From 73b1262fa43a778b1e154deea632cdef5009d6a1 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 4 Feb 2008 22:28:50 -0800 Subject: [PATCH] tmpfs: move swap swizzling into shmem move_to_swap_cache and move_from_swap_cache functions (which swizzle a page between tmpfs page cache and swap cache, to avoid page copying) are only used by shmem.c; and our subsequent fix for unionfs needs different treatments in the two instances of move_from_swap_cache. Move them from swap_state.c into their callsites shmem_writepage, shmem_unuse_inode and shmem_getpage, making add_to_swap_cache externally visible. shmem.c likes to say set_page_dirty where swap_state.c liked to say SetPageDirty: respect that diversity, which __set_page_dirty_no_writeback makes moot (and implies we should lose that "shift page from clean_pages to dirty_pages list" comment: it's on neither). Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/swap.h | 15 ++++----------- mm/shmem.c | 16 ++++++++++++---- mm/swap_state.c | 35 +---------------------------------- 3 files changed, 17 insertions(+), 49 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index 16fd1209e9f..353153ea0bd 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -220,11 +220,9 @@ extern struct address_space swapper_space; #define total_swapcache_pages swapper_space.nrpages extern void show_swap_cache_info(void); extern int add_to_swap(struct page *, gfp_t); +extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t); extern void __delete_from_swap_cache(struct page *); extern void delete_from_swap_cache(struct page *); -extern int move_to_swap_cache(struct page *, swp_entry_t); -extern int move_from_swap_cache(struct page *, unsigned long, - struct address_space *); extern void free_page_and_swap_cache(struct page *); extern void free_pages_and_swap_cache(struct page **, int); extern struct page *lookup_swap_cache(swp_entry_t); @@ -319,15 +317,10 @@ static inline struct page *lookup_swap_cache(swp_entry_t swp) #define can_share_swap_page(p) (page_mapcount(p) == 1) -static inline int move_to_swap_cache(struct page *page, swp_entry_t entry) +static inline int add_to_swap_cache(struct page *page, swp_entry_t entry, + gfp_t gfp_mask) { - return 1; -} - -static inline int move_from_swap_cache(struct page *page, unsigned long index, - struct address_space *mapping) -{ - return 1; + return -1; } static inline void __delete_from_swap_cache(struct page *page) diff --git a/mm/shmem.c b/mm/shmem.c index 7be94342bf0..e577adf4ae8 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -884,7 +884,9 @@ lost2: found: idx += offset; inode = &info->vfs_inode; - if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) { + if (add_to_page_cache(page, inode->i_mapping, idx, GFP_ATOMIC) == 0) { + delete_from_swap_cache(page); + set_page_dirty(page); info->flags |= SHMEM_PAGEIN; shmem_swp_set(info, ptr + offset, 0); } @@ -972,7 +974,8 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) BUG_ON(!entry); BUG_ON(entry->val); - if (move_to_swap_cache(page, swap) == 0) { + if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { + remove_from_page_cache(page); shmem_swp_set(info, entry, swap.val); shmem_swp_unmap(entry); spin_unlock(&info->lock); @@ -982,6 +985,9 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) list_move_tail(&info->swaplist, &shmem_swaplist); spin_unlock(&shmem_swaplist_lock); } + swap_duplicate(swap); + page_cache_release(page); /* pagecache ref */ + set_page_dirty(page); unlock_page(page); return 0; } @@ -1217,13 +1223,15 @@ repeat: SetPageUptodate(filepage); set_page_dirty(filepage); swap_free(swap); - } else if (!(error = move_from_swap_cache( - swappage, idx, mapping))) { + } else if (!(error = add_to_page_cache( + swappage, mapping, idx, GFP_ATOMIC))) { info->flags |= SHMEM_PAGEIN; shmem_swp_set(info, entry, 0); shmem_swp_unmap(entry); + delete_from_swap_cache(swappage); spin_unlock(&info->lock); filepage = swappage; + set_page_dirty(filepage); swap_free(swap); } else { shmem_swp_unmap(entry); diff --git a/mm/swap_state.c b/mm/swap_state.c index c75eda2c9cc..65b81c92738 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -67,8 +67,7 @@ void show_swap_cache_info(void) * add_to_swap_cache resembles add_to_page_cache on swapper_space, * but sets SwapCache flag and private instead of mapping and index. */ -static int add_to_swap_cache(struct page *page, swp_entry_t entry, - gfp_t gfp_mask) +int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask) { int error; @@ -183,38 +182,6 @@ void delete_from_swap_cache(struct page *page) page_cache_release(page); } -/* - * Strange swizzling function only for use by shmem_writepage - */ -int move_to_swap_cache(struct page *page, swp_entry_t entry) -{ - int err = add_to_swap_cache(page, entry, GFP_ATOMIC); - if (!err) { - remove_from_page_cache(page); - page_cache_release(page); /* pagecache ref */ - if (!swap_duplicate(entry)) - BUG(); - SetPageDirty(page); - } - return err; -} - -/* - * Strange swizzling function for shmem_getpage (and shmem_unuse) - */ -int move_from_swap_cache(struct page *page, unsigned long index, - struct address_space *mapping) -{ - int err = add_to_page_cache(page, mapping, index, GFP_ATOMIC); - if (!err) { - delete_from_swap_cache(page); - /* shift page from clean_pages to dirty_pages list */ - ClearPageDirty(page); - set_page_dirty(page); - } - return err; -} - /* * If we are the only user, then try to free up the swap cache. * -- 2.41.1