The `read_aligned_block_size()` function used `Vec::from_raw_parts()`
incorrectly, causing undefined behavior when deallocating the `Vec<u8>`.
One of the safety invariants of `Vec::from_raw_parts()` is that the
provided pointer must be allocated with the exact same alignment as `T`
(`u8` in this case), but this is clearly not true: `align_of::<u8>()` is
1, but the pointer was allocated with aligment of `blocksize` (typically
512 or greater).
Fix this by using the existing `AlignedFile` helper to read the header
block when probing the image type. This is slightly less efficient than
using `AlignedBuffer` directly, but since this is only called once per
disk image at startup, the difference is probably not worth the extra
verbosity.
Signed-off-by: Daniel Verkamp <drv@meta.com>
BlockBackend predated the disk_file trait family and only carried
logical_size and physical_size, which the disk backends expose
through the disk_file traits DiskSize and PhysicalSize.
It added no polymorphism while its Read, Write and Seek supertraits
forced an unused cursor. Dropping the trait removes the dead code
it was keeping alive.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
RawFile wrapped AlignedFile only to add a seek position and the file
trait impls that the qcow and vhost_user_block code expects. Fold that
position and every impl onto AlignedFile so the wrapper layer goes away
and callers work with a single O_DIRECT aware file type.
AlignedFile now tracks a cursor and implements Read, Write, Seek,
WriteZeroesAt, PunchHole, FileSync, SeekHole, BlockBackend, Clone,
AsRawFd and AsFd in addition to the positional FileExt path. The
direct_io flag is dropped because alignment already encodes it, where
a zero alignment means the file was not opened with O_DIRECT.
All RawFile uses in the qcow internals and vhost_user_block move to
AlignedFile, and raw_file.rs is removed.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Move the statx STATX_DIOALIGN probe out of DiskTopology into a free
probe_direct_alignment helper keyed on a raw fd. The helper gates on the
O_DIRECT open flag and returns the kernel reported alignment only when
direct I/O is in effect, and None otherwise. DiskTopology::probe keeps
the same call path and result.
AlignedFile::new now determines its O_DIRECT block alignment from
probe_direct_alignment instead of trial reads at 512 and 4096, falling
back to SECTOR_SIZE when the kernel does not report a value. This
matches how the raw and fixed VHD workers determine alignment, so all
backends agree on one source of truth.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Provide a single home for O_DIRECT alignment and RMW behavior behind an
std::os::unix::fs::FileExt implementation built on AlignedBuffer.
Unaligned requests are bounced through an AlignedBuffer (applying RMW
for writes) and aligned requests pass straight through to the inner
File.
Assisted-by: Claude:Opus-4.8
Signed-off-by: Rob Bradford <rbradford@meta.com>
The block code repeatedly open-codes O_DIRECT alignment calculations and
bounce-buffer allocation at each I/O site. Add an AlignedBuffer struct
that handles the alignment and allocation in one place, using FileExt
(read_exact_at and write_all_at) for the I/O (so no need for custom libc
wrappers).
The caller creates an AlignedBuffer with an offset, length and
alignment, then uses read_from and write_to for aligned I/O and as_slice
and as_mut_slice to access the logical data portion within the aligned
region.
This is a lot like the AlignedBuf that was already existing in the QCOW2
code but is a more generalised version.
Assisted-by: Claude:Opus-4.6
Signed-off-by: Rob Bradford <rbradford@meta.com>
Import the std modules used in the crate instead of spelling the full
paths at every use site.
Signed-off-by: Henry Hrvoje Tonkovac <htonkovac@gmail.com>
Assisted-by: Claude:Opus-4.8
Re-export Vhdx from formats::vhdx and update the fuzz target to
use block::formats::vhdx::Vhdx. Remove the vhdx compat alias
from lib.rs.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Update external consumers to use formats::qcow::internal instead
of the top level qcow alias. Keep a crate private use for the
QcowError variant in lib.rs.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Update external consumers and internal test modules to use
formats::raw instead of the raw_disk alias, then remove the
re-export from lib.rs.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Move QCOW2 format implementation into a structured directory layout:
qcow/ -> formats/qcow/internal/ (filenames unchanged)
qcow_disk.rs -> formats/qcow/mod.rs (QcowDisk)
qcow_sync.rs -> formats/qcow/worker/sync.rs (QcowSync)
qcow_async.rs -> formats/qcow/worker/async_uring.rs (QcowAsync)
qcow_common.rs -> formats/qcow/common.rs
All internal cross references continue to resolve through
re-exports in lib.rs: formats::qcow::internal as qcow,
formats::qcow as qcow_disk, and
formats::qcow::common as qcow_common.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Move VHDX format implementation into a structured directory layout:
vhdx/mod.rs -> formats/vhdx/internal/mod.rs (Vhdx)
vhdx/vhdx_bat.rs -> formats/vhdx/internal/bat.rs
vhdx/vhdx_header.rs -> formats/vhdx/internal/header.rs
vhdx/vhdx_io.rs -> formats/vhdx/internal/io.rs
vhdx/vhdx_metadata.rs -> formats/vhdx/internal/metadata.rs
vhdx_sync.rs -> formats/vhdx/mod.rs (VhdxDisk)
Extract VhdxSync from vhdx_sync.rs into formats/vhdx/worker/sync.rs.
