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mm: frontswap: cleanup code

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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: Bob 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Bob Liu 2013-04-30 15:26:53 -07:00 committed by Linus Torvalds
parent 1e01c968db
commit f066ea230a
2 changed files with 33 additions and 52 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

28
include/linux/frontswap.h
View file

@ -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)
{

57
mm/frontswap.c
View file

@ -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;
}