-/**
- * Transfer request operations definable at every layer.
- *
- * Concurrency: transfer formation engine synchronizes calls to all transfer
- * methods.
- */
-struct cl_req_operations {
- /**
- * Invoked top-to-bottom by cl_req_prep() when transfer formation is
- * complete (all pages are added).
- *
- * \see osc_req_prep()
- */
- int (*cro_prep)(const struct lu_env *env,
- const struct cl_req_slice *slice);
- /**
- * Called top-to-bottom to fill in \a oa fields. This is called twice
- * with different flags, see bug 10150 and osc_build_req().
- *
- * \param obj an object from cl_req which attributes are to be set in
- * \a oa.
- *
- * \param oa struct obdo where attributes are placed
- *
- * \param flags \a oa fields to be filled.
- */
- void (*cro_attr_set)(const struct lu_env *env,
- const struct cl_req_slice *slice,
- const struct cl_object *obj,
- struct cl_req_attr *attr, u64 flags);
- /**
- * Called top-to-bottom from cl_req_completion() to notify layers that
- * transfer completed. Has to free all state allocated by
- * cl_device_operations::cdo_req_init().
- */
- void (*cro_completion)(const struct lu_env *env,
- const struct cl_req_slice *slice, int ioret);
-};
-
-/**
- * A per-object state that (potentially multi-object) transfer request keeps.
- */
-struct cl_req_obj {
- /** object itself */
- struct cl_object *ro_obj;
- /** reference to cl_req_obj::ro_obj. For debugging. */
- struct lu_ref_link ro_obj_ref;
- /* something else? Number of pages for a given object? */
-};
-
-/**
- * Transfer request.
- *
- * Transfer requests are not reference counted, because IO sub-system owns
- * them exclusively and knows when to free them.
- *
- * Life cycle.
- *
- * cl_req is created by cl_req_alloc() that calls
- * cl_device_operations::cdo_req_init() device methods to allocate per-req
- * state in every layer.
- *
- * Then pages are added (cl_req_page_add()), req keeps track of all objects it
- * contains pages for.
- *
- * Once all pages were collected, cl_page_operations::cpo_prep() method is
- * called top-to-bottom. At that point layers can modify req, let it pass, or
- * deny it completely. This is to support things like SNS that have transfer
- * ordering requirements invisible to the individual req-formation engine.
- *
- * On transfer completion (or transfer timeout, or failure to initiate the
- * transfer of an allocated req), cl_req_operations::cro_completion() method
- * is called, after execution of cl_page_operations::cpo_completion() of all
- * req's pages.
- */
-struct cl_req {
- enum cl_req_type crq_type;
- /** A list of pages being transfered */
- struct list_head crq_pages;
- /** Number of pages in cl_req::crq_pages */
- unsigned crq_nrpages;
- /** An array of objects which pages are in ->crq_pages */
- struct cl_req_obj *crq_o;
- /** Number of elements in cl_req::crq_objs[] */
- unsigned crq_nrobjs;
- struct list_head crq_layers;
-};
-
-/**
- * Per-layer state for request.
- */
-struct cl_req_slice {
- struct cl_req *crs_req;
- struct cl_device *crs_dev;
- struct list_head crs_linkage;
- const struct cl_req_operations *crs_ops;
-};
-
-/* @} cl_req */
-