ad82d45928
Co-developed-by: Erik Schilling <erik.schilling@linaro.org> Signed-off-by: Erik Schilling <erik.schilling@linaro.org> Signed-off-by: Gaelan Steele <gbs@canishe.com>
1.7 KiB
vhost-user-scsi architecture
Rough outline of the different pieces and how they fit together:
scsi/mod.rs
This defines the Target trait, which represents a SCSI target. The code in
this file is independent from:
- A particular SCSI implementation: Currently, we have one implementation of
Target, which emulates the SCSI commands itself; but future implementations could provide pass-through to an iSCSI target or SCSI devices attached to the host. - A particular SCSI transport: Nothing in
src/scsi/*knows anything about virtio; this is helpful for maintainability, and also allows our SCSI emulation code to be reusable as, for example, an iSCSI target. To this end, theTargettrait is generic over aReadandWritethat it uses for SCSI data transfer. This makes testing easy: we can just provide aVec<u8>to write into.
scsi/emulation/*.rs
This is the SCSI emulation code, which forms the bulk of the crate. It provides
EmulatedTarget, an implementation of Target. EmulatedTarget, in turn,
looks at the LUN and delegates commands to an implementation of LogicalUnit.
In most cases, this will be BlockDevice; there's also MissingLun, which is
used for responding to commands to invalid LUNs.
Currently, there is no separation between commands defined in the SPC standard (commands shared by all device types) and the SBC standard (block-device specific commands). If we ever implemented another device type (CD/DVD seems most likely), we'd want to separate those out.
As noted above, the emulation code knows nothing about virtio.
src/{main,virtio}.rs
This code handles vhost-user, virtio, and virtio-scsi; it's the only part of the crate that knows about these protocols.