Drop the vhdx_ prefix from internal file names since the parent
directory already provides the namespace. Update all internal cross
references to use the new module paths. Re-export formats::vhdx as
vhdx_sync in lib.rs for backward compatibility.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Move VHD format implementation into a structured directory layout:
fixed_vhd.rs -> formats/vhd/internal/fixed.rs (FixedVhd)
fixed_vhd_disk.rs -> formats/vhd/mod.rs (VhdDisk)
vhd.rs -> formats/vhd/internal/footer.rs (VhdFooter)
fixed_vhd_sync.rs -> formats/vhd/worker/sync.rs (FixedVhdSync)
fixed_vhd_async.rs -> formats/vhd/worker/async_uring.rs (FixedVhdAsync)
Add #[allow(dead_code)] to VhdFooter struct and impl because the
module is now pub(crate) and the compiler can see that several
fields and getters are only exercised by unit tests. Re-export
formats::vhd as fixed_vhd_disk in lib.rs for backward
compatibility with external consumers.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Move raw format implementation into a structured directory layout:
raw_disk.rs -> formats/raw/mod.rs (RawDisk)
raw_sync.rs -> formats/raw/worker/sync.rs (RawSync)
raw_async.rs -> formats/raw/worker/async_uring.rs (RawAsync)
raw_async_aio.rs -> formats/raw/worker/async_aio.rs (RawAio)
raw_async_io_tests.rs -> formats/raw/worker/tests.rs
Update imports in fixed_vhd_sync.rs and fixed_vhd_async.rs to use
the new paths. Re-export formats::raw as raw_disk in lib.rs to
preserve the external API.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Move async_io.rs, fcntl.rs, and request.rs into block/src/io/. These
files are generic I/O infrastructure shared by all formats rather
than format specific code.
The io/ directory name clashes with std::io in lib.rs, so the module
is declared as io_impl via #[path] and the submodules are re-exported
at the crate root to keep existing import paths working.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Drop the borrowed iovec AsyncIo entry points now that all callers use
owned operations. Rename the transitional owned batch and completion
methods to the final trait names and remove the borrowed submission
helpers from the queue wrappers.
This removes a bunch of known safety foot-guns so future-us don't
accidentally use them.
Assisted-by: Codex:GPT-5.5
Signed-off-by: Dylan Reid <dgreid@fb.com>
Some block devices (ZFS volume) may require BLKDISCARD and BLKZEROOUT
ioctls for discard and write_zeroes operations respectively.
There is no good way to probe whether fallocate is supported on a block
device. Arguably, punch_hole and write_zeroes are rare. Instead of
having a complex scheme for the IO uring backend, we force it to always
use ioctls. The code can be changed if the synchronized ioctls become a
performance issue.
Changes:
- Detect block devices at construction time
- Use BLKDISCARD ioctl for punch_hole (discard) on block devices
- Use BLKZEROOUT ioctl for write_zeroes on block devices
- Add BLKDISCARD/BLKZEROOUT to VirtioBlock seccomp whitelist
- Keep fallocate() path for regular files (no behavior change)
- Consolidate some helper functions to the new sparse module
Signed-off-by: Wei Liu <liuwe@microsoft.com>
probe_sparse_support() and DiskTopology::is_block_device() each carry
their own copy of the same fstat()+S_IFMT dance to ask "is this fd a
block device?". Hoist a single pub helper
pub(crate) fn is_block_device(fd: RawFd) -> bool
into block::lib and route both call sites through it. Drop the
MaybeUninit gymnastics in favour of mem::zeroed() since libc::stat is
POD.
Drop DiskTopology::is_block_device since it is now just a one line
wrapper around the new helper function.
Pure refactor in preparation for the BLKDISCARD/BLKZEROOUT support,
which needs the same probe in three more backends.
