// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2023 Red Hat
 */

#include "admin-state.h"

#include "logger.h"
#include "memory-alloc.h"
#include "permassert.h"

#include "completion.h"
#include "types.h"

static const struct admin_state_code VDO_CODE_NORMAL_OPERATION = {
 .name = "VDO_ADMIN_STATE_NORMAL_OPERATION",
 .normal = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_NORMAL_OPERATION = &VDO_CODE_NORMAL_OPERATION;
static const struct admin_state_code VDO_CODE_OPERATING = {
 .name = "VDO_ADMIN_STATE_OPERATING",
 .normal = true,
 .operating = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_OPERATING = &VDO_CODE_OPERATING;
static const struct admin_state_code VDO_CODE_FORMATTING = {
 .name = "VDO_ADMIN_STATE_FORMATTING",
 .operating = true,
 .loading = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_FORMATTING = &VDO_CODE_FORMATTING;
static const struct admin_state_code VDO_CODE_PRE_LOADING = {
 .name = "VDO_ADMIN_STATE_PRE_LOADING",
 .operating = true,
 .loading = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_PRE_LOADING = &VDO_CODE_PRE_LOADING;
static const struct admin_state_code VDO_CODE_PRE_LOADED = {
 .name = "VDO_ADMIN_STATE_PRE_LOADED",
};
const struct admin_state_code *VDO_ADMIN_STATE_PRE_LOADED = &VDO_CODE_PRE_LOADED;
static const struct admin_state_code VDO_CODE_LOADING = {
 .name = "VDO_ADMIN_STATE_LOADING",
 .normal = true,
 .operating = true,
 .loading = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_LOADING = &VDO_CODE_LOADING;
static const struct admin_state_code VDO_CODE_LOADING_FOR_RECOVERY = {
 .name = "VDO_ADMIN_STATE_LOADING_FOR_RECOVERY",
 .operating = true,
 .loading = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_LOADING_FOR_RECOVERY =
 &VDO_CODE_LOADING_FOR_RECOVERY;
static const struct admin_state_code VDO_CODE_LOADING_FOR_REBUILD = {
 .name = "VDO_ADMIN_STATE_LOADING_FOR_REBUILD",
 .operating = true,
 .loading = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_LOADING_FOR_REBUILD = &VDO_CODE_LOADING_FOR_REBUILD;
static const struct admin_state_code VDO_CODE_WAITING_FOR_RECOVERY = {
 .name = "VDO_ADMIN_STATE_WAITING_FOR_RECOVERY",
 .operating = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_WAITING_FOR_RECOVERY =
 &VDO_CODE_WAITING_FOR_RECOVERY;
static const struct admin_state_code VDO_CODE_NEW = {
 .name = "VDO_ADMIN_STATE_NEW",
 .quiescent = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_NEW = &VDO_CODE_NEW;
static const struct admin_state_code VDO_CODE_INITIALIZED = {
 .name = "VDO_ADMIN_STATE_INITIALIZED",
};
const struct admin_state_code *VDO_ADMIN_STATE_INITIALIZED = &VDO_CODE_INITIALIZED;
static const struct admin_state_code VDO_CODE_RECOVERING = {
 .name = "VDO_ADMIN_STATE_RECOVERING",
 .draining = true,
 .operating = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_RECOVERING = &VDO_CODE_RECOVERING;
static const struct admin_state_code VDO_CODE_REBUILDING = {
 .name = "VDO_ADMIN_STATE_REBUILDING",
 .draining = true,
 .operating = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_REBUILDING = &VDO_CODE_REBUILDING;
static const struct admin_state_code VDO_CODE_SAVING = {
 .name = "VDO_ADMIN_STATE_SAVING",
 .draining = true,
 .quiescing = true,
 .operating = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_SAVING = &VDO_CODE_SAVING;
static const struct admin_state_code VDO_CODE_SAVED = {
 .name = "VDO_ADMIN_STATE_SAVED",
 .quiescent = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_SAVED = &VDO_CODE_SAVED;
static const struct admin_state_code VDO_CODE_SCRUBBING = {
 .name = "VDO_ADMIN_STATE_SCRUBBING",
 .draining = true,
 .loading = true,
 .operating = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_SCRUBBING = &VDO_CODE_SCRUBBING;
static const struct admin_state_code VDO_CODE_SAVE_FOR_SCRUBBING = {
 .name = "VDO_ADMIN_STATE_SAVE_FOR_SCRUBBING",
 .draining = true,
 .operating = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_SAVE_FOR_SCRUBBING = &VDO_CODE_SAVE_FOR_SCRUBBING;
static const struct admin_state_code VDO_CODE_STOPPING = {
 .name = "VDO_ADMIN_STATE_STOPPING",
 .draining = true,
 .quiescing = true,
 .operating = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_STOPPING = &VDO_CODE_STOPPING;
static const struct admin_state_code VDO_CODE_STOPPED = {
 .name = "VDO_ADMIN_STATE_STOPPED",
 .quiescent = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_STOPPED = &VDO_CODE_STOPPED;
static const struct admin_state_code VDO_CODE_SUSPENDING = {
 .name = "VDO_ADMIN_STATE_SUSPENDING",
 .draining = true,
 .quiescing = true,
 .operating = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_SUSPENDING = &VDO_CODE_SUSPENDING;
static const struct admin_state_code VDO_CODE_SUSPENDED = {
 .name = "VDO_ADMIN_STATE_SUSPENDED",
 .quiescent = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_SUSPENDED = &VDO_CODE_SUSPENDED;
static const struct admin_state_code VDO_CODE_SUSPENDED_OPERATION = {
 .name = "VDO_ADMIN_STATE_SUSPENDED_OPERATION",
 .operating = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_SUSPENDED_OPERATION = &VDO_CODE_SUSPENDED_OPERATION;
static const struct admin_state_code VDO_CODE_RESUMING = {
 .name = "VDO_ADMIN_STATE_RESUMING",
 .operating = true,
};
const struct admin_state_code *VDO_ADMIN_STATE_RESUMING = &VDO_CODE_RESUMING;

