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Host allocation size for file-backed disk images. Reports actual bytes occupied on the host filesystem. Not every format supports this, e.g. network or memory backed disks. Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
51 lines
1.8 KiB
Rust
51 lines
1.8 KiB
Rust
// Copyright 2026 The Cloud Hypervisor Authors. All rights reserved.
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//
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// SPDX-License-Identifier: Apache-2.0
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//! Composable disk capability traits for the block crate.
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//!
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//! Small traits define individual capabilities:
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//!
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//! - [`DiskSize`] - reported capacity (logical size)
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//! - [`PhysicalSize`] - host allocation size
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//! - [`DiskFd`] - backing file descriptor access
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//! - [`Geometry`] - sector/cluster geometry (default 512B)
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//! - [`SparseCapable`] - sparse and zero flag support
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//! - [`Resizable`] - online resize
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//!
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//! [`DiskFile`] is a supertrait that bundles the universal capabilities
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//! (`DiskSize` + `Geometry`). [`FullDiskFile`] adds all optional
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//! capabilities. [`AsyncDiskFile`] extends `DiskFile` with async I/O
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//! construction for virtio queue workers. [`AsyncFullDiskFile`]
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//! combines both axes.
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//!
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//! ```text
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//! DiskFile: DiskSize + Geometry + Sync
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//! / \
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//! FullDiskFile: AsyncDiskFile:
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//! DiskFile + PhysicalSize + DiskFile + Unpin
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//! DiskFd + SparseCapable + try_clone, new_async_io
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//! Resizable
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//! \ /
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//! AsyncFullDiskFile: FullDiskFile + AsyncDiskFile
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//! ```
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//!
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//! Readonly accessors take `&self`. Only [`Resizable::resize`] requires
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//! `&mut self`. Errors are returned as [`BlockResult`].
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use std::fmt::Debug;
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use crate::BlockResult;
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/// Reported capacity of a disk image.
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pub trait DiskSize: Send + Debug {
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/// Virtual size of the disk image in bytes (reported capacity).
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fn logical_size(&self) -> BlockResult<u64>;
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}
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/// Host allocation size of a file-backed disk image.
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pub trait PhysicalSize: Send + Debug {
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/// Actual bytes occupied on the host filesystem.
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fn physical_size(&self) -> BlockResult<u64>;
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}
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