Signed-off-by: Wei Liu <liuwe@microsoft.com>
The bounce buffer for an unaligned descriptor was allocated in
execute_async and leaked on error paths, even though, for the sync case
the kernel already had a pointer to the buffer.
Clean this up by moving ownership of the buffer to the AlignedOperation
type. To make it actually safe, stop stashing a guest memory pointer for
the duration of the op. Instead, save the guest address and pass guest
memory back to the complete function.
Signed-off-by: Dylan Reid <dgreid@fb.com>
Delete QcowDiskSync and QcowDiskAsync wrapper structs along with
their DiskFile trait impls. Only the AsyncIo worker structs
QcowSync and QcowAsync remain. Reduce module visibility of
qcow_sync and qcow_async to pub(crate).
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Introduce QcowDisk, a unified DiskFile implementation for QCOW2
disk images that handles backend selection at runtime via a
use_io_uring flag, matching the pattern used by FixedVhdDisk.
The wrapper delegates to QcowSync or QcowAsync based on the flag
and includes a compile time guard that returns an error when
io_uring is requested but the feature is not enabled.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Introduce FixedVhdDisk as a single DiskFile wrapper around FixedVhd.
It accepts a use_io_uring flag at construction time and dispatches to
FixedVhdSync or FixedVhdAsync inside create_async_io() accordingly.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Update open_raw to construct RawDisk instead of choosing between
RawFileDisk, RawFileDiskSync and RawFileDiskAio. The backend decision
is now made inside RawDisk::create_async_io.
Remove the DiskFile wrapper structs from raw_sync.rs, raw_async.rs
and raw_async_aio.rs. Only the AsyncIo worker structs remain in those
files. Reduce their module visibility to pub(crate).
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Introduce the unified DiskFile wrapper for raw disk images. The
RawBackend enum selects between sync, io_uring, and AIO backends
at construction time.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Introduce block::factory with open_disk() as the single entry point
for opening disk images. It handles file opening, format detection,
async I/O probing, and backend construction.
Per format helpers (open_fixed_vhd, open_raw, open_qcow2, open_vhdx)
prefer io_uring over AIO over synchronous fallback. Warnings only
fire when a backend was eligible but its runtime probe failed, not
when the user intentionally disabled it.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
There is no reason for most of the Request struct to be writable from
anywhere in the codebase. Encapsulate it.
Use getter functions for access outside the request module. Replace the
trivial setter for the writeback field with direct assignment.
No functional change intended.
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
The address that is passed from the guest should be treated as
untrusted. Currently an invalid address will panic the VMM. This only
allows the guest to hurt itself, but we shouldn't have the VMM crashing.
Instead let's return an error if possible or invalidate the queue if it
happen during setup.
The data flow from guest to translate_gva/translate_gpa is:
1. Guest writes a raw u64 address into a virtio descriptor in the
shared descriptor table (guest memory).
2. The virtio-queue crate reads this descriptor via read_obj() and
returns the addr field as-is in a GuestAddress — no validation.
3. Device code calls .translate_gva(access_platform, len) on the
GuestAddress.
4. With IOMMU (access_platform is Some): the address is an IOVA that
must be translated to a GPA via the IOMMU mapping table. If the
guest provides an unmapped IOVA, translation returns Err.
Previously, .unwrap() here panicked the VMM.
5. Without IOMMU (access_platform is None): translate_gva is a no-op
(returns self). The raw address flows to GuestMemory::read_obj()
which validates it — out-of-range addresses return
Err(InvalidGuestAddress), so no host memory corruption is possible.
Signed-off-by: Dylan Reid <dgreid@fb.com>
Per queue I/O worker that uses io_uring for asynchronous reads
against fully allocated clusters. The struct holds the shared
metadata, data file, optional backing reader, the io_uring
instance and a synthetic completion list.
Feature gated on io_uring in lib.rs.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Introduce the device level handle for the async QCOW2 backend.
QcowDiskAsync mirrors QcowDiskSync. It parses the image, resolves
the backing chain and wraps QcowMetadata in an Arc for sharing
across virtio queues. No trait impls yet, just the struct,
constructor, Drop and Debug.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
These position independent I/O helpers use pread64/pwrite64 to avoid
races on the shared file position when multiple queues operate on
duplicated file descriptors. Extracting them prepares for reuse by
the upcoming qcow_async backend.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Introduce ExecuteError::UnsupportedFlags to carry both the
request type and the rejected flags value, replacing the
generic ExecuteError::Unsupported at discard and write zeroes
flag validation sites. This provides structured context for
debugging without changing the returned VIRTIO_BLK_S_UNSUPP
status.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
The virtio spec v1.2 in 5.2.6.2 requires that the device
MUST return VIRTIO_BLK_S_UNSUPP for write zeroes commands
if any unknown flag is set.
