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staging: erofs: introduce erofs shrinker

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This patch adds a dedicated shrinker targeting to free unneeded
memory consumed by a number of erofs in-memory data structures.

Like F2FS and UBIFS, it also adds:
  - sbi->umount_mutex to avoid races on shrinker and put_super
  - sbi->shrinker_run_no to not revisit recently scaned objects

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Gao Xiang 2018-07-26 20:22:04 +08:00 committed by Greg Kroah-Hartman
parent 2497ee4129
commit a158131262
3 changed files with 101 additions and 6 deletions
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7
drivers/staging/erofs/internal.h
View File

@ -66,6 +66,7 @@ typedef u64 erofs_nid_t;
struct erofs_sb_info {
/* list for all registered superblocks, mainly for shrinker */
struct list_head list;
struct mutex umount_mutex;
u32 blocks;
u32 meta_blkaddr;
@ -93,6 +94,7 @@ struct erofs_sb_info {
char *dev_name;
unsigned int mount_opt;
unsigned int shrinker_run_no;
#ifdef CONFIG_EROFS_FAULT_INJECTION
struct erofs_fault_info fault_info; /* For fault injection */
@ -416,6 +418,11 @@ extern struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp);
extern void erofs_register_super(struct super_block *sb);
extern void erofs_unregister_super(struct super_block *sb);
extern unsigned long erofs_shrink_count(struct shrinker *shrink,
struct shrink_control *sc);
extern unsigned long erofs_shrink_scan(struct shrinker *shrink,
struct shrink_control *sc);
#ifndef lru_to_page
#define lru_to_page(head) (list_entry((head)->prev, struct page, lru))
#endif

15
drivers/staging/erofs/super.c
View File

@ -375,7 +375,9 @@ static void erofs_put_super(struct super_block *sb)
infoln("unmounted for %s", sbi->dev_name);
__putname(sbi->dev_name);
mutex_lock(&sbi->umount_mutex);
erofs_unregister_super(sb);
mutex_unlock(&sbi->umount_mutex);
kfree(sbi);
sb->s_fs_info = NULL;
@ -415,6 +417,12 @@ static void erofs_kill_sb(struct super_block *sb)
kill_block_super(sb);
}
static struct shrinker erofs_shrinker_info = {
.scan_objects = erofs_shrink_scan,
.count_objects = erofs_shrink_count,
.seeks = DEFAULT_SEEKS,
};
static struct file_system_type erofs_fs_type = {
.owner = THIS_MODULE,
.name = "erofs",
@ -435,6 +443,10 @@ static int __init erofs_module_init(void)
if (err)
goto icache_err;
err = register_shrinker(&erofs_shrinker_info);
if (err)
goto shrinker_err;
err = register_filesystem(&erofs_fs_type);
if (err)
goto fs_err;
@ -443,6 +455,8 @@ static int __init erofs_module_init(void)
return 0;
fs_err:
unregister_shrinker(&erofs_shrinker_info);
shrinker_err:
erofs_exit_inode_cache();
icache_err:
return err;
@ -451,6 +465,7 @@ icache_err:
static void __exit erofs_module_exit(void)
{
unregister_filesystem(&erofs_fs_type);
unregister_shrinker(&erofs_shrinker_info);
erofs_exit_inode_cache();
infoln("successfully finalize erofs");
}

85
drivers/staging/erofs/utils.c
View File

@ -29,20 +29,93 @@ struct page *erofs_allocpage(struct list_head *pool, gfp_t gfp)
return page;
}
static DEFINE_MUTEX(erofs_sb_list_lock);
/* 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);
/* global shrink count (for all mounted EROFS instances) */
static atomic_long_t erofs_global_shrink_cnt;
void erofs_register_super(struct super_block *sb)
{
mutex_lock(&erofs_sb_list_lock);
list_add(&EROFS_SB(sb)->list, &erofs_sb_list);
mutex_unlock(&erofs_sb_list_lock);
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)
{
mutex_lock(&erofs_sb_list_lock);
spin_lock(&erofs_sb_list_lock);
list_del(&EROFS_SB(sb)->list);
mutex_unlock(&erofs_sb_list_lock);
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;
/* add scan handlers here */
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;
}