Messages in this thread Patch in this message | | | Date | Tue, 26 May 2009 12:14:12 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | [RFC][PATCH 1/5] change swap cache interfaces |
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From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
In following patch, usage of swap cache will be recorded into swap_map. This patch is for necessary interface changes to do that.
2 interfaces: - swapcache_prepare() - swapcache_free() is added for allocating/freeing refcnt from swap-cache to existing swap entries. But implementation itself is not changed under this patch. At adding swapcache_free(), memcg's hook code is moved under swapcache_free(). This is better than using scattered hooks.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> --- include/linux/swap.h | 7 +++++++ mm/swap_state.c | 11 +++++------ mm/swapfile.c | 19 +++++++++++++++++++ mm/vmscan.c | 3 +-- 4 files changed, 32 insertions(+), 8 deletions(-)
Index: new-trial-swapcount/include/linux/swap.h =================================================================== --- new-trial-swapcount.orig/include/linux/swap.h +++ new-trial-swapcount/include/linux/swap.h @@ -301,8 +301,10 @@ extern void si_swapinfo(struct sysinfo * extern swp_entry_t get_swap_page(void); extern swp_entry_t get_swap_page_of_type(int); extern int swap_duplicate(swp_entry_t); +extern int swapcache_prepare(swp_entry_t); extern int valid_swaphandles(swp_entry_t, unsigned long *); extern void swap_free(swp_entry_t); +extern void swapcache_free(swp_entry_t, struct page *page); extern int free_swap_and_cache(swp_entry_t); extern int swap_type_of(dev_t, sector_t, struct block_device **); extern unsigned int count_swap_pages(int, int); @@ -371,11 +373,16 @@ static inline void show_swap_cache_info( #define free_swap_and_cache(swp) is_migration_entry(swp) #define swap_duplicate(swp) is_migration_entry(swp) +#define swapcache_prepare(swp) is_migration_entry(swp) static inline void swap_free(swp_entry_t swp) { } +static inline void swapcache_free(swp_entry_t swp, struct page *page) +{ +} + static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask, struct vm_area_struct *vma, unsigned long addr) { Index: new-trial-swapcount/mm/swap_state.c =================================================================== --- new-trial-swapcount.orig/mm/swap_state.c +++ new-trial-swapcount/mm/swap_state.c @@ -162,11 +162,11 @@ int add_to_swap(struct page *page) return 1; case -EEXIST: /* Raced with "speculative" read_swap_cache_async */ - swap_free(entry); + swapcache_free(entry, NULL); continue; default: /* -ENOMEM radix-tree allocation failure */ - swap_free(entry); + swapcache_free(entry, NULL); return 0; } } @@ -188,8 +188,7 @@ void delete_from_swap_cache(struct page __delete_from_swap_cache(page); spin_unlock_irq(&swapper_space.tree_lock); - mem_cgroup_uncharge_swapcache(page, entry); - swap_free(entry); + swapcache_free(entry, page); page_cache_release(page); } @@ -293,7 +292,7 @@ struct page *read_swap_cache_async(swp_e /* * Swap entry may have been freed since our caller observed it. */ - if (!swap_duplicate(entry)) + if (!swapcache_prepare(entry)) break; /* @@ -317,7 +316,7 @@ struct page *read_swap_cache_async(swp_e } ClearPageSwapBacked(new_page); __clear_page_locked(new_page); - swap_free(entry); + swapcache_free(entry, NULL); } while (err != -ENOMEM); if (new_page) Index: new-trial-swapcount/mm/swapfile.c =================================================================== --- new-trial-swapcount.orig/mm/swapfile.c +++ new-trial-swapcount/mm/swapfile.c @@ -510,6 +510,16 @@ void swap_free(swp_entry_t entry) } /* + * Called after dropping swapcache to decrease refcnt to swap entries. + */ +void swapcache_free(swp_entry_t entry, struct page *page) +{ + if (page) + mem_cgroup_uncharge_swapcache(page, entry); + return swap_free(entry); +} + +/* * How many references to page are currently swapped out? */ static inline int page_swapcount(struct page *page) @@ -1979,6 +1989,15 @@ bad_file: goto out; } +/* + * Called when allocating swap cache for exising swap entry, + */ +int swapcache_prepare(swp_entry_t entry) +{ + return swap_duplicate(entry); +} + + struct swap_info_struct * get_swap_info_struct(unsigned type) { Index: new-trial-swapcount/mm/vmscan.c =================================================================== --- new-trial-swapcount.orig/mm/vmscan.c +++ new-trial-swapcount/mm/vmscan.c @@ -477,8 +477,7 @@ static int __remove_mapping(struct addre swp_entry_t swap = { .val = page_private(page) }; __delete_from_swap_cache(page); spin_unlock_irq(&mapping->tree_lock); - mem_cgroup_uncharge_swapcache(page, swap); - swap_free(swap); + swapcache_free(swap, page); } else { __remove_from_page_cache(page); spin_unlock_irq(&mapping->tree_lock);
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