Recruit a couple of page flags to aid in cache management. The following extra flags are defined: (1) PG_fscache (PG_owner_priv_2) The marked page is backed by a local cache and is pinning resources in the cache driver. (2) PG_fscache_write (PG_owner_priv_3) The marked page is being written to the local cache. The page may not be modified whilst this is in progress. If PG_fscache is set, then things that checked for PG_private will now also check for that. This includes things like truncation and page invalidation. The function page_has_private() had been added to detect this. Signed-off-by: David Howells <dhowells@xxxxxxxxxx> --- fs/splice.c | 2 +- include/linux/page-flags.h | 30 +++++++++++++++++++++++++++++- include/linux/pagemap.h | 11 +++++++++++ mm/filemap.c | 16 ++++++++++++++++ mm/migrate.c | 2 +- mm/page_alloc.c | 3 +++ mm/readahead.c | 9 +++++---- mm/swap.c | 4 ++-- mm/swap_state.c | 4 ++-- mm/truncate.c | 10 +++++----- mm/vmscan.c | 2 +- 11 files changed, 76 insertions(+), 17 deletions(-) diff --git a/fs/splice.c b/fs/splice.c index c010a72..ae4f5b7 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -58,7 +58,7 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, */ wait_on_page_writeback(page); - if (PagePrivate(page)) + if (page_has_private(page)) try_to_release_page(page, GFP_KERNEL); /* diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 209d3a4..eaf9854 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -83,19 +83,24 @@ #define PG_private 11 /* If pagecache, has fs-private data */ #define PG_writeback 12 /* Page is under writeback */ +#define PG_owner_priv_2 13 /* Owner use. If pagecache, fs may use */ #define PG_compound 14 /* Part of a compound page */ #define PG_swapcache 15 /* Swap page: swp_entry_t in private */ #define PG_mappedtodisk 16 /* Has blocks allocated on-disk */ #define PG_reclaim 17 /* To be reclaimed asap */ +#define PG_owner_priv_3 18 /* Owner use. If pagecache, fs may use */ #define PG_buddy 19 /* Page is free, on buddy lists */ /* PG_readahead is only used for file reads; PG_reclaim is only for writes */ #define PG_readahead PG_reclaim /* Reminder to do async read-ahead */ -/* PG_owner_priv_1 users should have descriptive aliases */ +/* PG_owner_priv_1/2/3 users should have descriptive aliases */ #define PG_checked PG_owner_priv_1 /* Used by some filesystems */ #define PG_pinned PG_owner_priv_1 /* Xen pinned pagetable */ +#define PG_fscache PG_owner_priv_2 /* Backed by local cache */ +#define PG_fscache_write PG_owner_priv_3 /* Writing to local cache */ + #if (BITS_PER_LONG > 32) /* @@ -199,6 +204,18 @@ static inline void SetPageUptodate(struct page *page) #define TestClearPageWriteback(page) test_and_clear_bit(PG_writeback, \ &(page)->flags) +#define PageFsCache(page) test_bit(PG_fscache, &(page)->flags) +#define SetPageFsCache(page) set_bit(PG_fscache, &(page)->flags) +#define ClearPageFsCache(page) clear_bit(PG_fscache, &(page)->flags) +#define TestSetPageFsCache(page) test_and_set_bit(PG_fscache, &(page)->flags) +#define TestClearPageFsCache(page) test_and_clear_bit(PG_fscache, &(page)->flags) + +#define PageFsCacheWrite(page) test_bit(PG_fscache_write, &(page)->flags) +#define SetPageFsCacheWrite(page) set_bit(PG_fscache_write, &(page)->flags) +#define ClearPageFsCacheWrite(page) clear_bit(PG_fscache_write, &(page)->flags) +#define TestSetPageFsCacheWrite(page) test_and_set_bit(PG_fscache_write, &(page)->flags) +#define TestClearPageFsCacheWrite(page) test_and_clear_bit(PG_fscache_write, &(page)->flags) + #define PageBuddy(page) test_bit(PG_buddy, &(page)->flags) #define __SetPageBuddy(page) __set_bit(PG_buddy, &(page)->flags) #define __ClearPageBuddy(page) __clear_bit(PG_buddy, &(page)->flags) @@ -272,4 +289,15 @@ static inline void set_page_writeback(struct page *page) test_set_page_writeback(page); } +/** + * page_has_private - Determine if page has private stuff + * @page: The page to be checked + * + * Determine if a page has private stuff, indicating that release routines + * should be invoked upon it. + */ +#define page_has_private(page) \ + ((page)->flags & ((1 << PG_private) | \ + (1 << PG_fscache))) + #endif /* PAGE_FLAGS_H */ diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 8a83537..d1049b6 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -208,6 +208,17 @@ static inline void wait_on_page_writeback(struct page *page) extern void end_page_writeback(struct page *page); +/* + * Wait for a page to finish being written to a local cache + */ +static inline void wait_on_page_fscache_write(struct page *page) +{ + if (PageFsCacheWrite(page)) + wait_on_page_bit(page, PG_fscache_write); +} + +extern void end_page_fscache_write(struct page *page); + /* * Fault a userspace page into pagetables. Return non-zero on a fault. * diff --git a/mm/filemap.c b/mm/filemap.c index 6cf700d..7b96487 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -557,6 +557,19 @@ void end_page_writeback(struct page *page) EXPORT_SYMBOL(end_page_writeback); /** + * end_page_fscache_write - End writing page to cache + * @page: the page + */ +void end_page_fscache_write(struct page *page) +{ + if (!TestClearPageFsCacheWrite(page)) + BUG(); + smp_mb__after_clear_bit(); + wake_up_page(page, PG_fscache_write); +} +EXPORT_SYMBOL(end_page_fscache_write); + +/** * __lock_page - get a lock on the page, assuming we need to sleep to get it * @page: the page to lock * @@ -2243,6 +2256,9 @@ out: * (presumably at page->private). If the release was successful, return `1'. * Otherwise return zero. * + * This may also be called if PG_fscache is set on a page, indicating that the + * page is known to the local caching routines. + * * The @gfp_mask argument specifies whether I/O may be performed to release * this page (__GFP_IO), and whether the call may block (__GFP_WAIT). * diff --git a/mm/migrate.c b/mm/migrate.c index 37c73b9..828cacf 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -544,7 +544,7 @@ static int fallback_migrate_page(struct address_space *mapping, * Buffers may be managed in a filesystem specific way. * We must have no buffers or drop them. */ - if (PagePrivate(page) && + if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL)) return -EAGAIN; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 3da85b8..96a42d1 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -208,6 +208,7 @@ static void bad_page(struct page *page) dump_stack(); page->flags &= ~(1 << PG_lru | 1 << PG_private | + 1 << PG_fscache | 1 << PG_locked | 1 << PG_active | 1 << PG_dirty | @@ -445,6 +446,7 @@ static inline int free_pages_check(struct page *page) (page->flags & ( 1 << PG_lru | 1 << PG_private | + 1 << PG_fscache | 1 << PG_locked | 1 << PG_active | 1 << PG_slab | @@ -593,6 +595,7 @@ static int prep_new_page(struct page *page, int order, gfp_t gfp_flags) (page->flags & ( 1 << PG_lru | 1 << PG_private | + 1 << PG_fscache | 1 << PG_locked | 1 << PG_active | 1 << PG_dirty | diff --git a/mm/readahead.c b/mm/readahead.c index 12d1378..8b5e017 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -54,14 +54,15 @@ EXPORT_SYMBOL_GPL(file_ra_state_init); /* * see if a page needs releasing upon read_cache_pages() failure - * - the caller of read_cache_pages() may have set PG_private before calling, - * such as the NFS fs marking pages that are cached locally on disk, thus we - * need to give the fs a chance to