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>
By redirecting VHDx I/O through the AlignedFile the required RMW
semantics can be achieved for writes less than the logical block size
whilt reusing the same logic used for other backend implementations.
Assisted-by: Claude:Opus-4.8
Signed-off-by: Rob Bradford <rbradford@meta.com>
Reuse the functionality in the AlignedFile wrapper for the QCOW RawFile
wrapper. This makes alignment handling more transparent.
Assisted-by: Claude:Opus-4.8
Signed-off-by: Rob Bradford <rbradford@meta.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>
