1/*
  2 * fs/f2fs/gc.h
  3 *
  4 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
  5 *             http://www.samsung.com/
  6 *
  7 * This program is free software; you can redistribute it and/or modify
  8 * it under the terms of the GNU General Public License version 2 as
  9 * published by the Free Software Foundation.
 10 */
 11#define GC_THREAD_MIN_WB_PAGES		1	/*
 12						 * a threshold to determine
 13						 * whether IO subsystem is idle
 14						 * or not
 15						 */
 16#define DEF_GC_THREAD_MIN_SLEEP_TIME	30000	/* milliseconds */
 17#define DEF_GC_THREAD_MAX_SLEEP_TIME	60000
 18#define DEF_GC_THREAD_NOGC_SLEEP_TIME	300000	/* wait 5 min */
 19#define LIMIT_INVALID_BLOCK	40 /* percentage over total user space */
 20#define LIMIT_FREE_BLOCK	40 /* percentage over invalid + free space */
 21
 22/* Search max. number of dirty segments to select a victim segment */
 23#define DEF_MAX_VICTIM_SEARCH 4096 /* covers 8GB */
 24
 25struct f2fs_gc_kthread {
 26	struct task_struct *f2fs_gc_task;
 27	wait_queue_head_t gc_wait_queue_head;
 28
 29	/* for gc sleep time */
 30	unsigned int min_sleep_time;
 31	unsigned int max_sleep_time;
 32	unsigned int no_gc_sleep_time;
 33
 34	/* for changing gc mode */
 35	unsigned int gc_idle;
 36};
 37
 38struct gc_inode_list {
 39	struct list_head ilist;
 40	struct radix_tree_root iroot;
 41};
 42
 43/*
 44 * inline functions
 45 */
 46static inline block_t free_user_blocks(struct f2fs_sb_info *sbi)
 47{
 48	if (free_segments(sbi) < overprovision_segments(sbi))
 49		return 0;
 50	else
 51		return (free_segments(sbi) - overprovision_segments(sbi))
 52			<< sbi->log_blocks_per_seg;
 53}
 54
 55static inline block_t limit_invalid_user_blocks(struct f2fs_sb_info *sbi)
 56{
 57	return (long)(sbi->user_block_count * LIMIT_INVALID_BLOCK) / 100;
 58}
 59
 60static inline block_t limit_free_user_blocks(struct f2fs_sb_info *sbi)
 61{
 62	block_t reclaimable_user_blocks = sbi->user_block_count -
 63		written_block_count(sbi);
 64	return (long)(reclaimable_user_blocks * LIMIT_FREE_BLOCK) / 100;
 65}
 66
 67static inline void increase_sleep_time(struct f2fs_gc_kthread *gc_th,
 68								long *wait)
 69{
 70	if (*wait == gc_th->no_gc_sleep_time)
 71		return;
 72
 73	*wait += gc_th->min_sleep_time;
 74	if (*wait > gc_th->max_sleep_time)
 75		*wait = gc_th->max_sleep_time;
 76}
 77
 78static inline void decrease_sleep_time(struct f2fs_gc_kthread *gc_th,
 79								long *wait)
 80{
 81	if (*wait == gc_th->no_gc_sleep_time)
 82		*wait = gc_th->max_sleep_time;
 83
 84	*wait -= gc_th->min_sleep_time;
 85	if (*wait <= gc_th->min_sleep_time)
 86		*wait = gc_th->min_sleep_time;
 87}
 88
 89static inline bool has_enough_invalid_blocks(struct f2fs_sb_info *sbi)
 90{
 91	block_t invalid_user_blocks = sbi->user_block_count -
 92					written_block_count(sbi);
 93	/*
 94	 * Background GC is triggered with the following conditions.
 95	 * 1. There are a number of invalid blocks.
 96	 * 2. There is not enough free space.
 97	 */
 98	if (invalid_user_blocks > limit_invalid_user_blocks(sbi) &&
 99			free_user_blocks(sbi) < limit_free_user_blocks(sbi))
100		return true;
101	return false;
102}