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/*
* f2fs shrinker support
* the basic infra was copied from fs/ubifs/shrinker.c
*
* Copyright (c) 2015 Motorola Mobility
* Copyright (c) 2015 Jaegeuk Kim <jaegeuk@kernel.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/fs.h>
#include <linux/f2fs_fs.h>
#include "f2fs.h"
static LIST_HEAD(f2fs_list);
static DEFINE_SPINLOCK(f2fs_list_lock);
static unsigned int shrinker_run_no;
static unsigned long __count_nat_entries(struct f2fs_sb_info *sbi)
{
return NM_I(sbi)->nat_cnt - NM_I(sbi)->dirty_nat_cnt;
}
static unsigned long __count_free_nids(struct f2fs_sb_info *sbi)
{
if (NM_I(sbi)->fcnt > NAT_ENTRY_PER_BLOCK)
return NM_I(sbi)->fcnt - NAT_ENTRY_PER_BLOCK;
return 0;
}
static unsigned long __count_extent_cache(struct f2fs_sb_info *sbi)
{
return atomic_read(&sbi->total_ext_tree) +
atomic_read(&sbi->total_ext_node);
}
unsigned long f2fs_shrink_count(struct shrinker *shrink,
struct shrink_control *sc)
{
struct f2fs_sb_info *sbi;
struct list_head *p;
unsigned long count = 0;
spin_lock(&f2fs_list_lock);
p = f2fs_list.next;
while (p != &f2fs_list) {
sbi = list_entry(p, struct f2fs_sb_info, s_list);
/* stop f2fs_put_super */
if (!mutex_trylock(&sbi->umount_mutex)) {
p = p->next;
continue;
}
spin_unlock(&f2fs_list_lock);
/* count extent cache entries */
count += __count_extent_cache(sbi);
/* shrink clean nat cache entries */
count += __count_nat_entries(sbi);
/* count free nids cache entries */
count += __count_free_nids(sbi);
spin_lock(&f2fs_list_lock);
p = p->next;
mutex_unlock(&sbi->umount_mutex);
}
spin_unlock(&f2fs_list_lock);
return count;
}
unsigned long f2fs_shrink_scan(struct shrinker *shrink,
struct shrink_control *sc)
{
unsigned long nr = sc->nr_to_scan;
struct f2fs_sb_info *sbi;
struct list_head *p;
unsigned int run_no;
unsigned long freed = 0;
spin_lock(&f2fs_list_lock);
do {
run_no = ++shrinker_run_no;
} while (run_no == 0);
p = f2fs_list.next;
while (p != &f2fs_list) {
sbi = list_entry(p, struct f2fs_sb_info, s_list);
if (sbi->shrinker_run_no == run_no)
break;
/* stop f2fs_put_super */
if (!mutex_trylock(&sbi->umount_mutex)) {
p = p->next;
continue;
}
spin_unlock(&f2fs_list_lock);
sbi->shrinker_run_no = run_no;
/* shrink extent cache entries */
freed += f2fs_shrink_extent_tree(sbi, nr >> 1);
/* shrink clean nat cache entries */
if (freed < nr)
freed += try_to_free_nats(sbi, nr - freed);
/* shrink free nids cache entries */
if (freed < nr)
freed += try_to_free_nids(sbi, nr - freed);
spin_lock(&f2fs_list_lock);
p = p->next;
list_move_tail(&sbi->s_list, &f2fs_list);
mutex_unlock(&sbi->umount_mutex);
if (freed >= nr)
break;
}
spin_unlock(&f2fs_list_lock);
return freed;
}
void f2fs_join_shrinker(struct f2fs_sb_info *sbi)
{
spin_lock(&f2fs_list_lock);
list_add_tail(&sbi->s_list, &f2fs_list);
spin_unlock(&f2fs_list_lock);
}
void f2fs_leave_shrinker(struct f2fs_sb_info *sbi)
{
f2fs_shrink_extent_tree(sbi, __count_extent_cache(sbi));
spin_lock(&f2fs_list_lock);
list_del(&sbi->s_list);
spin_unlock(&f2fs_list_lock);
}
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