block: used bytes reporting regression test

Signed-off-by: Iulian Barbu <[email protected]>
Signed-off-by: Alin Dima <[email protected]>

Author: Iulian Barbu

tests/integration_tests/functional/test_drives.py

@@ -11,6 +11,8 @@
 import host_tools.drive as drive_tools
 import host_tools.network as net_tools  # pylint: disable=import-error
 
+MB = 1024 * 1024
+
 
 def test_rescan_file(test_microvm_with_ssh, network_config):
     """Verify that rescan works with a file-backed virtio device."""
@@ -24,9 +26,11 @@ def test_rescan_file(test_microvm_with_ssh, network_config):
 
     _tap, _, _ = test_microvm_with_ssh.ssh_network_config(network_config, '1')
 
+    block_size = 2
     # Add a scratch block device.
     fs = drive_tools.FilesystemFile(
-        os.path.join(test_microvm.fsfiles, 'scratch')
+        os.path.join(test_microvm.fsfiles, 'scratch'),
+        size=block_size
     )
     response = test_microvm.drive.put(
         drive_id='scratch',
@@ -42,8 +46,16 @@ def test_rescan_file(test_microvm_with_ssh, network_config):
 
     _check_scratch_size(ssh_connection, fs.size())
 
-    # Resize the filesystem from 256 MiB (default) to 512 MiB.
-    fs.resize(512)
+    # Check if reading from the entire disk results in a file of the same size
+    # or errors out, after a truncate on the host.
+    truncated_size = block_size//2
+    utils.run_cmd(f"truncate --size {truncated_size}M {fs.path}")
+    block_copy_name = "dev_vdb_copy"
+    _, _, stderr = ssh_connection.execute_command(
+        f"dd if=/dev/vdb of={block_copy_name} bs=1M count={block_size}")
+    assert "dd: error reading '/dev/vdb': Input/output error" in stderr.read()
+    _check_file_size(ssh_connection, f'{block_copy_name}',
+                     truncated_size * MB)
 
     response = test_microvm.drive.patch(
         drive_id='scratch',
@@ -300,6 +312,15 @@ def _check_scratch_size(ssh_connection, size):
     assert stdout.readline().strip() == str(size)
 
 
+def _check_file_size(ssh_connection, dev_path, size):
+    _, stdout, stderr = ssh_connection.execute_command(
+        'stat --format=%s {}'.format(dev_path)
+    )
+
+    assert stderr.read() == ''
+    assert stdout.readline().strip() == str(size)
+
+
 def _process_blockdev_output(blockdev_out, assert_dict, keys_array):
     blockdev_out_lines = blockdev_out.splitlines()