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_URGENT_SLEEP_TIME	500	/* 500 ms */
 17#define DEF_GC_THREAD_MIN_SLEEP_TIME	30000	/* milliseconds */
 18#define DEF_GC_THREAD_MAX_SLEEP_TIME	60000
 19#define DEF_GC_THREAD_NOGC_SLEEP_TIME	300000	/* wait 5 min */
 20#define LIMIT_INVALID_BLOCK	40 /* percentage over total user space */
 21#define LIMIT_FREE_BLOCK	40 /* percentage over invalid + free space */
 22
 23#define DEF_GC_FAILED_PINNED_FILES	2048
 24
 25/* Search max. number of dirty segments to select a victim segment */
 26#define DEF_MAX_VICTIM_SEARCH 4096 /* covers 8GB */
 27
 28struct f2fs_gc_kthread {
 29	struct task_struct *f2fs_gc_task;
 30	wait_queue_head_t gc_wait_queue_head;
 31
 32	/* for gc sleep time */
 33	unsigned int urgent_sleep_time;
 34	unsigned int min_sleep_time;
 35	unsigned int max_sleep_time;
 36	unsigned int no_gc_sleep_time;
 37
 38	/* for changing gc mode */
 39	unsigned int gc_idle;
 40	unsigned int gc_urgent;
 41	unsigned int gc_wake;
 42};
 43
 44struct gc_inode_list {
 45	struct list_head ilist;
 46	struct radix_tree_root iroot;
 47};
 48
 49/*
 50 * inline functions
 51 */
 52static inline block_t free_user_blocks(struct f2fs_sb_info *sbi)
 53{
 54	if (free_segments(sbi) < overprovision_segments(sbi))
 55		return 0;
 56	else
 57		return (free_segments(sbi) - overprovision_segments(sbi))
 58			<< sbi->log_blocks_per_seg;
 59}
 60
 61static inline block_t limit_invalid_user_blocks(struct f2fs_sb_info *sbi)
 62{
 63	return (long)(sbi->user_block_count * LIMIT_INVALID_BLOCK) / 100;
 64}
 65
 66static inline block_t limit_free_user_blocks(struct f2fs_sb_info *sbi)
 67{
 68	block_t reclaimable_user_blocks = sbi->user_block_count -
 69		written_block_count(sbi);
 70	return (long)(reclaimable_user_blocks * LIMIT_FREE_BLOCK) / 100;
 71}
 72
 73static inline void increase_sleep_time(struct f2fs_gc_kthread *gc_th,
 74							unsigned int *wait)
 75{
 76	unsigned int min_time = gc_th->min_sleep_time;
 77	unsigned int max_time = gc_th->max_sleep_time;
 78
 79	if (*wait == gc_th->no_gc_sleep_time)
 80		return;
 81
 82	if ((long long)*wait + (long long)min_time > (long long)max_time)
 83		*wait = max_time;
 84	else
 85		*wait += min_time;
 86}
 87
 88static inline void decrease_sleep_time(struct f2fs_gc_kthread *gc_th,
 89							unsigned int *wait)
 90{
 91	unsigned int min_time = gc_th->min_sleep_time;
 92
 93	if (*wait == gc_th->no_gc_sleep_time)
 94		*wait = gc_th->max_sleep_time;
 95
 96	if ((long long)*wait - (long long)min_time < (long long)min_time)
 97		*wait = min_time;
 98	else
 99		*wait -= min_time;
100}
101
102static inline bool has_enough_invalid_blocks(struct f2fs_sb_info *sbi)
103{
104	block_t invalid_user_blocks = sbi->user_block_count -
105					written_block_count(sbi);
106	/*
107	 * Background GC is triggered with the following conditions.
108	 * 1. There are a number of invalid blocks.
109	 * 2. There is not enough free space.
110	 */
111	if (invalid_user_blocks > limit_invalid_user_blocks(sbi) &&
112			free_user_blocks(sbi) < limit_free_user_blocks(sbi))
113		return true;
114	return false;
115}