From f066ea230a65f939afc354beae62716ab5f0e645 Mon Sep 17 00:00:00 2001 From: Bob Liu Date: Tue, 30 Apr 2013 15:26:53 -0700 Subject: 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: Bob Liu Cc: Wanpeng Li Cc: Andor Daam Cc: Dan Magenheimer Cc: Florian Schmaus Cc: Konrad Rzeszutek Wilk Cc: Minchan Kim Cc: Stefan Hengelein Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/frontswap.c | 57 ++++++++++++++++++++++++++++++--------------------------- 1 file changed, 30 insertions(+), 27 deletions(-) (limited to 'mm') diff --git a/mm/frontswap.c b/mm/frontswap.c index e44c9cbd144..2760b0f9882 100644 --- a/mm/frontswap.c +++ b/mm/frontswap.c @@ -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) +{ + 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; } -- cgit v1.2.3