmap, start backup of it, and start
another dirty bitmap atomically, so that the dirty bitmap is tracked
incrementally and we don't miss any write.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 blockdev.c       | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 qapi-schema.json |  4 +++-
 2 files changed, 71 insertions(+), 1 deletion(-)

diff --git a/blockdev.c b/blockdev.c
index 090a681..3a8fbf2 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1335,6 +1335,64 @@ static void drive_backup_abort(BlkTransactionState *common)
     }
 }
 
+static void dirty_bitmap_add_prepare(BlkTransactionState *common, Error **errp)
+{
+    DirtyBitmap *action;
+    Error *local_err = NULL;
+
+    action = common->action->dirty_bitmap_add;
+    qmp_dirty_bitmap_add(action->device, action->name, false, 0, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(errp, local_err);
+    }
+}
+
+static void dirty_bitmap_add_abort(BlkTransactionState *common)
+{
+    DirtyBitmap *action;
+    BdrvDirtyBitmap *bm;
+    BlockDriverState *bs;
+
+    action = common->action->dirty_bitmap_add;
+    bs = bdrv_find(action->device);
+    if (bs) {
+        bm = bdrv_find_dirty_bitmap(bs, action->name);
+        if (bm) {
+            bdrv_release_dirty_bitmap(bs, bm);
+        }
+    }
+}
+
+static void dirty_bitmap_disable_prepare(BlkTransactionState *common,
+                                         Error **errp)
+{
+    DirtyBitmap *action;
+    Error *local_err = NULL;
+
+    action = common->action->dirty_bitmap_disable;
+    qmp_dirty_bitmap_disable(action->device, action->name,
+                             false, 0, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(errp, local_err);
+    }
+}
+
+static void dirty_bitmap_disable_abort(BlkTransactionState *common)
+{
+    DirtyBitmap *action;
+    BdrvDirtyBitmap *bitmap;
+    BlockDriverState *bs;
+
+    action = common->action->dirty_bitmap_disable;
+    bs = bdrv_find(action->device);
+    if (bs) {
+        bitmap = bdrv_find_dirty_bitmap(bs, action->name);
+        if (bitmap) {
+            bdrv_enable_dirty_bitmap(bs, bitmap);
+        }
+    }
+}
+
 static void abort_prepare(BlkTransactionState *common, Error **errp)
 {
     error_setg(errp, "Transaction aborted using Abort action");
@@ -1367,6 +1425,16 @@ static const BdrvActionOps actions[] = {
         .prepare  = internal_snapshot_prepare,
         .abort = internal_snapshot_abort,
     },
+    [TRANSACTION_ACTION_KIND_DIRTY_BITMAP_ADD] = {
+        .instance_size = sizeof(BlkTransactionState),
+        .prepare = dirty_bitmap_add_prepare,
+        .abort = dirty_bitmap_add_abort,
+    },
+    [TRANSACTION_ACTION_KIND_DIRTY_BITMAP_DISABLE] = {
+        .instance_size = sizeof(BlkTransactionState),
+        .prepare = dirty_bitmap_disable_prepare,
+        .abort = dirty_bitmap_disable_abort,
+    },
 };
 
 /*
diff --git a/qapi-schema.json b/qapi-schema.json
index 8a81026..22cf010 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1843,7 +1843,9 @@
        'blockdev-snapshot-sync': 'BlockdevSnapshot',
        'drive-backup': 'DriveBackup',
        'abort': 'Abort',
-       'blockdev-snapshot-internal-sync': 'BlockdevSnapshotInternal'
+       'blockdev-snapshot-internal-sync': 'BlockdevSnapshotInternal',
+       'dirty-bitmap-add': 'DirtyBitmap',
+       'dirty-bitmap-disable': 'DirtyBitmap'
    } }
 
 ##
-- 
1.8.5.2