302 lines
6.9 KiB
C
302 lines
6.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* Copyright (C) 2018 HUAWEI, Inc.
|
|
* http://www.huawei.com/
|
|
* Created by Gao Xiang <gaoxiang25@huawei.com>
|
|
*/
|
|
#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);
|
|
DBG_BUGON(page_ref_count(page) != 1);
|
|
list_del(&page->lru);
|
|
} else {
|
|
page = alloc_page(gfp);
|
|
}
|
|
return page;
|
|
}
|
|
|
|
#if (EROFS_PCPUBUF_NR_PAGES > 0)
|
|
static struct {
|
|
u8 data[PAGE_SIZE * EROFS_PCPUBUF_NR_PAGES];
|
|
} ____cacheline_aligned_in_smp erofs_pcpubuf[NR_CPUS];
|
|
|
|
void *erofs_get_pcpubuf(unsigned int pagenr)
|
|
{
|
|
preempt_disable();
|
|
return &erofs_pcpubuf[smp_processor_id()].data[pagenr * PAGE_SIZE];
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_EROFS_FS_ZIP
|
|
/* global shrink count (for all mounted EROFS instances) */
|
|
static atomic_long_t erofs_global_shrink_cnt;
|
|
|
|
static int erofs_workgroup_get(struct erofs_workgroup *grp)
|
|
{
|
|
int o;
|
|
|
|
repeat:
|
|
o = erofs_wait_on_workgroup_freezed(grp);
|
|
if (o <= 0)
|
|
return -1;
|
|
|
|
if (atomic_cmpxchg(&grp->refcount, o, o + 1) != o)
|
|
goto repeat;
|
|
|
|
/* decrease refcount paired by erofs_workgroup_put */
|
|
if (o == 1)
|
|
atomic_long_dec(&erofs_global_shrink_cnt);
|
|
return 0;
|
|
}
|
|
|
|
struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
|
|
pgoff_t index)
|
|
{
|
|
struct erofs_sb_info *sbi = EROFS_SB(sb);
|
|
struct erofs_workgroup *grp;
|
|
|
|
repeat:
|
|
rcu_read_lock();
|
|
grp = xa_load(&sbi->managed_pslots, index);
|
|
if (grp) {
|
|
if (erofs_workgroup_get(grp)) {
|
|
/* prefer to relax rcu read side */
|
|
rcu_read_unlock();
|
|
goto repeat;
|
|
}
|
|
|
|
DBG_BUGON(index != grp->index);
|
|
}
|
|
rcu_read_unlock();
|
|
return grp;
|
|
}
|
|
|
|
struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb,
|
|
struct erofs_workgroup *grp)
|
|
{
|
|
struct erofs_sb_info *const sbi = EROFS_SB(sb);
|
|
struct erofs_workgroup *pre;
|
|
|
|
/*
|
|
* Bump up a reference count before making this visible
|
|
* to others for the XArray in order to avoid potential
|
|
* UAF without serialized by xa_lock.
|
|
*/
|
|
atomic_inc(&grp->refcount);
|
|
|
|
repeat:
|
|
xa_lock(&sbi->managed_pslots);
|
|
pre = __xa_cmpxchg(&sbi->managed_pslots, grp->index,
|
|
NULL, grp, GFP_NOFS);
|
|
if (pre) {
|
|
if (xa_is_err(pre)) {
|
|
pre = ERR_PTR(xa_err(pre));
|
|
} else if (erofs_workgroup_get(pre)) {
|
|
/* try to legitimize the current in-tree one */
|
|
xa_unlock(&sbi->managed_pslots);
|
|
cond_resched();
|
|
goto repeat;
|
|
}
|
|
atomic_dec(&grp->refcount);
|
|
grp = pre;
|
|
}
|
|
xa_unlock(&sbi->managed_pslots);
|
|
return 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;
|
|
}
|
|
|
|
static void erofs_workgroup_unfreeze_final(struct erofs_workgroup *grp)
|
|
{
|
|
erofs_workgroup_unfreeze(grp, 0);
|
|
__erofs_workgroup_free(grp);
|
|
}
|
|
|
|
static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
|
|
struct erofs_workgroup *grp)
|
|
{
|
|
/*
|
|
* If managed cache is on, refcount of workgroups
|
|
* themselves could be < 0 (freezed). In other words,
|
|
* there is no guarantee that all refcounts > 0.
|
|
*/
|
|
if (!erofs_workgroup_try_to_freeze(grp, 1))
|
|
return false;
|
|
|
|
/*
|
|
* Note that all cached pages should be unattached
|
|
* before deleted from the XArray. Otherwise some
|
|
* cached pages could be still attached to the orphan
|
|
* old workgroup when the new one is available in the tree.
|
|
*/
|
|
if (erofs_try_to_free_all_cached_pages(sbi, grp)) {
|
|
erofs_workgroup_unfreeze(grp, 1);
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* It's 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.
|
|
*/
|
|
DBG_BUGON(xa_erase(&sbi->managed_pslots, grp->index) != grp);
|
|
|
|
/*
|
|
* If managed cache is on, last refcount should indicate
|
|
* the related workstation.
|
|
*/
|
|
erofs_workgroup_unfreeze_final(grp);
|
|
return true;
|
|
}
|
|
|
|
static unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi,
|
|
unsigned long nr_shrink)
|
|
{
|
|
struct erofs_workgroup *grp;
|
|
unsigned int freed = 0;
|
|
unsigned long index;
|
|
|
|
xa_for_each(&sbi->managed_pslots, index, grp) {
|
|
/* try to shrink each valid workgroup */
|
|
if (!erofs_try_to_release_workgroup(sbi, grp))
|
|
continue;
|
|
|
|
++freed;
|
|
if (!--nr_shrink)
|
|
break;
|
|
}
|
|
return freed;
|
|
}
|
|
|
|
/* 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_shrinker_register(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_shrinker_unregister(struct super_block *sb)
|
|
{
|
|
struct erofs_sb_info *const sbi = EROFS_SB(sb);
|
|
|
|
mutex_lock(&sbi->umount_mutex);
|
|
/* clean up all remaining workgroups in memory */
|
|
erofs_shrink_workstation(sbi, ~0UL);
|
|
|
|
spin_lock(&erofs_sb_list_lock);
|
|
list_del(&sbi->list);
|
|
spin_unlock(&erofs_sb_list_lock);
|
|
mutex_unlock(&sbi->umount_mutex);
|
|
}
|
|
|
|
static unsigned long erofs_shrink_count(struct shrinker *shrink,
|
|
struct shrink_control *sc)
|
|
{
|
|
return atomic_long_read(&erofs_global_shrink_cnt);
|
|
}
|
|
|
|
static 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;
|
|
|
|
freed += erofs_shrink_workstation(sbi, nr - freed);
|
|
|
|
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;
|
|
}
|
|
|
|
static struct shrinker erofs_shrinker_info = {
|
|
.scan_objects = erofs_shrink_scan,
|
|
.count_objects = erofs_shrink_count,
|
|
.seeks = DEFAULT_SEEKS,
|
|
};
|
|
|
|
int __init erofs_init_shrinker(void)
|
|
{
|
|
return register_shrinker(&erofs_shrinker_info);
|
|
}
|
|
|
|
void erofs_exit_shrinker(void)
|
|
{
|
|
unregister_shrinker(&erofs_shrinker_info);
|
|
}
|
|
#endif /* !CONFIG_EROFS_FS_ZIP */
|
|
|