block: vhdx: Flatten internal and worker modules

Remove the internal and worker submodule layers from the VHDX format
directory. The bat, header, io, and metadata parsers move up as
direct children, internal/mod.rs becomes parser.rs, and the sync
backend moves up as engine_sync.rs. The declaration only
worker/mod.rs is dropped.

The public types are surfaced at the vhdx module level, so callers
use block::formats::vhdx instead of reaching into the internal
module.

Assisted-by: Claude:Opus-4.8
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>

block/src/formats/vhdx/bat.rs

@@ -14,17 +14,17 @@ use super::metadata::DiskSpec;
 use crate::aligned_file::AlignedFile;
 
 // Payload BAT Entry States
-pub const PAYLOAD_BLOCK_NOT_PRESENT: u64 = 0;
+pub(super) const PAYLOAD_BLOCK_NOT_PRESENT: u64 = 0;
-pub const PAYLOAD_BLOCK_UNDEFINED: u64 = 1;
+pub(super) const PAYLOAD_BLOCK_UNDEFINED: u64 = 1;
-pub const PAYLOAD_BLOCK_ZERO: u64 = 2;
+pub(super) const PAYLOAD_BLOCK_ZERO: u64 = 2;
-pub const PAYLOAD_BLOCK_UNMAPPED: u64 = 3;
+pub(super) const PAYLOAD_BLOCK_UNMAPPED: u64 = 3;
-pub const PAYLOAD_BLOCK_FULLY_PRESENT: u64 = 6;
+pub(super) const PAYLOAD_BLOCK_FULLY_PRESENT: u64 = 6;
-pub const PAYLOAD_BLOCK_PARTIALLY_PRESENT: u64 = 7;
+pub(super) const PAYLOAD_BLOCK_PARTIALLY_PRESENT: u64 = 7;
 
 // Mask for the BAT state
-pub const BAT_STATE_BIT_MASK: u64 = 0x07;
+pub(super) const BAT_STATE_BIT_MASK: u64 = 0x07;
 // Mask for the offset within the file in units of 1 MB
-pub const BAT_FILE_OFF_MASK: u64 = 0xFFFFFFFFFFF00000;
+pub(super) const BAT_FILE_OFF_MASK: u64 = 0xFFFFFFFFFFF00000;
 
 #[sorted]
 #[derive(Error, Debug)]
@@ -39,14 +39,14 @@ pub enum VhdxBatError {
     WriteBat(#[source] io::Error),
 }
 
-pub type Result<T> = result::Result<T, VhdxBatError>;
+pub(super) type Result<T> = result::Result<T, VhdxBatError>;
 
 #[derive(Default, Clone, Debug)]
-pub struct BatEntry(pub u64);
+pub(super) struct BatEntry(pub u64);
 
 impl BatEntry {
     // Read all BAT entries presented on the disk and insert them to a vector
-    pub fn collect_bat_entries(
+    pub(super) fn collect_bat_entries(
         f: &AlignedFile,
         disk_spec: &DiskSpec,
         bat_entry: &RegionTableEntry,
@@ -79,7 +79,7 @@ impl BatEntry {
     }
 
     // Routine for writing BAT entries to the disk
-    pub fn write_bat_entries(
+    pub(super) fn write_bat_entries(
         f: &AlignedFile,
         bat_offset: u64,
         bat_entries: &[BatEntry],

block/src/formats/vhdx/engine_sync.rs

@@ -11,9 +11,9 @@ use std::sync::{Arc, Mutex};
 use vmm_sys_util::eventfd::EventFd;
 
 use crate::async_io::{AsyncIo, AsyncIoCompletion, AsyncIoError, AsyncIoOperation, AsyncIoResult};
-use crate::formats::vhdx::internal::Vhdx;
+use crate::formats::vhdx::Vhdx;
 
-pub struct VhdxSync {
+pub(super) struct VhdxSync {
     vhdx_file: Arc<Mutex<Vhdx>>,
     eventfd: EventFd,
     completion_list: VecDeque<AsyncIoCompletion>,
@@ -21,7 +21,7 @@ pub struct VhdxSync {
 }
 
 impl VhdxSync {
-    pub fn new(vhdx_file: Arc<Mutex<Vhdx>>, size: u64) -> Self {
+    pub(super) fn new(vhdx_file: Arc<Mutex<Vhdx>>, size: u64) -> Self {
         VhdxSync {
             vhdx_file,
             eventfd: EventFd::new(libc::EFD_NONBLOCK)
@@ -120,7 +120,7 @@ mod tests {
 
