Commit 1da0d94a authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Linus Torvalds
Browse files

frontswap: remove support for multiple ops 

There is only a single instance of frontswap ops in the kernel, so
simplify the frontswap code by removing support for multiple operations.

Link: https://lkml.kernel.org/r/20211224062246.1258487-13-hch@lst.de


Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 633423a0

include/linux/frontswap.h

+1 −2
Original line number Diff line number Diff line
@@ -13,10 +13,9 @@ struct frontswap_ops { 
	int (*load)(unsigned, pgoff_t, struct page *); /* load a page */

	void (*invalidate_page)(unsigned, pgoff_t); /* page no longer needed */

	void (*invalidate_area)(unsigned); /* swap type just swapoff'ed */

	struct frontswap_ops *next; /* private pointer to next ops */

};



extern void frontswap_register_ops(struct frontswap_ops *ops);

int frontswap_register_ops(const struct frontswap_ops *ops);



extern void frontswap_init(unsigned type, unsigned long *map);

extern int __frontswap_store(struct page *page);

mm/frontswap.c

+12 −38
Original line number Diff line number Diff line
@@ -27,10 +27,7 @@ DEFINE_STATIC_KEY_FALSE(frontswap_enabled_key); 
 * may be registered, but implementations can never deregister.  This

 * is a simple singly-linked list of all registered implementations.

 */

static struct frontswap_ops *frontswap_ops __read_mostly;



#define for_each_frontswap_ops(ops)		\

	for ((ops) = frontswap_ops; (ops); (ops) = (ops)->next)

static const struct frontswap_ops *frontswap_ops __read_mostly;



#ifdef CONFIG_DEBUG_FS

/*
@@ -97,18 +94,14 @@ static inline void inc_frontswap_invalidates(void) { } 
/*

 * Register operations for frontswap

 */

void frontswap_register_ops(struct frontswap_ops *ops)

int frontswap_register_ops(const struct frontswap_ops *ops)

{

	/*

	 * Setting frontswap_ops must happen after the ops->init() calls

	 * above; cmpxchg implies smp_mb() which will ensure the init is

	 * complete at this point.

	 */

	do {

		ops->next = frontswap_ops;

	} while (cmpxchg(&frontswap_ops, ops->next, ops) != ops->next);

	if (frontswap_ops)

		return -EINVAL;



	frontswap_ops = ops;

	static_branch_inc(&frontswap_enabled_key);

	return 0;

}



/*
@@ -117,7 +110,6 @@ void frontswap_register_ops(struct frontswap_ops *ops) 
void frontswap_init(unsigned type, unsigned long *map)

{

	struct swap_info_struct *sis = swap_info[type];

	struct frontswap_ops *ops;



	VM_BUG_ON(sis == NULL);
@@ -133,9 +125,7 @@ void frontswap_init(unsigned type, unsigned long *map) 
	 * p->frontswap set to something valid to work properly.

	 */

	frontswap_map_set(sis, map);



	for_each_frontswap_ops(ops)

		ops->init(type);

	frontswap_ops->init(type);

}



static bool __frontswap_test(struct swap_info_struct *sis,
@@ -174,7 +164,6 @@ int __frontswap_store(struct page *page) 
	int type = swp_type(entry);

	struct swap_info_struct *sis = swap_info[type];

	pgoff_t offset = swp_offset(entry);

	struct frontswap_ops *ops;



	VM_BUG_ON(!frontswap_ops);

	VM_BUG_ON(!PageLocked(page));
@@ -188,16 +177,10 @@ int __frontswap_store(struct page *page) 
	 */

	if (__frontswap_test(sis, offset)) {

		__frontswap_clear(sis, offset);

		for_each_frontswap_ops(ops)

			ops->invalidate_page(type, offset);

		frontswap_ops->invalidate_page(type, offset);

	}



	/* Try to store in each implementation, until one succeeds. */

	for_each_frontswap_ops(ops) {

		ret = ops->store(type, offset, page);

		if (!ret) /* successful store */

			break;

	}

	ret = frontswap_ops->store(type, offset, page);

	if (ret == 0) {

		__frontswap_set(sis, offset);

		inc_frontswap_succ_stores();
@@ -220,7 +203,6 @@ int __frontswap_load(struct page *page) 
	int type = swp_type(entry);

	struct swap_info_struct *sis = swap_info[type];

	pgoff_t offset = swp_offset(entry);

	struct frontswap_ops *ops;



	VM_BUG_ON(!frontswap_ops);

	VM_BUG_ON(!PageLocked(page));
@@ -230,11 +212,7 @@ int __frontswap_load(struct page *page) 
		return -1;



	/* Try loading from each implementation, until one succeeds. */

	for_each_frontswap_ops(ops) {

		ret = ops->load(type, offset, page);

		if (!ret) /* successful load */

			break;

	}

	ret = frontswap_ops->load(type, offset, page);

	if (ret == 0)

		inc_frontswap_loads();

	return ret;
@@ -247,7 +225,6 @@ int __frontswap_load(struct page *page) 
void __frontswap_invalidate_page(unsigned type, pgoff_t offset)

{

	struct swap_info_struct *sis = swap_info[type];

	struct frontswap_ops *ops;



	VM_BUG_ON(!frontswap_ops);

	VM_BUG_ON(sis == NULL);
@@ -255,8 +232,7 @@ void __frontswap_invalidate_page(unsigned type, pgoff_t offset) 
	if (!__frontswap_test(sis, offset))

		return;



	for_each_frontswap_ops(ops)

		ops->invalidate_page(type, offset);

	frontswap_ops->invalidate_page(type, offset);

	__frontswap_clear(sis, offset);

	inc_frontswap_invalidates();

}
@@ -268,7 +244,6 @@ void __frontswap_invalidate_page(unsigned type, pgoff_t offset) 
void __frontswap_invalidate_area(unsigned type)

{

	struct swap_info_struct *sis = swap_info[type];

	struct frontswap_ops *ops;



	VM_BUG_ON(!frontswap_ops);

	VM_BUG_ON(sis == NULL);
@@ -276,8 +251,7 @@ void __frontswap_invalidate_area(unsigned type) 
	if (sis->frontswap_map == NULL)

		return;



	for_each_frontswap_ops(ops)

		ops->invalidate_area(type);

	frontswap_ops->invalidate_area(type);

	atomic_set(&sis->frontswap_pages, 0);

	bitmap_zero(sis->frontswap_map, sis->max);

}

mm/zswap.c

+6 −2
Original line number Diff line number Diff line
@@ -1378,7 +1378,7 @@ static void zswap_frontswap_init(unsigned type) 
	zswap_trees[type] = tree;

}



static struct frontswap_ops zswap_frontswap_ops = {

static const struct frontswap_ops zswap_frontswap_ops = {

	.store = zswap_frontswap_store,

	.load = zswap_frontswap_load,

	.invalidate_page = zswap_frontswap_invalidate_page,
@@ -1475,11 +1475,15 @@ static int __init init_zswap(void) 
	if (!shrink_wq)

		goto fallback_fail;



	frontswap_register_ops(&zswap_frontswap_ops);

	ret = frontswap_register_ops(&zswap_frontswap_ops);

	if (ret)

		goto destroy_wq;

	if (zswap_debugfs_init())

		pr_warn("debugfs initialization failed\n");

	return 0;



destroy_wq:

	destroy_workqueue(shrink_wq);

fallback_fail:

	if (pool)

		zswap_pool_destroy(pool);