Add an early check that rejects requests with reserved flag
bits set by returning VIRTIO_BLK_S_UNSUPP via the existing
ExecuteError::Unsupported variant.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
The virtio spec v1.2 in 5.2.6.2 requires that the device
MUST return VIRTIO_BLK_S_UNSUPP for discard commands if the
unmap flag is set or if any unknown flag is set.
The discard handler was not reading the flags field at all,
silently accepting requests with arbitrary flags. Read and
validate the flags, rejecting any non-zero value with
VIRTIO_BLK_S_UNSUPP.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Add a shared helper that returns the logical size in bytes for both
regular files and block devices using an immutable &File reference.
Regular files use metadata().len(). Block devices use the BLKGETSIZE64
ioctl. Any other file type returns an InvalidInput error.
This avoids seek(SeekFrom::End(0)) which requires &mut self and can
return incorrect results for block devices when the file position is
in an unexpected state.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Include the number of segments found in the request payload in
the TooManySegments error variant so the logged message shows
both the actual and maximum values.
Suggested-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Introduce DISCARD_WZ_MAX_PAYLOAD as the precomputed product of
DISCARD_WZ_SEG_SIZE and MAX_DISCARD_WRITE_ZEROES_SEG. Use it in the
DISCARD and WRITE_ZEROES segment count checks instead of repeating
the multiplication inline.
Suggested-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Add range validation for DISCARD and WRITE_ZEROES, matching the
existing check in the read/write path. Per virtio spec section
5.2.6.1, a driver must not submit a request which would cause a
read or write beyond capacity. Use checked_add to guard against
overflow, then compare against disk_nsectors.
Without this, requests beyond device capacity pass through to the
host punch_hole/write_zeroes calls, relying on backend specific
behavior rather than returning VIRTIO_BLK_S_IOERR consistently.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Split the data length check into two conditions:
- reject descriptors shorter than one
virtio_blk_discard_write_zeroes segment, and
- reject payloads exceeding MAX_DISCARD_WRITE_ZEROES_SEG segments
Previously only the minimum length was checked and extra segments
were silently dropped.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Composable disk capability traits with DiskFile as a supertrait
bundling DiskSize and Geometry. Optional capabilities are
separate traits: PhysicalSize, DiskFd, SparseCapable, Resizable.
AsyncDiskFile extends DiskFile with async I/O construction.
Empty module with doc comment, trait definitions follow.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Replace magic numeric offsets with mem::offset_of!() referencing the
virtio_blk_discard_write_zeroes struct from the virtio-bindings crate
when reading the sector, num_sectors and flags fields in the DISCARD
and WRITE_ZEROES request handlers.
No functional change.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
The write zeroes segment descriptor (struct
virtio_blk_discard_write_zeroes, virtio spec v1.2 section 5.2.6)
includes a flags field with an unmap bit. Per section 5.2.6.2, if
unmap is set, the device MAY deallocate the specified range of
sectors in the device backend storage, as if the discard command
had been sent.
Read the flags field and when the unmap bit is set, use punch_hole
to deallocate the range. Otherwise continue using write_zeroes via
ZERO_RANGE which preserves allocation.
This allows the guest to reclaim host disk space through write
zeroes requests on thin provisioned images.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
probe_file_sparse_support() defined FALLOC_FL_KEEP_SIZE,
FALLOC_FL_PUNCH_HOLE, and FALLOC_FL_ZERO_RANGE as local constants.
These are available from the libc crate directly.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Add raw_async_io_tests.rs with punch_hole, write_zeroes, and
multiple_operations helpers that take &mut dyn AsyncIo + &mut File.
These are raw-backend-specific. They verify data by reading the
underlying file directly, which only works for plain file backends
without container format metadata.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Add a small helper in the block crate that opens a disk image
file and wraps any failure in a BlockError carrying the file
path and operation context. Use it from the vmm device manager
so that a failed open now reports which path couldn't be opened.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Convert detect_image_type() from io::Result to BlockResult so
that I/O failures carry the operation name in the error context.
Update the corresponding vmm error variant to wrap BlockError.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Introduce error.rs as the home for a unified error hierarchy that
will replace the per format error types at the public crate
boundary. This commit is intentionally empty beyond the copyright
header and module declaration in lib.rs.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Test valid power of two alignment, layout compatibility,
direct helper coverage, and O_DIRECT write/read roundtrip.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