/**
 * get_next_state() - Determine the state which should be set after a given operation completes
 *                    based on the operation and the current state.
 * @operation The operation to be started.
 *
 * Return: The state to set when the operation completes or NULL if the operation can not be
 *         started in the current state.
 */
static const struct admin_state_code *get_next_state(const struct admin_state *state,
           const struct admin_state_code *operation)
{
 const struct admin_state_code *code = vdo_get_admin_state_code(state);

 if (code->operating)
  return NULL;

 if (operation == VDO_ADMIN_STATE_SAVING)
  return (code == VDO_ADMIN_STATE_NORMAL_OPERATION ? VDO_ADMIN_STATE_SAVED : NULL);

 if (operation == VDO_ADMIN_STATE_SUSPENDING) {
  return (code == VDO_ADMIN_STATE_NORMAL_OPERATION
   ? VDO_ADMIN_STATE_SUSPENDED
   : NULL);
 }

 if (operation == VDO_ADMIN_STATE_STOPPING)
  return (code == VDO_ADMIN_STATE_NORMAL_OPERATION ? VDO_ADMIN_STATE_STOPPED : NULL);

 if (operation == VDO_ADMIN_STATE_PRE_LOADING)
  return (code == VDO_ADMIN_STATE_INITIALIZED ? VDO_ADMIN_STATE_PRE_LOADED : NULL);

 if (operation == VDO_ADMIN_STATE_SUSPENDED_OPERATION) {
  return (((code == VDO_ADMIN_STATE_SUSPENDED) ||
    (code == VDO_ADMIN_STATE_SAVED)) ? code : NULL);
 }

 return VDO_ADMIN_STATE_NORMAL_OPERATION;
}

/**
 * vdo_finish_operation() - Finish the current operation.
 *
 * Will notify the operation waiter if there is one. This method should be used for operations
 * started with vdo_start_operation(). For operations which were started with vdo_start_draining(),
 * use vdo_finish_draining() instead.
 *
 * Return: true if there was an operation to finish.
 */
bool vdo_finish_operation(struct admin_state *state, int result)
{
 if (!vdo_get_admin_state_code(state)->operating)
  return false;

 state->complete = state->starting;
 if (state->waiter != NULL)
  vdo_set_completion_result(state->waiter, result);

 if (!state->starting) {
  vdo_set_admin_state_code(state, state->next_state);
  if (state->waiter != NULL)
   vdo_launch_completion(vdo_forget(state->waiter));
 }

 return true;
}

/**
 * begin_operation() - Begin an operation if it may be started given the current state.
 * @waiter A completion to notify when the operation is complete; may be NULL.
 * @initiator The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
 *
 * Return: VDO_SUCCESS or an error.
 */
static int __must_check begin_operation(struct admin_state *state,
     const struct admin_state_code *operation,
     struct vdo_completion *waiter,
     vdo_admin_initiator_fn initiator)
{
 int result;
 const struct admin_state_code *next_state = get_next_state(state, operation);

