diff options
| -rw-r--r-- | include/linux/frontswap.h | 28 | ||||
| -rw-r--r-- | mm/frontswap.c | 57 |
2 files changed, 33 insertions, 52 deletions
diff --git a/include/linux/frontswap.h b/include/linux/frontswap.h index d4f2987..6c49e1e 100644 --- a/include/linux/frontswap.h +++ b/include/linux/frontswap.h @@ -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) { diff --git a/mm/frontswap.c b/mm/frontswap.c index e44c9cb..2760b0f 100644 --- a/mm/frontswap.c +++ b/mm/frontswap.c @@ -27,14 +27,6 @@ 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 * effect converting frontswap into a writethrough cache. In this mode, @@ -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) +{ + 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) { - frontswap_clear(sis, 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; } |
