Gleb Chesnokov
38823eb5e2
SCST spans a kernel core, transport drivers, user-space programs and configuration tools. Each area has different ABI, build, validation and safety constraints, but the repository has no persistent guidance for automated contributors. Add a root AGENTS.md with cross-component contracts and nested files for components with independent boundaries. Record authoritative sources, generated files, compatibility policy and destructive workflows so changes start from the correct context and avoid live storage state.
2.2 KiB
SCST Local Target
Ownership and interfaces
This directory owns the scst_local loopback target: it presents SCST-exported
LUNs back to the same kernel through the SCSI midlayer. scst_local.c owns the
SCST target template, local SCSI host/command bridge, target/session management,
TransportID attributes, error handling, and teardown. Kbuild, Makefile, and
in-tree/ own out-of-tree and in-tree composition.
Start with scst/include/scst.h for the common target-driver contract and
scst/SysfsRules for common configuration conventions, then verify both in
their current implementations. README documents the local sysfs additions
and the user-space-target use case, but exact locking and lifecycle behavior
must be read from current code.
Change boundaries
- One command crosses both the local SCSI initiator lifecycle and the SCST target lifecycle. Preserve completion-once, abort/reset, queueing, sense/data, session, device-release, and target-unregister ownership across both sides.
- Session/adapter removal interacts with SCST and device-model locks. Re-derive the current lock order and deferred-release requirements before changing close or teardown paths; do not call device removal while holding a lock that the callback path can reacquire.
- Sysfs management commands and target/session attributes are consumed by
scstadmin. Audit parser/serializer/discovery behavior for changes. A shared SCST callback change still requires all target drivers to be checked.
Generated files, validation, and safety
Objects, modules, Module.symvers, and dependency metadata are generated.
The focused compile entry point is top-level make scst_local or this
component's Makefile; no component unit-test target exists.
This driver can expose storage recursively on the same host. Never load it,
create local targets/sessions/LUNs, mount or use returned devices, or run abort/
reset/teardown tests without explicit authorization. In particular, preserve
the backing-mode restrictions implemented by the current I/O and allocation
paths; use README to locate the risk, not as a substitute for checking the
code. Unsafe local use can recurse into memory reclaim and deadlock or corrupt
the backing storage.