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 GC_THREAD_MIN_SLEEP_TIME        30000   /* milliseconds */
  17 #define GC_THREAD_MAX_SLEEP_TIME        60000
  18 #define 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       20
  24
  25 struct f2fs_gc_kthread {
  26         struct task_struct *f2fs_gc_task;
  27         wait_queue_head_t gc_wait_queue_head;
  28 };
  29
  30 struct inode_entry {
  31         struct list_head list;
  32         struct inode *inode;
  33 };
  34
  35 /*
  36  * inline functions
  37  */
  38 static inline block_t free_user_blocks(struct f2fs_sb_info *sbi)
  39 {
  40         if (free_segments(sbi) < overprovision_segments(sbi))
  41                 return 0;
  42         else
  43                 return (free_segments(sbi) - overprovision_segments(sbi))
  44                         << sbi->log_blocks_per_seg;
  45 }
  46
  47 static inline block_t limit_invalid_user_blocks(struct f2fs_sb_info *sbi)
  48 {
  49         return (long)(sbi->user_block_count * LIMIT_INVALID_BLOCK) / 100;
  50 }
  51
  52 static inline block_t limit_free_user_blocks(struct f2fs_sb_info *sbi)
  53 {
  54         block_t reclaimable_user_blocks = sbi->user_block_count -
  55                 written_block_count(sbi);
  56         return (long)(reclaimable_user_blocks * LIMIT_FREE_BLOCK) / 100;
  57 }
  58
  59 static inline long increase_sleep_time(long wait)
  60 {
  61         if (wait == GC_THREAD_NOGC_SLEEP_TIME)
  62                 return wait;
  63
  64         wait += GC_THREAD_MIN_SLEEP_TIME;
  65         if (wait > GC_THREAD_MAX_SLEEP_TIME)
  66                 wait = GC_THREAD_MAX_SLEEP_TIME;
  67         return wait;
  68 }
  69
  70 static inline long decrease_sleep_time(long wait)
  71 {
  72         if (wait == GC_THREAD_NOGC_SLEEP_TIME)
  73                 wait = GC_THREAD_MAX_SLEEP_TIME;
  74
  75         wait -= GC_THREAD_MIN_SLEEP_TIME;
  76         if (wait <= GC_THREAD_MIN_SLEEP_TIME)
  77                 wait = GC_THREAD_MIN_SLEEP_TIME;
  78         return wait;
  79 }
  80
  81 static inline bool has_enough_invalid_blocks(struct f2fs_sb_info *sbi)
  82 {
  83         block_t invalid_user_blocks = sbi->user_block_count -
  84                                         written_block_count(sbi);
  85         /*
  86          * Background GC is triggered with the following condition.
  87          * 1. There are a number of invalid blocks.
  88          * 2. There is not enough free space.
  89          */
  90         if (invalid_user_blocks > limit_invalid_user_blocks(sbi) &&
  91                         free_user_blocks(sbi) < limit_free_user_blocks(sbi))
  92                 return true;
  93         return false;
  94 }
  95
  96 static inline int is_idle(struct f2fs_sb_info *sbi)
  97 {
  98         struct block_device *bdev = sbi->sb->s_bdev;
  99         struct request_queue *q = bdev_get_queue(bdev);
 100         struct request_list *rl = &q->root_rl;
 101         return !(rl->count[BLK_RW_SYNC]) && !(rl->count[BLK_RW_ASYNC]);
 102 }