Sergio Lopez c5a656c9dc vm-virtio: block: Add support for alignment restrictions ...

Doing I/O on an image opened with O_DIRECT requires to adhere to
certain restrictions, requiring the following elements to be aligned:

 - Address of the source/destination memory buffer.
 - File offset.
 - Length of the data to be read/written.

The actual alignment value depends on various elements, and according
to open(2) "(...) there is currently no filesystem-independent
interface for an application to discover these restrictions (...)".

To discover such value, we iterate through a list of alignments
(currently, 512 and 4096) calling pread() with each one and checking
if the operation succeeded.

We also extend RawFile so it can be used as a backend for QcowFile,
so the later can be easily adapted to support O_DIRECT too.

Signed-off-by: Sergio Lopez <slp@redhat.com>

2020-01-17 17:28:44 +00:00

..

src

vm-virtio: block: Add support for alignment restrictions

2020-01-17 17:28:44 +00:00

Cargo.toml

vm-virtio, vmm, vfio: Store GuestMemoryMmap in an Arc<ArcSwap<T>>

2020-01-02 13:20:11 +00:00