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6305c66f22
There was some reference left in the documentation and sources to "vhost-user-scsi" that we had changed during the rebase. Let's change them to "vhost-device-scsi". Everything should be safe. We leave "vhost-user-scsi" in crates/scsi/src/scsi/emulation/response_data.rs because it looks like an identifier with some constant size. We will fix in the future. Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
40 lines
1.7 KiB
Markdown
40 lines
1.7 KiB
Markdown
# vhost-device-scsi architecture
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Rough outline of the different pieces and how they fit together:
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## `scsi/mod.rs`
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This defines the `Target` trait, which represents a SCSI target. The code in
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this file is independent from:
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- A particular SCSI implementation: Currently, we have one implementation of
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`Target`, which emulates the SCSI commands itself; but future implementations
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could provide pass-through to an iSCSI target or SCSI devices attached to the
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host.
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- A particular SCSI transport: Nothing in `src/scsi/*` knows anything about
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virtio; this is helpful for maintainability, and also allows our SCSI
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emulation code to be reusable as, for example, an iSCSI target. To this end,
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the `Target` trait is generic over a `Read` and `Write` that it uses for SCSI
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data transfer. This makes testing easy: we can just provide a `Vec<u8>` to
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write into.
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## `scsi/emulation/*.rs`
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This is the SCSI emulation code, which forms the bulk of the crate. It provides
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`EmulatedTarget`, an implementation of `Target`. `EmulatedTarget`, in turn,
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looks at the LUN and delegates commands to an implementation of `LogicalUnit`.
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In most cases, this will be `BlockDevice`; there's also `MissingLun`, which is
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used for responding to commands to invalid LUNs.
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Currently, there is no separation between commands defined in the SPC standard
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(commands shared by all device types) and the SBC standard (block-device
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specific commands). If we ever implemented another device type (CD/DVD seems
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most likely), we'd want to separate those out.
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As noted above, the emulation code knows nothing about virtio.
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## `src/{main,virtio}.rs`
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This code handles vhost-user, virtio, and virtio-scsi; it's the only part of
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the crate that knows about these protocols.
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