 if (next_state == NULL) {
  result = vdo_log_error_strerror(VDO_INVALID_ADMIN_STATE,
      "Can't start %s from %s",
      operation->name,
      vdo_get_admin_state_code(state)->name);
 } else if (state->waiter != NULL) {
  result = vdo_log_error_strerror(VDO_COMPONENT_BUSY,
      "Can't start %s with extant waiter",
      operation->name);
 } else {
  state->waiter = waiter;
  state->next_state = next_state;
  vdo_set_admin_state_code(state, operation);
  if (initiator != NULL) {
   state->starting = true;
   initiator(state);
   state->starting = false;
   if (state->complete)
    vdo_finish_operation(state, VDO_SUCCESS);
  }

  return VDO_SUCCESS;
 }

 if (waiter != NULL)
  vdo_continue_completion(waiter, result);

 return result;
}

/**
 * start_operation() - Start an operation if it may be started given the current state.
 * @waiter     A completion to notify when the operation is complete.
 * @initiator The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
 *
 * Return: true if the operation was started.
 */
static inline bool __must_check start_operation(struct admin_state *state,
      const struct admin_state_code *operation,
      struct vdo_completion *waiter,
      vdo_admin_initiator_fn initiator)
{
 return (begin_operation(state, operation, waiter, initiator) == VDO_SUCCESS);
}

/**
 * check_code() - Check the result of a state validation.
 * @valid true if the code is of an appropriate type.
 * @code The code which failed to be of the correct type.
 * @what What the code failed to be, for logging.
 * @waiter The completion to notify of the error; may be NULL.
 *
 * If the result failed, log an invalid state error and, if there is a waiter, notify it.
 *
 * Return: The result of the check.
 */
static bool check_code(bool valid, const struct admin_state_code *code, const char *what,
         struct vdo_completion *waiter)
{
 int result;

 if (valid)
  return true;

 result = vdo_log_error_strerror(VDO_INVALID_ADMIN_STATE,
     "%s is not a %s", code->name, what);
 if (waiter != NULL)
  vdo_continue_completion(waiter, result);

 return false;
}

/**
 * assert_vdo_drain_operation() - Check that an operation is a drain.
 * @waiter The completion to finish with an error if the operation is not a drain.
 *
 * Return: true if the specified operation is a drain.
 */
static bool __must_check assert_vdo_drain_operation(const struct admin_state_code *operation,
          struct vdo_completion *waiter)
{
 return check_code(operation->draining, operation, "drain operation", waiter);
}

/**
 * vdo_start_draining() - Initiate a drain operation if the current state permits it.
 * @operation The type of drain to initiate.
 * @waiter The completion to notify when the drain is complete.
 * @initiator The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
 *
 * Return: true if the drain was initiated, if not the waiter will be notified.
 */
bool vdo_start_draining(struct admin_state *state,
   const struct admin_state_code *operation,
   struct vdo_completion *waiter, vdo_admin_initiator_fn initiator)
{
 const struct admin_state_code *code = vdo_get_admin_state_code(state);

 if (!assert_vdo_drain_operation(operation, waiter))
  return false;

 if (code->quiescent) {
  vdo_launch_completion(waiter);
  return false;
 }

 if (!code->normal) {
  vdo_log_error_strerror(VDO_INVALID_ADMIN_STATE, "can't start %s from %s",
           operation->name, code->name);
  vdo_continue_completion(waiter, VDO_INVALID_ADMIN_STATE);
  return false;
 }

 return start_operation(state, operation, waiter, initiator);
}

/**
 * vdo_finish_draining() - Finish a drain operation if one was in progress.
 *
 * Return: true if the state was draining; will notify the waiter if so.
 */
bool vdo_finish_draining(struct admin_state *state)
{
 return vdo_finish_draining_with_result(state, VDO_SUCCESS);
}

/**
 * vdo_finish_draining_with_result() - Finish a drain operation with a status code.
 *
 * Return: true if the state was draining; will notify the waiter if so.
 */
bool vdo_finish_draining_with_result(struct admin_state *state, int result)
{
 return (vdo_is_state_draining(state) && vdo_finish_operation(state, result));
}

/**
 * vdo_assert_load_operation() - Check that an operation is a load.
 * @waiter The completion to finish with an error if the operation is not a load.
 *
 * Return: true if the specified operation is a load.
 */
bool vdo_assert_load_operation(const struct admin_state_code *operation,
          struct vdo_completion *waiter)
{
 return check_code(operation->loading, operation, "load operation", waiter);
}

