fs/f2fs/gc.h

   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 MAX_VICTIM_SEARCH 4096 /* covers 8GB */
  24
  25 struct 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
  38 struct inode_entry {
  39         struct list_head list;
  40         struct inode *inode;
  41 };
  42
  43 /*
  44  * inline functions
  45  */
  46 static 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
  55 static 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
  60 static 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
  67 static inline long increase_sleep_time(struct f2fs_gc_kthread *gc_th, long wait)
  68 {
  69         if (wait == gc_th->no_gc_sleep_time)
  70                 return wait;
  71
  72         wait += gc_th->min_sleep_time;
  73         if (wait > gc_th->max_sleep_time)
  74                 wait = gc_th->max_sleep_time;
  75         return wait;
  76 }
  77
  78 static inline long decrease_sleep_time(struct f2fs_gc_kthread *gc_th, long wait)
  79 {
  80         if (wait == gc_th->no_gc_sleep_time)
  81                 wait = gc_th->max_sleep_time;
  82
  83         wait -= gc_th->min_sleep_time;
  84         if (wait <= gc_th->min_sleep_time)
  85                 wait = gc_th->min_sleep_time;
  86         return wait;
  87 }
  88
  89 static 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 condition.
  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 }
 103
 104 static inline int is_idle(struct f2fs_sb_info *sbi)
 105 {
 106         struct block_device *bdev = sbi->sb->s_bdev;
 107         struct request_queue *q = bdev_get_queue(bdev);
 108         struct request_list *rl = &q->root_rl;
 109         return !(rl->count[BLK_RW_SYNC]) && !(rl->count[BLK_RW_ASYNC]);
 110 }