From cb4b86ba47bb0937b71fb825b3ed88adf7a190f0 Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Tue, 16 Jun 2009 15:32:52 -0700 Subject: [PATCH] mm: add swap cache interface for swap reference In a following patch, the usage of swap cache is recorded into swap_map. This patch is for necessary interface changes to do that. 2 interfaces: - swapcache_prepare() - swapcache_free() are 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 Reviewed-by: Daisuke Nishimura Acked-by: Balbir Singh Cc: Hugh Dickins Cc: Johannes Weiner Cc: Li Zefan Cc: Dhaval Giani Cc: YAMAMOTO Takashi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/swap.h | 7 +++++++ mm/shmem.c | 2 +- mm/swap_state.c | 11 +++++------ mm/swapfile.c | 19 +++++++++++++++++++ mm/vmscan.c | 3 +-- 5 files changed, 33 insertions(+), 9 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index f30c06908f0..259e96c150e 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -282,8 +282,10 @@ 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); @@ -352,11 +354,16 @@ static inline void show_swap_cache_info(void) #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) { diff --git a/mm/shmem.c b/mm/shmem.c index 0132fbd45a2..47ab1918228 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1097,7 +1097,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) shmem_swp_unmap(entry); unlock: spin_unlock(&info->lock); - swap_free(swap); + swapcache_free(swap, NULL); redirty: set_page_dirty(page); if (wbc->for_reclaim) diff --git a/mm/swap_state.c b/mm/swap_state.c index 1416e7e9e02..19bdf3017a9 100644 --- a/mm/swap_state.c +++ b/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 *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_entry_t entry, gfp_t gfp_mask, /* * 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_entry_t entry, gfp_t gfp_mask, } ClearPageSwapBacked(new_page); __clear_page_locked(new_page); - swap_free(entry); + swapcache_free(entry, NULL); } while (err != -ENOMEM); if (new_page) diff --git a/mm/swapfile.c b/mm/swapfile.c index 312fafe0ab6..3187079903f 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -509,6 +509,16 @@ 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? */ @@ -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) { diff --git a/mm/vmscan.c b/mm/vmscan.c index 2c4b945b011..52339dd7bf8 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -470,8 +470,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page) 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); -- 2.20.1