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Commit f066ea23 authored by Bob Liu's avatar Bob Liu Committed by Linus Torvalds
Browse files

mm: frontswap: cleanup code 



After allowing tmem backends to build/run as modules, frontswap_enabled
always true if defined CONFIG_FRONTSWAP.  But frontswap_test() depends on
whether backend is registered, mv it into frontswap.c using fronstswap_ops
to make the decision.

frontswap_set/clear are not used outside frontswap, so don't export them.

Signed-off-by: default avatarBob Liu <lliubbo@gmail.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Andor Daam <andor.daam@googlemail.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Florian Schmaus <fschmaus@gmail.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Stefan Hengelein <ilendir@googlemail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1e01c968

include/linux/frontswap.h

+3 −25
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ extern void frontswap_writethrough(bool); 
#define FRONTSWAP_HAS_EXCLUSIVE_GETS

extern void frontswap_tmem_exclusive_gets(bool);



extern bool __frontswap_test(struct swap_info_struct *, pgoff_t);

extern void __frontswap_init(unsigned type);

extern int __frontswap_store(struct page *page);

extern int __frontswap_load(struct page *page);
@@ -29,26 +30,11 @@ extern void __frontswap_invalidate_page(unsigned, pgoff_t); 
extern void __frontswap_invalidate_area(unsigned);



#ifdef CONFIG_FRONTSWAP

#define frontswap_enabled (1)



static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)

{

	bool ret = false;



	if (frontswap_enabled && sis->frontswap_map)

		ret = test_bit(offset, sis->frontswap_map);

	return ret;

}



static inline void frontswap_set(struct swap_info_struct *sis, pgoff_t offset)

{

	if (frontswap_enabled && sis->frontswap_map)

		set_bit(offset, sis->frontswap_map);

}



static inline void frontswap_clear(struct swap_info_struct *sis, pgoff_t offset)

{

	if (frontswap_enabled && sis->frontswap_map)

		clear_bit(offset, sis->frontswap_map);

	return __frontswap_test(sis, offset);

}



static inline void frontswap_map_set(struct swap_info_struct *p,
@@ -71,14 +57,6 @@ static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset) 
	return false;

}



static inline void frontswap_set(struct swap_info_struct *sis, pgoff_t offset)

{

}



static inline void frontswap_clear(struct swap_info_struct *sis, pgoff_t offset)

{

}



static inline void frontswap_map_set(struct swap_info_struct *p,

				     unsigned long *map)

{

mm/frontswap.c

+30 −27
Original line number Diff line number Diff line
@@ -26,14 +26,6 @@ 
 */

static struct frontswap_ops *frontswap_ops __read_mostly;



/*

 * This global enablement flag reduces overhead on systems where frontswap_ops

 * has not been registered, so is preferred to the slower alternative: a

 * function call that checks a non-global.

 */

bool frontswap_enabled __read_mostly;

EXPORT_SYMBOL(frontswap_enabled);



/*

 * If enabled, frontswap_store will return failure even on success.  As

 * a result, the swap subsystem will always write the page to swap, in
@@ -128,8 +120,6 @@ struct frontswap_ops *frontswap_register_ops(struct frontswap_ops *ops) 
	struct frontswap_ops *old = frontswap_ops;

	int i;



	frontswap_enabled = true;



	for (i = 0; i < MAX_SWAPFILES; i++) {

		if (test_and_clear_bit(i, need_init))

			ops->init(i);
@@ -183,9 +173,21 @@ void __frontswap_init(unsigned type) 
}

EXPORT_SYMBOL(__frontswap_init);



static inline void __frontswap_clear(struct swap_info_struct *sis, pgoff_t offset)

bool __frontswap_test(struct swap_info_struct *sis,

				pgoff_t offset)

{

	frontswap_clear(sis, offset);

	bool ret = false;



	if (frontswap_ops && sis->frontswap_map)

		ret = test_bit(offset, sis->frontswap_map);

	return ret;

}

EXPORT_SYMBOL(__frontswap_test);



static inline void __frontswap_clear(struct swap_info_struct *sis,

				pgoff_t offset)

{

	clear_bit(offset, sis->frontswap_map);

	atomic_dec(&sis->frontswap_pages);

}
@@ -204,18 +206,20 @@ int __frontswap_store(struct page *page) 
	struct swap_info_struct *sis = swap_info[type];

	pgoff_t offset = swp_offset(entry);



	if (!frontswap_ops) {

		inc_frontswap_failed_stores();

	/*

	 * Return if no backend registed.

	 * Don't need to inc frontswap_failed_stores here.

	 */

	if (!frontswap_ops)

		return ret;

	}



	BUG_ON(!PageLocked(page));

	BUG_ON(sis == NULL);

	if (frontswap_test(sis, offset))

	if (__frontswap_test(sis, offset))

		dup = 1;

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

	if (ret == 0) {

		frontswap_set(sis, offset);

		set_bit(offset, sis->frontswap_map);

		inc_frontswap_succ_stores();

		if (!dup)

			atomic_inc(&sis->frontswap_pages);
@@ -248,18 +252,18 @@ int __frontswap_load(struct page *page) 
	struct swap_info_struct *sis = swap_info[type];

	pgoff_t offset = swp_offset(entry);



	if (!frontswap_ops)

		return ret;



	BUG_ON(!PageLocked(page));

	BUG_ON(sis == NULL);

	if (frontswap_test(sis, offset))

	/*

	 * __frontswap_test() will check whether there is backend registered

	 */

	if (__frontswap_test(sis, offset))

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

	if (ret == 0) {

		inc_frontswap_loads();

		if (frontswap_tmem_exclusive_gets_enabled) {

			SetPageDirty(page);

			frontswap_clear(sis, offset);

			__frontswap_clear(sis, offset);

		}

	}

	return ret;
@@ -274,11 +278,11 @@ void __frontswap_invalidate_page(unsigned type, pgoff_t offset) 
{

	struct swap_info_struct *sis = swap_info[type];



	if (!frontswap_ops)

		return;



	BUG_ON(sis == NULL);

	if (frontswap_test(sis, offset)) {

	/*

	 * __frontswap_test() will check whether there is backend registered

	 */

	if (__frontswap_test(sis, offset)) {

		frontswap_ops->invalidate_page(type, offset);

		__frontswap_clear(sis, offset);

		inc_frontswap_invalidates();
@@ -435,7 +439,6 @@ static int __init init_frontswap(void) 
	debugfs_create_u64("invalidates", S_IRUGO,

				root, &frontswap_invalidates);

#endif

	frontswap_enabled = 1;

	return 0;

}