clean up in the event of an error + * - the caller of read_cache_pages() may have set PG_private or PG_fscache + * before calling, such as the NFS fs marking pages that are cached locally + * on disk, thus we need to give the fs a chance to clean up in the event of + * an error */ static void read_cache_pages_invalidate_page(struct address_space *mapping, struct page *page) { - if (PagePrivate(page)) { + if (page_has_private(page)) { if (TestSetPageLocked(page)) BUG(); page->mapping = mapping; diff --git a/mm/swap.c b/mm/swap.c index d3cb966..498d0c1 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -412,8 +412,8 @@ void pagevec_strip(struct pagevec *pvec) for (i = 0; i < pagevec_count(pvec); i++) { struct page *page = pvec->pages[i]; - if (PagePrivate(page) && !TestSetPageLocked(page)) { - if (PagePrivate(page)) + if (page_has_private(page) && !TestSetPageLocked(page)) { + if (page_has_private(page)) try_to_release_page(page, 0); unlock_page(page); } diff --git a/mm/swap_state.c b/mm/swap_state.c index 67daecb..93667ef 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -75,7 +75,7 @@ static int __add_to_swap_cache(struct page *page, swp_entry_t entry, int error; BUG_ON(PageSwapCache(page)); - BUG_ON(PagePrivate(page)); + BUG_ON(page_has_private(page)); error = radix_tree_preload(gfp_mask); if (!error) { write_lock_irq(&swapper_space.tree_lock); @@ -126,7 +126,7 @@ void __delete_from_swap_cache(struct page *page) BUG_ON(!PageLocked(page)); BUG_ON(!PageSwapCache(page)); BUG_ON(PageWriteback(page)); - BUG_ON(PagePrivate(page)); + BUG_ON(page_has_private(page)); radix_tree_delete(&swapper_space.page_tree, page_private(page)); set_page_private(page, 0); diff --git a/mm/truncate.c b/mm/truncate.c index 5cdfbc1..5555cb0 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -48,7 +48,7 @@ void do_invalidatepage(struct page *page, unsigned long offset) static inline void truncate_partial_page(struct page *page, unsigned partial) { zero_user_page(page, partial, PAGE_CACHE_SIZE - partial, KM_USER0); - if (PagePrivate(page)) + if (page_has_private(page)) do_invalidatepage(page, partial); } @@ -97,7 +97,7 @@ truncate_complete_page(struct address_space *mapping, struct page *page) cancel_dirty_page(page, PAGE_CACHE_SIZE); - if (PagePrivate(page)) + if (page_has_private(page)) do_invalidatepage(page, 0); remove_from_page_cache(page); @@ -122,7 +122,7 @@ invalidate_complete_page(struct address_space *mapping, struct page *page) if (page->mapping != mapping) return 0; - if (PagePrivate(page) && !try_to_release_page(page, 0)) + if (page_has_private(page) && !try_to_release_page(page, 0)) return 0; ret = remove_mapping(mapping, page); @@ -344,14 +344,14 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page) if (page->mapping != mapping) return 0; - if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL)) + if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL)) return 0; write_lock_irq(&mapping->tree_lock); if (PageDirty(page)) goto failed; - BUG_ON(PagePrivate(page)); + BUG_ON(page_has_private(page)); __remove_from_page_cache(page); write_unlock_irq(&mapping->tree_lock); ClearPageUptodate(page); diff --git a/mm/vmscan.c b/mm/vmscan.c index d419e10..de851f4 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -548,7 +548,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, * process address space (page_count == 1) it can be freed. * Otherwise, leave the page on the LRU so it is swappable. */ - if (PagePrivate(page)) { + if (page_has_private(page)) { if (!try_to_release_page(page, sc->gfp_mask)) goto activate_locked; if (!mapping && page_count(page) == 1) - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html