/* SPDX-License-Identifier: GPL-2.0 */

  #ifndef _LINUX_SWAP_SLOTS_H
  #define _LINUX_SWAP_SLOTS_H
  
  #include <linux/swap.h>
  #include <linux/spinlock.h>
  #include <linux/mutex.h>
  
  #define SWAP_SLOTS_CACHE_SIZE			SWAP_BATCH
  #define THRESHOLD_ACTIVATE_SWAP_SLOTS_CACHE	(5*SWAP_SLOTS_CACHE_SIZE)
  #define THRESHOLD_DEACTIVATE_SWAP_SLOTS_CACHE	(2*SWAP_SLOTS_CACHE_SIZE)
  
  struct swap_slots_cache {
  	bool		lock_initialized;
  	struct mutex	alloc_lock; /* protects slots, nr, cur */
  	swp_entry_t	*slots;
  	int		nr;
  	int		cur;
  	spinlock_t	free_lock;  /* protects slots_ret, n_ret */
  	swp_entry_t	*slots_ret;
  	int		n_ret;
  };
  
  void disable_swap_slots_cache_lock(void);
  void reenable_swap_slots_cache_unlock(void);

  void enable_swap_slots_cache(void);

  int free_swap_slot(swp_entry_t entry);

  extern bool swap_slot_cache_enabled;

  #endif /* _LINUX_SWAP_SLOTS_H */