     use super::*;
     use crate::async_io::{AsyncIo, AsyncIoError, AsyncIoOperation, OwnedIoBuffer};
-    use crate::formats::vhdx::internal::Vhdx;
+    use crate::formats::vhdx::Vhdx;
     use crate::formats::vhdx::test_util::create_dynamic_vhdx;
 
     fn make_vhdx_sync(tf: &TempFile) -> (VhdxSync, u64) {

block/src/formats/vhdx/header.rs

@@ -21,7 +21,7 @@ const REGION_SIGN: u32 = 0x6967_6572; // "regi"
 const FILE_START: u64 = 0; // The first element
 const HEADER_1_START: u64 = 64 * 1024; // Header 1 start in Bytes
 const HEADER_2_START: u64 = 128 * 1024; // Header 2 start in Bytes
-pub const REGION_TABLE_1_START: u64 = 192 * 1024; // Region 1 start in Bytes
+pub(super) const REGION_TABLE_1_START: u64 = 192 * 1024; // Region 1 start in Bytes
 const REGION_TABLE_2_START: u64 = 256 * 1024; // Region 2 start in Bytes
 
 const HEADER_SIZE: u64 = 4 * 1024; // Each header is 64 KiB, but only first 4 kiB contains info
@@ -84,16 +84,16 @@ pub enum VhdxHeaderError {
     WriteHeader(#[source] io::Error),
 }
 
-pub type Result<T> = result::Result<T, VhdxHeaderError>;
+pub(super) type Result<T> = result::Result<T, VhdxHeaderError>;
 
 #[derive(Clone, Debug)]
-pub struct FileTypeIdentifier {
+pub(super) struct FileTypeIdentifier {
     pub _signature: u64,
 }
 
 impl FileTypeIdentifier {
     /// Reads the File Type Identifier structure from a reference VHDx file
-    pub fn new(f: &AlignedFile) -> Result<FileTypeIdentifier> {
+    pub(super) fn new(f: &AlignedFile) -> Result<FileTypeIdentifier> {
         let mut buf = [0u8; size_of::<u64>()];
         f.read_exact_at(&mut buf, FILE_START)
             .map_err(VhdxHeaderError::ReadFileTypeIdentifier)?;
@@ -108,7 +108,7 @@ impl FileTypeIdentifier {
 
 #[repr(C, packed)]
 #[derive(Clone, Copy, Debug, FromBytes, Immutable, IntoBytes)]
-pub struct Header {
+pub(super) struct Header {
     pub signature: u32,
     pub checksum: u32,
     pub sequence_number: u64,
@@ -123,7 +123,7 @@ pub struct Header {
 
 impl Header {
     /// Reads the Header structure from a reference VHDx file
-    pub fn new(f: &AlignedFile, start: u64) -> Result<Header> {
+    pub(super) fn new(f: &AlignedFile, start: u64) -> Result<Header> {
         // Read the whole header into a buffer. We will need it for
         // calculating checksum.
         let mut buffer = [0; HEADER_SIZE as usize];
@@ -199,7 +199,7 @@ struct RegionTableHeader {
 
 impl RegionTableHeader {
     /// Reads the Region Table Header structure from a reference VHDx file
-    pub fn new(f: &AlignedFile, start: u64) -> Result<RegionTableHeader> {
+    pub(crate) fn new(f: &AlignedFile, start: u64) -> Result<RegionTableHeader> {
         // Read the whole header into a buffer. We will need it for calculating
         // checksum.
         let mut buffer = [0u8; REGION_SIZE as usize];
@@ -234,7 +234,7 @@ fn ranges_overlap(a_start: u64, a_end: u64, b_start: u64, b_end: u64) -> bool {
     a_start < b_end && b_start < a_end
 }
 
-pub struct RegionInfo {
+pub(super) struct RegionInfo {
     pub bat_entry: RegionTableEntry,
     pub mdr_entry: RegionTableEntry,
     pub region_entries: BTreeMap<u64, u64>,
@@ -243,7 +243,7 @@ pub struct RegionInfo {
 impl RegionInfo {
     /// Collect all entries in a BTreeMap from the Region Table and identifies
     /// BAT and metadata regions
-    pub fn new(f: &AlignedFile, region_start: u64, entry_count: u32) -> Result<RegionInfo> {
+    pub(super) fn new(f: &AlignedFile, region_start: u64, entry_count: u32) -> Result<RegionInfo> {
         let mut bat_entry: Option<RegionTableEntry> = None;
         let mut mdr_entry: Option<RegionTableEntry> = None;
 
