chore: include file name in the BackingFile

If the file cannot be found, it's not clear what file Firecracker is
referring to. Be explicit about what file it failed to find.

Signed-off-by: Pablo Barbáchano <[email protected]>

Author: pb8o

src/devices/src/virtio/block/device.rs

@@ -93,10 +93,10 @@ impl DiskProperties {
             .read(true)
             .write(!is_disk_read_only)
             .open(PathBuf::from(&disk_image_path))
-            .map_err(Error::BackingFile)?;
+            .map_err(|x| Error::BackingFile(x, disk_image_path.clone()))?;
         let disk_size = disk_image
             .seek(SeekFrom::End(0))
-            .map_err(Error::BackingFile)?;
+            .map_err(|x| Error::BackingFile(x, disk_image_path.clone()))?;
 
         // We only support disk size, which uses the first two words of the configuration space.
         // If the image is not a multiple of the sector size, the tail bits are not exposed.

src/devices/src/virtio/block/mod.rs

@@ -45,7 +45,7 @@ pub enum Error {
     // Error coming from the IO engine.
     FileEngine(io::Error),
     // Error manipulating the backing file.
-    BackingFile(std::io::Error),
+    BackingFile(std::io::Error, String),
     // Error opening eventfd.
     EventFd(std::io::Error),
     // Error creating an irqfd.

tests/integration_tests/functional/test_api.py

@@ -871,33 +871,36 @@ def _drive_patch(test_microvm):
     assert test_microvm.api_session.is_status_bad_request(response.status_code)
     assert "at least one property to patch: path_on_host, rate_limiter" in response.text
 
+    drive_path = "foo.bar"
+
     # Cannot patch drive permissions post boot.
     response = test_microvm.drive.patch(
-        drive_id="scratch", path_on_host="foo.bar", is_read_only=True
+        drive_id="scratch", path_on_host=drive_path, is_read_only=True
     )
     assert test_microvm.api_session.is_status_bad_request(response.status_code)
     assert "unknown field `is_read_only`" in response.text
 
     # Cannot patch io_engine post boot.
     response = test_microvm.drive.patch(
-        drive_id="scratch", path_on_host="foo.bar", io_engine="Sync"
+        drive_id="scratch", path_on_host=drive_path, io_engine="Sync"
     )
     assert test_microvm.api_session.is_status_bad_request(response.status_code)
     assert "unknown field `io_engine`" in response.text
 
     # Updates to `is_root_device` with a valid value are not allowed.
     response = test_microvm.drive.patch(
-        drive_id="scratch", path_on_host="foo.bar", is_root_device=False
+        drive_id="scratch", path_on_host=drive_path, is_root_device=False
     )
     assert test_microvm.api_session.is_status_bad_request(response.status_code)
     assert "unknown field `is_root_device`" in response.text
 
     # Updates to `path_on_host` with an invalid path are not allowed.
-    response = test_microvm.drive.patch(drive_id="scratch", path_on_host="foo.bar")
+    response = test_microvm.drive.patch(drive_id="scratch", path_on_host=drive_path)
     assert test_microvm.api_session.is_status_bad_request(response.status_code)
     assert (
         "Unable to patch the block device: BackingFile(Os { code: 2, "
-        'kind: NotFound, message: \\"No such file or directory\\" })' in response.text
+        f'kind: NotFound, message: \\"No such file or directory\\" }}, \\"{drive_path}\\")'
+        in response.text
     )
 
     fs = drive_tools.FilesystemFile(os.path.join(test_microvm.fsfiles, "scratch_new"))