fs/f2fs/shrinker.c

   1 /*
   2  * f2fs shrinker support
   3  *   the basic infra was copied from fs/ubifs/shrinker.c
   4  *
   5  * Copyright (c) 2015 Motorola Mobility
   6  * Copyright (c) 2015 Jaegeuk Kim <jaegeuk@kernel.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #include <linux/fs.h>
  13 #include <linux/f2fs_fs.h>
  14
  15 #include "f2fs.h"
  16
  17 static LIST_HEAD(f2fs_list);
  18 static DEFINE_SPINLOCK(f2fs_list_lock);
  19 static unsigned int shrinker_run_no;
  20
  21 static unsigned long __count_nat_entries(struct f2fs_sb_info *sbi)
  22 {
  23         return NM_I(sbi)->nat_cnt - NM_I(sbi)->dirty_nat_cnt;
  24 }
  25
  26 static unsigned long __count_free_nids(struct f2fs_sb_info *sbi)
  27 {
  28         if (NM_I(sbi)->fcnt > NAT_ENTRY_PER_BLOCK)
  29                 return NM_I(sbi)->fcnt - NAT_ENTRY_PER_BLOCK;
  30         return 0;
  31 }
  32
  33 static unsigned long __count_extent_cache(struct f2fs_sb_info *sbi)
  34 {
  35         return sbi->total_ext_tree + atomic_read(&sbi->total_ext_node);
  36 }
  37
  38 unsigned long f2fs_shrink_count(struct shrinker *shrink,
  39                                 struct shrink_control *sc)
  40 {
  41         struct f2fs_sb_info *sbi;
  42         struct list_head *p;
  43         unsigned long count = 0;
  44
  45         spin_lock(&f2fs_list_lock);
  46         p = f2fs_list.next;
  47         while (p != &f2fs_list) {
  48                 sbi = list_entry(p, struct f2fs_sb_info, s_list);
  49
  50                 /* stop f2fs_put_super */
  51                 if (!mutex_trylock(&sbi->umount_mutex)) {
  52                         p = p->next;
  53                         continue;
  54                 }
  55                 spin_unlock(&f2fs_list_lock);
  56
  57                 /* count extent cache entries */
  58                 count += __count_extent_cache(sbi);
  59
  60                 /* shrink clean nat cache entries */
  61                 count += __count_nat_entries(sbi);
  62
  63                 /* count free nids cache entries */
  64                 count += __count_free_nids(sbi);
  65
  66                 spin_lock(&f2fs_list_lock);
  67                 p = p->next;
  68                 mutex_unlock(&sbi->umount_mutex);
  69         }
  70         spin_unlock(&f2fs_list_lock);
  71         return count;
  72 }
  73
  74 unsigned long f2fs_shrink_scan(struct shrinker *shrink,
  75                                 struct shrink_control *sc)
  76 {
  77         unsigned long nr = sc->nr_to_scan;
  78         struct f2fs_sb_info *sbi;
  79         struct list_head *p;
  80         unsigned int run_no;
  81         unsigned long freed = 0;
  82
  83         spin_lock(&f2fs_list_lock);
  84         do {
  85                 run_no = ++shrinker_run_no;
  86         } while (run_no == 0);
  87         p = f2fs_list.next;
  88         while (p != &f2fs_list) {
  89                 sbi = list_entry(p, struct f2fs_sb_info, s_list);
  90
  91                 if (sbi->shrinker_run_no == run_no)
  92                         break;
  93
  94                 /* stop f2fs_put_super */
  95                 if (!mutex_trylock(&sbi->umount_mutex)) {
  96                         p = p->next;
  97                         continue;
  98                 }
  99                 spin_unlock(&f2fs_list_lock);
 100
 101                 sbi->shrinker_run_no = run_no;
 102
 103                 /* shrink extent cache entries */
 104                 freed += f2fs_shrink_extent_tree(sbi, nr >> 1);
 105
 106                 /* shrink clean nat cache entries */
 107                 if (freed < nr)
 108                         freed += try_to_free_nats(sbi, nr - freed);
 109
 110                 /* shrink free nids cache entries */
 111                 if (freed < nr)
 112                         freed += try_to_free_nids(sbi, nr - freed);
 113
 114                 spin_lock(&f2fs_list_lock);
 115                 p = p->next;
 116                 list_move_tail(&sbi->s_list, &f2fs_list);
 117                 mutex_unlock(&sbi->umount_mutex);
 118                 if (freed >= nr)
 119                         break;
 120         }
 121         spin_unlock(&f2fs_list_lock);
 122         return freed;
 123 }
 124
 125 void f2fs_join_shrinker(struct f2fs_sb_info *sbi)
 126 {
 127         spin_lock(&f2fs_list_lock);
 128         list_add_tail(&sbi->s_list, &f2fs_list);
 129         spin_unlock(&f2fs_list_lock);
 130 }
 131
 132 void f2fs_leave_shrinker(struct f2fs_sb_info *sbi)
 133 {
 134         f2fs_shrink_extent_tree(sbi, __count_extent_cache(sbi));
 135
 136         spin_lock(&f2fs_list_lock);
 137         list_del(&sbi->s_list);
 138         spin_unlock(&f2fs_list_lock);
 139 }