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Commit a1581312 authored by Gao Xiang's avatar Gao Xiang Committed by Greg Kroah-Hartman
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staging: erofs: introduce erofs shrinker 



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: default avatarGao Xiang <gaoxiang25@huawei.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2497ee41

drivers/staging/erofs/internal.h

+7 −0
Original line number Diff line number Diff line
@@ -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

drivers/staging/erofs/super.c

+15 −0
Original line number Diff line number Diff line
@@ -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 @@ static int __init erofs_module_init(void) 
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");

}

drivers/staging/erofs/utils.c

+79 −6
Original line number Diff line number Diff line
@@ -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;

}