@@ -321,7 +321,7 @@ impl RegionInfo {
 
 #[repr(C, packed)]
 #[derive(Clone, Copy, Debug, FromBytes)]
-pub struct RegionTableEntry {
+pub(super) struct RegionTableEntry {
     guid: [u8; 16],
     pub file_offset: u64,
     pub length: u32,
@@ -335,7 +335,7 @@ enum HeaderNo {
 
 /// Contains the information from the header of a VHDx file
 #[derive(Clone, Debug)]
-pub struct VhdxHeader {
+pub(super) struct VhdxHeader {
     _file_type_identifier: FileTypeIdentifier,
     header_1: Header,
     header_2: Header,
@@ -345,7 +345,7 @@ pub struct VhdxHeader {
 
 impl VhdxHeader {
     /// Creates a VhdxHeader from a reference to a file
-    pub fn new(f: &AlignedFile) -> Result<VhdxHeader> {
+    pub(super) fn new(f: &AlignedFile) -> Result<VhdxHeader> {
         Ok(VhdxHeader {
             _file_type_identifier: FileTypeIdentifier::new(f)?,
             header_1: Header::new(f, HEADER_1_START)?,
@@ -415,14 +415,14 @@ impl VhdxHeader {
         VhdxHeader::update_header(f, Ok(header_1), Ok(header_2), guid)
     }
 
-    pub fn update(&mut self, f: &AlignedFile) -> Result<()> {
+    pub(super) fn update(&mut self, f: &AlignedFile) -> Result<()> {
         let headers = VhdxHeader::update_headers(f, Ok(self.header_1), Ok(self.header_2), 0)?;
         self.header_1 = headers.0;
         self.header_2 = headers.1;
         Ok(())
     }
 
-    pub fn region_entry_count(&self) -> u32 {
+    pub(super) fn region_entry_count(&self) -> u32 {
         self.region_table_1.entry_count
     }
 }

block/src/formats/vhdx/io.rs

@@ -33,7 +33,7 @@ pub enum VhdxIoError {
     WriteBat(#[source] VhdxBatError),
 }
 
-pub type Result<T> = result::Result<T, VhdxIoError>;
+pub(super) type Result<T> = result::Result<T, VhdxIoError>;
 
 macro_rules! align {
     ($n:expr, $align:expr) => {{ $n.div_ceil($align) * $align }};
@@ -51,7 +51,7 @@ struct Sector {
 impl Sector {
     /// Translate sector index and count of data in file to actual offsets and
     /// BAT index.
-    pub fn new(
+    pub(crate) fn new(
         disk_spec: &DiskSpec,
         bat: &[BatEntry],
         sector_index: u64,
@@ -86,7 +86,7 @@ impl Sector {
 
 /// VHDx IO read routine: requires relative sector index and count for the
 /// requested data.
-pub fn read(
+pub(super) fn read(
     f: &AlignedFile,
     buf: &mut [u8],
     disk_spec: &DiskSpec,
@@ -138,7 +138,7 @@ pub fn read(
 
 /// VHDx IO write routine: requires relative sector index and count for the
 /// requested data.
-pub fn write(
+pub(super) fn write(
     f: &AlignedFile,
     buf: &[u8],
     disk_spec: &mut DiskSpec,

block/src/formats/vhdx/metadata.rs

@@ -21,7 +21,7 @@ const METADATA_TABLE_MAX_SIZE: usize = METADATA_ENTRY_SIZE * (METADATA_MAX_ENTRI
 
 const METADATA_FLAGS_IS_REQUIRED: u32 = 0x04;
 
-pub const BLOCK_SIZE_MIN: u32 = 1 << 20; // 1 MiB
+pub(super) const BLOCK_SIZE_MIN: u32 = 1 << 20; // 1 MiB
 const BLOCK_SIZE_MAX: u32 = 256 << 20; // 256 MiB
 const MAX_SECTORS_PER_BLOCK: u64 = 1 << 23;
 
@@ -93,10 +93,10 @@ pub enum VhdxMetadataError {
     UnsupportedFlag,
 }
 
-pub type Result<T> = result::Result<T, VhdxMetadataError>;
+pub(super) type Result<T> = result::Result<T, VhdxMetadataError>;
 
