Anatol Belski 3f20fd0759 block: qcow: Drop own O_DIRECT alignment handling ...

The qcow workers carried their own O_DIRECT alignment requirement
and bounced unaligned cluster accesses through AlignedBuffer. Now
that the data file is an AlignedFile that handles O_DIRECT
transparently, the qcow layer can read and write through plain
buffers and let AlignedFile perform the aligned bounce.

Remove the alignment field and the per cluster AlignedBuffer RMW
branches from both the sync and async workers. The async io_uring
fast path still needs to avoid submitting unaligned guest iovecs
under O_DIRECT, so gate it on is_direct rather than on a stored
alignment value.

Drop the QcowAsync alignment override so it reports the trait
default sector size, matching QcowSync. qcow never submits guest
iovecs to the kernel under O_DIRECT, so reporting a larger value
only forced the request layer into an extra bounce buffer.

This adds one buffer copy per unaligned O_DIRECT cluster but moves
all alignment handling into a single place. The buffered path is
unchanged.

With qcow no longer the only caller, AlignedBuffer::read_exact_from
becomes dead code, so remove it and switch its tests to read_from.

Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>

2026-06-20 11:46:17 +00:00

..

src

block: qcow: Drop own O_DIRECT alignment handling

2026-06-20 11:46:17 +00:00

Cargo.toml

performance-metrics: Switch to QcowDisk

2026-06-08 13:19:32 +00:00