// 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);
|
}
|
return page;
|
}
|
|
/* global shrink count (for all mounted EROFS instances) */
|
static atomic_long_t erofs_global_shrink_cnt;
|
|
#ifdef CONFIG_EROFS_FS_ZIP
|
|
/* radix_tree and the future XArray both don't use tagptr_t yet */
|
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 = radix_tree_exceptional_entry(grp);
|
grp = (void *)((unsigned long)grp &
|
~RADIX_TREE_EXCEPTIONAL_ENTRY);
|
|
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);
|
DBG_BUGON(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 shouldn't be broken or used before */
|
if (unlikely(atomic_read(&grp->refcount) != 1)) {
|
DBG_BUGON(1);
|
return -EINVAL;
|
}
|
|
err = radix_tree_preload(GFP_NOFS);
|
if (err)
|
return err;
|
|
sbi = EROFS_SB(sb);
|
erofs_workstn_lock(sbi);
|
|
if (tag)
|
grp = (void *)((unsigned long)grp |
|
1UL << RADIX_TREE_EXCEPTIONAL_SHIFT);
|
|
/*
|
* Bump up reference count before making this workgroup
|
* visible to other users in order to avoid potential UAF
|
* without serialized by erofs_workstn_lock.
|
*/
|
__erofs_workgroup_get(grp);
|
|
err = radix_tree_insert(&sbi->workstn_tree,
|
grp->index, grp);
|
if (unlikely(err))
|
/*
|
* it's safe to decrease since the workgroup isn't visible
|
* and refcount >= 2 (cannot be freezed).
|
*/
|
__erofs_workgroup_put(grp);
|
|
erofs_workstn_unlock(sbi);
|
radix_tree_preload_end();
|
return err;
|
}
|
|
extern void erofs_workgroup_free_rcu(struct erofs_workgroup *grp);
|
|
static void __erofs_workgroup_free(struct erofs_workgroup *grp)
|
{
|
atomic_long_dec(&erofs_global_shrink_cnt);
|
erofs_workgroup_free_rcu(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)
|
__erofs_workgroup_free(grp);
|
return count;
|
}
|
|
#ifdef EROFS_FS_HAS_MANAGED_CACHE
|
/* for cache-managed case, customized reclaim paths exist */
|
static void erofs_workgroup_unfreeze_final(struct erofs_workgroup *grp)
|
{
|
erofs_workgroup_unfreeze(grp, 0);
|
__erofs_workgroup_free(grp);
|
}
|
|
bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
|
struct erofs_workgroup *grp,
|
bool cleanup)
|
{
|
void *entry;
|
|
/*
|
* for managed cache enabled, the refcount of workgroups
|
* themselves could be < 0 (freezed). So there is no guarantee
|
* that all refcount > 0 if managed cache is enabled.
|
*/
|
if (!erofs_workgroup_try_to_freeze(grp, 1))
|
return false;
|
|
/*
|
* note that all cached pages should be unlinked
|
* before delete it from the radix tree.
|
* Otherwise some cached pages of an orphan old workgroup
|
* could be still linked after the new one is available.
|
*/
|
if (erofs_try_to_free_all_cached_pages(sbi, grp)) {
|
erofs_workgroup_unfreeze(grp, 1);
|
return false;
|
}
|
|
/*
|
* it is impossible to fail after the workgroup is freezed,
|
* however in order to avoid some race conditions, add a
|
* DBG_BUGON to observe this in advance.
|
*/
|
entry = radix_tree_delete(&sbi->workstn_tree, grp->index);
|
DBG_BUGON((void *)((unsigned long)entry &
|
~RADIX_TREE_EXCEPTIONAL_ENTRY) != grp);
|
|
/*
|
* if managed cache is enable, the last refcount
|
* should indicate the related workstation.
|
*/
|
erofs_workgroup_unfreeze_final(grp);
|
return true;
|
}
|
|
#else
|
/* for nocache case, no customized reclaim path at all */
|
bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
|
struct erofs_workgroup *grp,
|
bool cleanup)
|
{
|
int cnt = atomic_read(&grp->refcount);
|
void *entry;
|
|
DBG_BUGON(cnt <= 0);
|
DBG_BUGON(cleanup && cnt != 1);
|
|
if (cnt > 1)
|
return false;
|
|
entry = radix_tree_delete(&sbi->workstn_tree, grp->index);
|
DBG_BUGON((void *)((unsigned long)entry &
|
~RADIX_TREE_EXCEPTIONAL_ENTRY) != grp);
|
|
/* (rarely) could be grabbed again when freeing */
|
erofs_workgroup_put(grp);
|
return true;
|
}
|
|
#endif
|
|
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 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) {
|
struct erofs_workgroup *grp = (void *)
|
((unsigned long)batch[i] &
|
~RADIX_TREE_EXCEPTIONAL_ENTRY);
|
|
first_index = grp->index + 1;
|
|
/* try to shrink each valid workgroup */
|
if (!erofs_try_to_release_workgroup(sbi, grp, cleanup))
|
continue;
|
|
++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 - freed, 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;
|
}
|
