diff options
| -rw-r--r-- | drivers/xen/xen-selfballoon.c | 4 | ||||
| -rw-r--r-- | include/linux/frontswap.h | 34 | ||||
| -rw-r--r-- | mm/frontswap.c | 35 | ||||
| -rw-r--r-- | mm/swapfile.c | 2 |
4 files changed, 38 insertions, 37 deletions
diff --git a/drivers/xen/xen-selfballoon.c b/drivers/xen/xen-selfballoon.c index 53a085f..6662071 100644 --- a/drivers/xen/xen-selfballoon.c +++ b/drivers/xen/xen-selfballoon.c @@ -195,7 +195,7 @@ static void selfballoon_process(struct work_struct *work) MB2PAGES(selfballoon_reserved_mb); #ifdef CONFIG_FRONTSWAP /* allow space for frontswap pages to be repatriated */ - if (frontswap_selfshrinking && frontswap_enabled) + if (frontswap_selfshrinking) goal_pages += frontswap_curr_pages(); #endif if (cur_pages > goal_pages) @@ -230,7 +230,7 @@ static void selfballoon_process(struct work_struct *work) reset_timer = true; } #ifdef CONFIG_FRONTSWAP - if (frontswap_selfshrinking && frontswap_enabled) { + if (frontswap_selfshrinking) { frontswap_selfshrink(); reset_timer = true; } diff --git a/include/linux/frontswap.h b/include/linux/frontswap.h index e65ef95..c46d2aa 100644 --- a/include/linux/frontswap.h +++ b/include/linux/frontswap.h @@ -4,6 +4,7 @@ #include <linux/swap.h> #include <linux/mm.h> #include <linux/bitops.h> +#include <linux/jump_label.h> struct frontswap_ops { void (*init)(unsigned); /* this swap type was just swapon'ed */ @@ -14,7 +15,6 @@ struct frontswap_ops { struct frontswap_ops *next; /* private pointer to next ops */ }; -extern bool frontswap_enabled; extern void frontswap_register_ops(struct frontswap_ops *ops); extern void frontswap_shrink(unsigned long); extern unsigned long frontswap_curr_pages(void); @@ -30,7 +30,12 @@ extern void __frontswap_invalidate_page(unsigned, pgoff_t); extern void __frontswap_invalidate_area(unsigned); #ifdef CONFIG_FRONTSWAP -#define frontswap_enabled (1) +extern struct static_key_false frontswap_enabled_key; + +static inline bool frontswap_enabled(void) +{ + return static_branch_unlikely(&frontswap_enabled_key); +} static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset) { @@ -50,7 +55,10 @@ static inline unsigned long *frontswap_map_get(struct swap_info_struct *p) #else /* all inline routines become no-ops and all externs are ignored */ -#define frontswap_enabled (0) +static inline bool frontswap_enabled(void) +{ + return false; +} static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset) { @@ -70,37 +78,35 @@ static inline unsigned long *frontswap_map_get(struct swap_info_struct *p) static inline int frontswap_store(struct page *page) { - int ret = -1; + if (frontswap_enabled()) + return __frontswap_store(page); - if (frontswap_enabled) - ret = __frontswap_store(page); - return ret; + return -1; } static inline int frontswap_load(struct page *page) { - int ret = -1; + if (frontswap_enabled()) + return __frontswap_load(page); - if (frontswap_enabled) - ret = __frontswap_load(page); - return ret; + return -1; } static inline void frontswap_invalidate_page(unsigned type, pgoff_t offset) { - if (frontswap_enabled) + if (frontswap_enabled()) __frontswap_invalidate_page(type, offset); } static inline void frontswap_invalidate_area(unsigned type) { - if (frontswap_enabled) + if (frontswap_enabled()) __frontswap_invalidate_area(type); } static inline void frontswap_init(unsigned type, unsigned long *map) { - if (frontswap_enabled) + if (frontswap_enabled()) __frontswap_init(type, map); } diff --git a/mm/frontswap.c b/mm/frontswap.c index 27a9924..fec8b50 100644 --- a/mm/frontswap.c +++ b/mm/frontswap.c @@ -20,6 +20,8 @@ #include <linux/frontswap.h> #include <linux/swapfile.h> +DEFINE_STATIC_KEY_FALSE(frontswap_enabled_key); + /* * frontswap_ops are added by frontswap_register_ops, and provide the * frontswap "backend" implementation functions. Multiple implementations @@ -139,6 +141,8 @@ void frontswap_register_ops(struct frontswap_ops *ops) ops->next = frontswap_ops; } while (cmpxchg(&frontswap_ops, ops->next, ops) != ops->next); + static_branch_inc(&frontswap_enabled_key); + spin_lock(&swap_lock); plist_for_each_entry(si, &swap_active_head, list) { if (si->frontswap_map) @@ -189,7 +193,7 @@ void __frontswap_init(unsigned type, unsigned long *map) struct swap_info_struct *sis = swap_info[type]; struct frontswap_ops *ops; - BUG_ON(sis == NULL); + VM_BUG_ON(sis == NULL); /* * p->frontswap is a bitmap that we MUST have to figure out which page @@ -248,15 +252,9 @@ int __frontswap_store(struct page *page) pgoff_t offset = swp_offset(entry); struct frontswap_ops *ops; - /* - * Return if no backend registed. - * Don't need to inc frontswap_failed_stores here. - */ - if (!frontswap_ops) - return -1; - - BUG_ON(!PageLocked(page)); - BUG_ON(sis == NULL); + VM_BUG_ON(!frontswap_ops); + VM_BUG_ON(!PageLocked(page)); + VM_BUG_ON(sis == NULL); /* * If a dup, we must remove the old page first; we can't leave the @@ -303,11 +301,10 @@ int __frontswap_load(struct page *page) pgoff_t offset = swp_offset(entry); struct frontswap_ops *ops; - if (!frontswap_ops) - return -1; + VM_BUG_ON(!frontswap_ops); + VM_BUG_ON(!PageLocked(page)); + VM_BUG_ON(sis == NULL); - BUG_ON(!PageLocked(page)); - BUG_ON(sis == NULL); if (!__frontswap_test(sis, offset)) return -1; @@ -337,10 +334,9 @@ void __frontswap_invalidate_page(unsigned type, pgoff_t offset) struct swap_info_struct *sis = swap_info[type]; struct frontswap_ops *ops; - if (!frontswap_ops) - return; + VM_BUG_ON(!frontswap_ops); + VM_BUG_ON(sis == NULL); - BUG_ON(sis == NULL); if (!__frontswap_test(sis, offset)) return; @@ -360,10 +356,9 @@ void __frontswap_invalidate_area(unsigned type) struct swap_info_struct *sis = swap_info[type]; struct frontswap_ops *ops; - if (!frontswap_ops) - return; + VM_BUG_ON(!frontswap_ops); + VM_BUG_ON(sis == NULL); - BUG_ON(sis == NULL); if (sis->frontswap_map == NULL) return; diff --git a/mm/swapfile.c b/mm/swapfile.c index 031713ab..78cfa29 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2493,7 +2493,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) goto bad_swap; } /* frontswap enabled? set up bit-per-page map for frontswap */ - if (frontswap_enabled) + if (IS_ENABLED(CONFIG_FRONTSWAP)) frontswap_map = vzalloc(BITS_TO_LONGS(maxpages) * sizeof(long)); if (p->bdev &&(swap_flags & SWAP_FLAG_DISCARD) && swap_discardable(p)) { |
