block drivers: add discard/write_zeroes properties to bdrv_get_info implementation

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

block/qcow2.c

@@ -1893,6 +1893,8 @@ static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs)
 static int qcow2_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 {
     BDRVQcowState *s = bs->opaque;
+    bdi->unallocated_blocks_are_zero = true;
+    bdi->can_write_zeroes_with_unmap = (s->qcow_version >= 3);
     bdi->cluster_size = s->cluster_size;
     bdi->vm_state_offset = qcow2_vm_state_offset(s);
     return 0;

block/qed.c

@@ -1475,6 +1475,8 @@ static int bdrv_qed_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
     memset(bdi, 0, sizeof(*bdi));
     bdi->cluster_size = s->header.cluster_size;
     bdi->is_dirty = s->header.features & QED_F_NEED_CHECK;
+    bdi->unallocated_blocks_are_zero = true;
+    bdi->can_write_zeroes_with_unmap = true;
     return 0;
 }
 

block/vdi.c

@@ -331,6 +331,7 @@ static int vdi_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
     logout("\n");
     bdi->cluster_size = s->block_size;
     bdi->vm_state_offset = 0;
+    bdi->unallocated_blocks_are_zero = true;
     return 0;
 }
 

block/vhdx.c

@@ -1049,6 +1049,9 @@ static int vhdx_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 
     bdi->cluster_size = s->block_size;
 
+    bdi->unallocated_blocks_are_zero =
+        (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) == 0;
+
     return 0;
 }
 

block/vpc.c

@@ -464,6 +464,7 @@ static int vpc_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
         bdi->cluster_size = s->block_size;
     }
 
+    bdi->unallocated_blocks_are_zero = true;
     return 0;
 }