blob: e146d09151af4188efe4cb7bf2ad4a938b8596af [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2018 HUAWEI, Inc.
* https://www.huawei.com/
*/
#include "internal.h"
struct page *erofs_allocpage(struct page **pagepool, gfp_t gfp)
{
struct page *page = *pagepool;
if (page) {
DBG_BUGON(page_ref_count(page) != 1);
*pagepool = (struct page *)page_private(page);
} else {
page = alloc_page(gfp);
}
return page;
}
void erofs_release_pages(struct page **pagepool)
{
while (*pagepool) {
struct page *page = *pagepool;
*pagepool = (struct page *)page_private(page);
put_page(page);
}
}
#ifdef CONFIG_EROFS_FS_ZIP
/* global shrink count (for all mounted EROFS instances) */
static atomic_long_t erofs_global_shrink_cnt;
static bool erofs_workgroup_get(struct erofs_workgroup *grp)
{
if (lockref_get_not_zero(&grp->lockref))
return true;
spin_lock(&grp->lockref.lock);
if (__lockref_is_dead(&grp->lockref)) {
spin_unlock(&grp->lockref.lock);
return false;
}
if (!grp->lockref.count++)
atomic_long_dec(&erofs_global_shrink_cnt);
spin_unlock(&grp->lockref.lock);
return true;
}
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;
DBG_BUGON(grp->lockref.count < 1);
repeat:
xa_lock(&sbi->managed_pslots);
pre = __xa_cmpxchg(&sbi->managed_pslots, grp->index,
NULL, grp, GFP_KERNEL);
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;
}
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);
}
void erofs_workgroup_put(struct erofs_workgroup *grp)
{
if (lockref_put_or_lock(&grp->lockref))
return;
DBG_BUGON(__lockref_is_dead(&grp->lockref));
if (grp->lockref.count == 1)
atomic_long_inc(&erofs_global_shrink_cnt);
--grp->lockref.count;
spin_unlock(&grp->lockref.lock);
}
static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
struct erofs_workgroup *grp)
{
int free = false;
spin_lock(&grp->lockref.lock);
if (grp->lockref.count)
goto out;
/*
* Note that all cached pages should be detached 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))
goto out;
/*
* 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);
lockref_mark_dead(&grp->lockref);
free = true;
out:
spin_unlock(&grp->lockref.lock);
if (free)
__erofs_workgroup_free(grp);
return free;
}
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_lock(&sbi->managed_pslots);
xa_for_each(&sbi->managed_pslots, index, grp) {
/* try to shrink each valid workgroup */
if (!erofs_try_to_release_workgroup(sbi, grp))
continue;
xa_unlock(&sbi->managed_pslots);
++freed;
if (!--nr_shrink)
return freed;
xa_lock(&sbi->managed_pslots);
}
xa_unlock(&sbi->managed_pslots);
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;
int __init erofs_init_shrinker(void)
{
erofs_shrinker_info = shrinker_alloc(0, "erofs-shrinker");
if (!erofs_shrinker_info)
return -ENOMEM;
erofs_shrinker_info->count_objects = erofs_shrink_count;
erofs_shrinker_info->scan_objects = erofs_shrink_scan;
shrinker_register(erofs_shrinker_info);
return 0;
}
void erofs_exit_shrinker(void)
{
shrinker_free(erofs_shrinker_info);
}
#endif /* !CONFIG_EROFS_FS_ZIP */