block: Add BlockDriver.bdrv_check_ext_snapshot.

This field is used by blkverify to disable external snapshots creation.
It will also be used by block filters like quorum to disable external
snapshot creation.

Signed-off-by: Benoit Canet <benoit@irqsave.net>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/block.c b/block.c
index d86efad867..beea0274f8 100644
--- a/block.c
+++ b/block.c
@@ -4647,3 +4647,22 @@ int bdrv_amend_options(BlockDriverState *bs, QEMUOptionParameter *options)
     }
     return bs->drv->bdrv_amend_options(bs, options);
 }
+
+ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *bs)
+{
+    if (bs->drv->bdrv_check_ext_snapshot) {
+        return bs->drv->bdrv_check_ext_snapshot(bs);
+    }
+
+    if (bs->file && bs->file->drv && bs->file->drv->bdrv_check_ext_snapshot) {
+        return bs->file->drv->bdrv_check_ext_snapshot(bs);
+    }
+
+    /* external snapshots are allowed by default */
+    return EXT_SNAPSHOT_ALLOWED;
+}
+
+ExtSnapshotPerm bdrv_check_ext_snapshot_forbidden(BlockDriverState *bs)
+{
+    return EXT_SNAPSHOT_FORBIDDEN;
+}