block/null-{co,aio}: Implement get_block_status()

Signed-off-by: Max Reitz <mreitz@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/null.c

@@ -205,6 +205,24 @@ static int null_reopen_prepare(BDRVReopenState *reopen_state,
     return 0;
 }
 
+static int64_t coroutine_fn null_co_get_block_status(BlockDriverState *bs,
+                                                     int64_t sector_num,
+                                                     int nb_sectors, int *pnum,
+                                                     BlockDriverState **file)
+{
+    BDRVNullState *s = bs->opaque;
+    off_t start = sector_num * BDRV_SECTOR_SIZE;
+
+    *pnum = nb_sectors;
+    *file = bs;
+
+    if (s->read_zeroes) {
+        return BDRV_BLOCK_OFFSET_VALID | start | BDRV_BLOCK_ZERO;
+    } else {
+        return BDRV_BLOCK_OFFSET_VALID | start;
+    }
+}
+
 static BlockDriver bdrv_null_co = {
     .format_name            = "null-co",
     .protocol_name          = "null-co",
@@ -218,6 +236,8 @@ static BlockDriver bdrv_null_co = {
     .bdrv_co_writev         = null_co_writev,
     .bdrv_co_flush_to_disk  = null_co_flush,
     .bdrv_reopen_prepare    = null_reopen_prepare,
+
+    .bdrv_co_get_block_status   = null_co_get_block_status,
 };
 
 static BlockDriver bdrv_null_aio = {
@@ -233,6 +253,8 @@ static BlockDriver bdrv_null_aio = {
     .bdrv_aio_writev        = null_aio_writev,
     .bdrv_aio_flush         = null_aio_flush,
     .bdrv_reopen_prepare    = null_reopen_prepare,
+
+    .bdrv_co_get_block_status   = null_co_get_block_status,
 };
 
 static void bdrv_null_init(void)