/**
 * vdo_start_loading() - Initiate a load operation if the current state permits it.
 * @operation The type of load to initiate.
 * @waiter The completion to notify when the load is complete (may be NULL).
 * @initiator The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
 *
 * Return: true if the load was initiated, if not the waiter will be notified.
 */
bool vdo_start_loading(struct admin_state *state,
         const struct admin_state_code *operation,
         struct vdo_completion *waiter, vdo_admin_initiator_fn initiator)
{
 return (vdo_assert_load_operation(operation, waiter) &&
  start_operation(state, operation, waiter, initiator));
}

/**
 * vdo_finish_loading() - Finish a load operation if one was in progress.
 *
 * Return: true if the state was loading; will notify the waiter if so.
 */
bool vdo_finish_loading(struct admin_state *state)
{
 return vdo_finish_loading_with_result(state, VDO_SUCCESS);
}

/**
 * vdo_finish_loading_with_result() - Finish a load operation with a status code.
 * @result The result of the load operation.
 *
 * Return: true if the state was loading; will notify the waiter if so.
 */
bool vdo_finish_loading_with_result(struct admin_state *state, int result)
{
 return (vdo_is_state_loading(state) && vdo_finish_operation(state, result));
}

/**
 * assert_vdo_resume_operation() - Check whether an admin_state_code is a resume operation.
 * @waiter The completion to notify if the operation is not a resume operation; may be NULL.
 *
 * Return: true if the code is a resume operation.
 */
static bool __must_check assert_vdo_resume_operation(const struct admin_state_code *operation,
           struct vdo_completion *waiter)
{
 return check_code(operation == VDO_ADMIN_STATE_RESUMING, operation,
     "resume operation", waiter);
}

/**
 * vdo_start_resuming() - Initiate a resume operation if the current state permits it.
 * @operation The type of resume to start.
 * @waiter The completion to notify when the resume is complete (may be NULL).
 * @initiator The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
 *
 * Return: true if the resume was initiated, if not the waiter will be notified.
 */
bool vdo_start_resuming(struct admin_state *state,
   const struct admin_state_code *operation,
   struct vdo_completion *waiter, vdo_admin_initiator_fn initiator)
{
 return (assert_vdo_resume_operation(operation, waiter) &&
  start_operation(state, operation, waiter, initiator));
}

/**
 * vdo_finish_resuming() - Finish a resume operation if one was in progress.
 *
 * Return: true if the state was resuming; will notify the waiter if so.
 */
bool vdo_finish_resuming(struct admin_state *state)
{
 return vdo_finish_resuming_with_result(state, VDO_SUCCESS);
}

/**
 * vdo_finish_resuming_with_result() - Finish a resume operation with a status code.
 * @result The result of the resume operation.
 *
 * Return: true if the state was resuming; will notify the waiter if so.
 */
bool vdo_finish_resuming_with_result(struct admin_state *state, int result)
{
 return (vdo_is_state_resuming(state) && vdo_finish_operation(state, result));
}

/**
 * vdo_resume_if_quiescent() - Change the state to normal operation if the current state is
 *                             quiescent.
 *
 * Return: VDO_SUCCESS if the state resumed, VDO_INVALID_ADMIN_STATE otherwise.
 */
int vdo_resume_if_quiescent(struct admin_state *state)
{
 if (!vdo_is_state_quiescent(state))
  return VDO_INVALID_ADMIN_STATE;

 vdo_set_admin_state_code(state, VDO_ADMIN_STATE_NORMAL_OPERATION);
 return VDO_SUCCESS;
}

/**
 * vdo_start_operation() - Attempt to start an operation.
 *
 * Return: VDO_SUCCESS if the operation was started, VDO_INVALID_ADMIN_STATE if not
 */
int vdo_start_operation(struct admin_state *state,
   const struct admin_state_code *operation)
{
 return vdo_start_operation_with_waiter(state, operation, NULL, NULL);
}

/**
 * vdo_start_operation_with_waiter() - Attempt to start an operation.
 * @waiter the completion to notify when the operation completes or fails to start; may be NULL.
 * @initiator The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
 *
 * Return: VDO_SUCCESS if the operation was started, VDO_INVALID_ADMIN_STATE if not
 */
int vdo_start_operation_with_waiter(struct admin_state *state,
        const struct admin_state_code *operation,
        struct vdo_completion *waiter,
        vdo_admin_initiator_fn initiator)
{
 return (check_code(operation->operating, operation, "operation", waiter) ?
  begin_operation(state, operation, waiter, initiator) :
  VDO_INVALID_ADMIN_STATE);
}