- /**
- * \name statemachine
- *
- * State machine transitions. These 3 methods are called to transfer
- * lock from one state to another, as described in the commentary
- * above enum #cl_lock_state.
- *
- * \retval 0 this layer has nothing more to do to before
- * transition to the target state happens;
- *
- * \retval CLO_REPEAT method had to release and re-acquire cl_lock
- * mutex, repeat invocation of transition method
- * across all layers;
- *
- * \retval CLO_WAIT this layer cannot move to the target state
- * immediately, as it has to wait for certain event
- * (e.g., the communication with the server). It
- * is guaranteed, that when the state transfer
- * becomes possible, cl_lock::cll_wq wait-queue
- * is signaled. Caller can wait for this event by
- * calling cl_lock_state_wait();
- *
- * \retval -ve failure, abort state transition, move the lock
- * into cl_lock_state::CLS_FREEING state, and set
- * cl_lock::cll_error.
- *
- * Once all layers voted to agree to transition (by returning 0), lock
- * is moved into corresponding target state. All state transition
- * methods are optional.
- */
- /** @{ */
- /**
- * Attempts to enqueue the lock. Called top-to-bottom.
- *
- * \see ccc_lock_enqueue(), lov_lock_enqueue(), lovsub_lock_enqueue(),
- * \see osc_lock_enqueue()
- */
- int (*clo_enqueue)(const struct lu_env *env,
- const struct cl_lock_slice *slice,
- struct cl_io *io, __u32 enqflags);
- /**
- * Attempts to wait for enqueue result. Called top-to-bottom.
- *
- * \see ccc_lock_wait(), lov_lock_wait(), osc_lock_wait()
- */
- int (*clo_wait)(const struct lu_env *env,
- const struct cl_lock_slice *slice);
- /**
- * Attempts to unlock the lock. Called bottom-to-top. In addition to
- * usual return values of lock state-machine methods, this can return
- * -ESTALE to indicate that lock cannot be returned to the cache, and
- * has to be re-initialized.
- * unuse is a one-shot operation, so it must NOT return CLO_WAIT.
- *
- * \see ccc_lock_unuse(), lov_lock_unuse(), osc_lock_unuse()
- */
- int (*clo_unuse)(const struct lu_env *env,
- const struct cl_lock_slice *slice);
- /**
- * Notifies layer that cached lock is started being used.
- *
- * \pre lock->cll_state == CLS_CACHED
- *
- * \see lov_lock_use(), osc_lock_use()
- */
- int (*clo_use)(const struct lu_env *env,
- const struct cl_lock_slice *slice);
- /** @} statemachine */
- /**
- * A method invoked when lock state is changed (as a result of state
- * transition). This is used, for example, to track when the state of
- * a sub-lock changes, to propagate this change to the corresponding
- * top-lock. Optional
- *
- * \see lovsub_lock_state()
- */
- void (*clo_state)(const struct lu_env *env,
- const struct cl_lock_slice *slice,
- enum cl_lock_state st);
- /**
- * Returns true, iff given lock is suitable for the given io, idea
- * being, that there are certain "unsafe" locks, e.g., ones acquired
- * for O_APPEND writes, that we don't want to re-use for a normal
- * write, to avoid the danger of cascading evictions. Optional. Runs
- * under cl_object_header::coh_lock_guard.
- *
- * XXX this should take more information about lock needed by
- * io. Probably lock description or something similar.
- *
- * \see lov_fits_into()
- */
- int (*clo_fits_into)(const struct lu_env *env,
- const struct cl_lock_slice *slice,
- const struct cl_lock_descr *need,
- const struct cl_io *io);
- /**
- * \name ast
- * Asynchronous System Traps. All of then are optional, all are
- * executed bottom-to-top.
- */
- /** @{ */
-
- /**
- * Cancellation callback. Cancel a lock voluntarily, or under
- * the request of server.
- */
- void (*clo_cancel)(const struct lu_env *env,
- const struct cl_lock_slice *slice);
- /**
- * Lock weighting ast. Executed to estimate how precious this lock
- * is. The sum of results across all layers is used to determine
- * whether lock worth keeping in cache given present memory usage.
- *
- * \see osc_lock_weigh(), vvp_lock_weigh(), lovsub_lock_weigh().
- */
- unsigned long (*clo_weigh)(const struct lu_env *env,
- const struct cl_lock_slice *slice);
- /** @} ast */
-
- /**
- * \see lovsub_lock_closure()
- */
- int (*clo_closure)(const struct lu_env *env,
- const struct cl_lock_slice *slice,
- struct cl_lock_closure *closure);
- /**
- * Executed bottom-to-top when lock description changes (e.g., as a
- * result of server granting more generous lock than was requested).
- *
- * \see lovsub_lock_modify()
- */
- int (*clo_modify)(const struct lu_env *env,
- const struct cl_lock_slice *slice,
- const struct cl_lock_descr *updated);
- /**
- * Notifies layers (bottom-to-top) that lock is going to be
- * destroyed. Responsibility of layers is to prevent new references on
- * this lock from being acquired once this method returns.
- *
- * This can be called multiple times due to the races.
- *
- * \see cl_lock_delete()
- * \see osc_lock_delete(), lovsub_lock_delete()
- */
- void (*clo_delete)(const struct lu_env *env,
- const struct cl_lock_slice *slice);