blob: ea8a962e5c9504a2c2f7f54e744b10da9bdc1048 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* linux/drivers/staging/erofs/utils.c
*
* Copyright (C) 2018 HUAWEI, Inc.
* http://www.huawei.com/
* Created by Gao Xiang <gaoxiang25@huawei.com>
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file COPYING in the main directory of the Linux
* distribution for more details.
*/
#include "internal.h"
#include <linux/pagevec.h>
struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp)
{
struct page *page;
if (!list_empty(pool)) {
page = lru_to_page(pool);
list_del(&page->lru);
} else {
page = alloc_pages(gfp | __GFP_NOFAIL, 0);
BUG_ON(page == NULL);
BUG_ON(page->mapping != NULL);
}
return page;
}
/* global shrink count (for all mounted EROFS instances) */
static atomic_long_t erofs_global_shrink_cnt;
#ifdef CONFIG_EROFS_FS_ZIP
struct erofs_workgroup *erofs_find_workgroup(
struct super_block *sb, pgoff_t index, bool *tag)
{
struct erofs_sb_info *sbi = EROFS_SB(sb);
struct erofs_workgroup *grp;
int oldcount;
repeat:
rcu_read_lock();
grp = radix_tree_lookup(&sbi->workstn_tree, index);
if (grp != NULL) {
*tag = xa_pointer_tag(grp);
grp = xa_untag_pointer(grp);
if (erofs_workgroup_get(grp, &oldcount)) {
/* prefer to relax rcu read side */
rcu_read_unlock();
goto repeat;
}
/* decrease refcount added by erofs_workgroup_put */
if (unlikely(oldcount == 1))
atomic_long_dec(&erofs_global_shrink_cnt);
BUG_ON(index != grp->index);
}
rcu_read_unlock();
return grp;
}
int erofs_register_workgroup(struct super_block *sb,
struct erofs_workgroup *grp,
bool tag)
{
struct erofs_sb_info *sbi;
int err;
/* grp->refcount should not < 1 */
BUG_ON(!atomic_read(&grp->refcount));
err = radix_tree_preload(GFP_NOFS);
if (err)
return err;
sbi = EROFS_SB(sb);
erofs_workstn_lock(sbi);
grp = xa_tag_pointer(grp, tag);
err = radix_tree_insert(&sbi->workstn_tree,
grp->index, grp);
if (!err) {
__erofs_workgroup_get(grp);
}
erofs_workstn_unlock(sbi);
radix_tree_preload_end();
return err;
}
extern void erofs_workgroup_free_rcu(struct erofs_workgroup *grp);
int erofs_workgroup_put(struct erofs_workgroup *grp)
{
int count = atomic_dec_return(&grp->refcount);
if (count == 1)
atomic_long_inc(&erofs_global_shrink_cnt);
else if (!count) {
atomic_long_dec(&erofs_global_shrink_cnt);
erofs_workgroup_free_rcu(grp);
}
return count;
}
unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi,
unsigned long nr_shrink,
bool cleanup)
{
pgoff_t first_index = 0;
void *batch[PAGEVEC_SIZE];
unsigned int freed = 0;
int i, found;
repeat:
erofs_workstn_lock(sbi);
found = radix_tree_gang_lookup(&sbi->workstn_tree,
batch, first_index, PAGEVEC_SIZE);
for (i = 0; i < found; ++i) {
int cnt;
struct erofs_workgroup *grp = xa_untag_pointer(batch[i]);
first_index = grp->index + 1;
cnt = atomic_read(&grp->refcount);
BUG_ON(cnt <= 0);
if (cleanup)
BUG_ON(cnt != 1);
#ifndef EROFS_FS_HAS_MANAGED_CACHE
else if (cnt > 1)
#else
if (!erofs_workgroup_try_to_freeze(grp, 1))
#endif
continue;
if (xa_untag_pointer(radix_tree_delete(&sbi->workstn_tree,
grp->index)) != grp) {
#ifdef EROFS_FS_HAS_MANAGED_CACHE
skip:
erofs_workgroup_unfreeze(grp, 1);
#endif
continue;
}
#ifdef EROFS_FS_HAS_MANAGED_CACHE
if (erofs_try_to_free_all_cached_pages(sbi, grp))
goto skip;
erofs_workgroup_unfreeze(grp, 1);
#endif
/* (rarely) grabbed again when freeing */
erofs_workgroup_put(grp);
++freed;
if (unlikely(!--nr_shrink))
break;
}
erofs_workstn_unlock(sbi);
if (i && nr_shrink)
goto repeat;
return freed;
}
#endif
/* protected by 'erofs_sb_list_lock' */
static unsigned int shrinker_run_no;
/* protects the mounted 'erofs_sb_list' */
static DEFINE_SPINLOCK(erofs_sb_list_lock);
static LIST_HEAD(erofs_sb_list);
void erofs_register_super(struct super_block *sb)
{
struct erofs_sb_info *sbi = EROFS_SB(sb);
mutex_init(&sbi->umount_mutex);
spin_lock(&erofs_sb_list_lock);
list_add(&sbi->list, &erofs_sb_list);
spin_unlock(&erofs_sb_list_lock);
}
void erofs_unregister_super(struct super_block *sb)
{
spin_lock(&erofs_sb_list_lock);
list_del(&EROFS_SB(sb)->list);
spin_unlock(&erofs_sb_list_lock);
}
unsigned long erofs_shrink_count(struct shrinker *shrink,
struct shrink_control *sc)
{
return atomic_long_read(&erofs_global_shrink_cnt);
}
unsigned long erofs_shrink_scan(struct shrinker *shrink,
struct shrink_control *sc)
{
struct erofs_sb_info *sbi;
struct list_head *p;
unsigned long nr = sc->nr_to_scan;
unsigned int run_no;
unsigned long freed = 0;
spin_lock(&erofs_sb_list_lock);
do
run_no = ++shrinker_run_no;
while (run_no == 0);
/* Iterate over all mounted superblocks and try to shrink them */
p = erofs_sb_list.next;
while (p != &erofs_sb_list) {
sbi = list_entry(p, struct erofs_sb_info, list);
/*
* We move the ones we do to the end of the list, so we stop
* when we see one we have already done.
*/
if (sbi->shrinker_run_no == run_no)
break;
if (!mutex_trylock(&sbi->umount_mutex)) {
p = p->next;
continue;
}
spin_unlock(&erofs_sb_list_lock);
sbi->shrinker_run_no = run_no;
#ifdef CONFIG_EROFS_FS_ZIP
freed += erofs_shrink_workstation(sbi, nr, false);
#endif
spin_lock(&erofs_sb_list_lock);
/* Get the next list element before we move this one */
p = p->next;
/*
* Move this one to the end of the list to provide some
* fairness.
*/
list_move_tail(&sbi->list, &erofs_sb_list);
mutex_unlock(&sbi->umount_mutex);
if (freed >= nr)
break;
}
spin_unlock(&erofs_sb_list_lock);
return freed;
}