This patch introduce device data structure in Rust.
It can later support chunk based block maps.

Signed-off-by: Yiyang Wu <toolmanp@tlmp.cc>
---
 fs/erofs/rust/erofs_sys.rs         |  1 +
 fs/erofs/rust/erofs_sys/devices.rs | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)
 create mode 100644 fs/erofs/rust/erofs_sys/devices.rs

diff --git a/fs/erofs/rust/erofs_sys.rs b/fs/erofs/rust/erofs_sys.rs
index 8cca2cd9b75f..f1a1e491caec 100644
--- a/fs/erofs/rust/erofs_sys.rs
+++ b/fs/erofs/rust/erofs_sys.rs
@@ -25,6 +25,7 @@
 
 pub(crate) mod alloc_helper;
 pub(crate) mod data;
+pub(crate) mod devices;
 pub(crate) mod errnos;
 pub(crate) mod inode;
 pub(crate) mod superblock;
diff --git a/fs/erofs/rust/erofs_sys/devices.rs b/fs/erofs/rust/erofs_sys/devices.rs
new file mode 100644
index 000000000000..097676ee8720
--- /dev/null
+++ b/fs/erofs/rust/erofs_sys/devices.rs
@@ -0,0 +1,28 @@
+// Copyright 2024 Yiyang Wu
+// SPDX-License-Identifier: MIT or GPL-2.0-or-later
+
+use alloc::vec::Vec;
+
+/// Device specification.
+#[derive(Copy, Clone, Debug)]
+pub(crate) struct DeviceSpec {
+    pub(crate) tags: [u8; 64],
+    pub(crate) blocks: u32,
+    pub(crate) mapped_blocks: u32,
+}
+
+/// Device slot.
+#[derive(Copy, Clone, Debug)]
+#[repr(C)]
+pub(crate) struct DeviceSlot {
+    tags: [u8; 64],
+    blocks: u32,
+    mapped_blocks: u32,
+    reserved: [u8; 56],
+}
+
+/// Device information.
+pub(crate) struct DeviceInfo {
+    pub(crate) mask: u16,
+    pub(crate) specs: Vec<DeviceSpec>,
+}
-- 
2.46.0