 #[derive(Default, Clone, Debug)]
-pub struct DiskSpec {
+pub(super) struct DiskSpec {
     pub disk_id: u128,
     pub image_size: u64,
     pub block_size: u32,
@@ -112,7 +112,7 @@ pub struct DiskSpec {
 impl DiskSpec {
     /// Parse all metadata from the provided file and store info in DiskSpec
     /// structure.
-    pub fn new(f: &AlignedFile, metadata_region: &RegionTableEntry) -> Result<DiskSpec> {
+    pub(super) fn new(f: &AlignedFile, metadata_region: &RegionTableEntry) -> Result<DiskSpec> {
         let mut disk_spec = DiskSpec::default();
         let mut metadata_presence: u16 = 0;
         let mut offset = 0;
@@ -270,7 +270,7 @@ struct MetadataTableHeader {
 }
 
 impl MetadataTableHeader {
-    pub fn new(buffer: &[u8]) -> Result<MetadataTableHeader> {
+    pub(crate) fn new(buffer: &[u8]) -> Result<MetadataTableHeader> {
         let metadata_table_header = MetadataTableHeader::read_from_bytes(buffer).unwrap();
 
         if metadata_table_header.signature != METADATA_SIGN {
@@ -291,7 +291,7 @@ impl MetadataTableHeader {
 
 #[repr(C, packed)]
 #[derive(Default, Debug, Clone, Copy, FromBytes)]
-pub struct MetadataTableEntry {
+pub(super) struct MetadataTableEntry {
     item_id: [u8; 16],
     offset: u32,
     length: u32,

block/src/formats/vhdx/mod.rs

@@ -9,19 +9,23 @@
 //! Provides [`VhdxDisk`], the `DiskFile` wrapper for dynamic VHDX
 //! images.
 
-pub mod internal;
+mod bat;
+mod engine_sync;
+mod header;
+mod io;
+mod metadata;
+mod parser;
 #[cfg(test)]
-pub(crate) mod test_util;
+mod test_util;
-pub(crate) mod worker;
 
 use std::fs::File;
-use std::io;
+use std::io::Error as IoError;
 use std::os::fd::AsRawFd;
 use std::sync::{Arc, Mutex};
 
-pub use internal::{Vhdx, VhdxError};
+pub use parser::{Vhdx, VhdxError};
 
-use self::worker::sync::VhdxSync;
+use self::engine_sync::VhdxSync;
 use crate::async_io::{AsyncIo, BorrowedDiskFd, DiskFileError};
 use crate::error::{BlockError, BlockErrorKind, BlockResult, ErrorOp};
 use crate::{Error, disk_file};
@@ -92,7 +96,7 @@ impl disk_file::Resizable for VhdxDisk {
     fn resize(&mut self, _size: u64) -> BlockResult<()> {
         Err(BlockError::new(
             BlockErrorKind::UnsupportedFeature,
-            DiskFileError::ResizeError(io::Error::other("resize not supported for VHDX")),
+            DiskFileError::ResizeError(IoError::other("resize not supported for VHDX")),
         )
         .with_op(ErrorOp::Resize))
     }

block/src/formats/vhdx/parser.rs

@@ -13,17 +13,12 @@ use std::result;
 use remain::sorted;
 use thiserror::Error;
 
-use self::bat::{BatEntry, VhdxBatError};
+use super::bat::{BatEntry, VhdxBatError};
-use self::header::{RegionInfo, RegionTableEntry, VhdxHeader, VhdxHeaderError};
+use super::header::{self, RegionInfo, RegionTableEntry, VhdxHeader, VhdxHeaderError};
-use self::io::VhdxIoError;
+use super::io::{self, VhdxIoError};
-use self::metadata::{DiskSpec, VhdxMetadataError};
+use super::metadata::{DiskSpec, VhdxMetadataError};
 use crate::aligned_file::AlignedFile;
 
-mod bat;
-mod header;
-mod io;
-mod metadata;
-
 #[sorted]
 #[derive(Error, Debug)]
 pub enum VhdxError {
@@ -43,7 +38,7 @@ pub enum VhdxError {
     WriteFailed(#[source] VhdxIoError),
 }
 
-pub type Result<T> = result::Result<T, VhdxError>;
+pub(super) type Result<T> = result::Result<T, VhdxError>;
 
 #[derive(Debug)]
 pub struct Vhdx {

block/src/formats/vhdx/worker/mod.rs

@@ -1,7 +0,0 @@
-// Copyright 2026 The Cloud Hypervisor Authors. All rights reserved.
-//
-// SPDX-License-Identifier: Apache-2.0
-
-//! Sync I/O worker for VHDX images.
-
-pub(crate) mod sync;