312 lines
11 KiB
C
312 lines
11 KiB
C
/*
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* Macros for manipulating and testing page->flags
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*/
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#ifndef PAGE_FLAGS_H
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#define PAGE_FLAGS_H
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#include <linux/types.h>
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#include <linux/mm_types.h>
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/*
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* Various page->flags bits:
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*
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* PG_reserved is set for special pages, which can never be swapped out. Some
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* of them might not even exist (eg empty_bad_page)...
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*
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* The PG_private bitflag is set on pagecache pages if they contain filesystem
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* specific data (which is normally at page->private). It can be used by
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* private allocations for its own usage.
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*
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* During initiation of disk I/O, PG_locked is set. This bit is set before I/O
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* and cleared when writeback _starts_ or when read _completes_. PG_writeback
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* is set before writeback starts and cleared when it finishes.
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*
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* PG_locked also pins a page in pagecache, and blocks truncation of the file
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* while it is held.
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*
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* page_waitqueue(page) is a wait queue of all tasks waiting for the page
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* to become unlocked.
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*
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* PG_uptodate tells whether the page's contents is valid. When a read
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* completes, the page becomes uptodate, unless a disk I/O error happened.
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*
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* PG_referenced, PG_reclaim are used for page reclaim for anonymous and
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* file-backed pagecache (see mm/vmscan.c).
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*
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* PG_error is set to indicate that an I/O error occurred on this page.
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*
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* PG_arch_1 is an architecture specific page state bit. The generic code
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* guarantees that this bit is cleared for a page when it first is entered into
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* the page cache.
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*
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* PG_highmem pages are not permanently mapped into the kernel virtual address
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* space, they need to be kmapped separately for doing IO on the pages. The
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* struct page (these bits with information) are always mapped into kernel
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* address space...
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*
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* PG_buddy is set to indicate that the page is free and in the buddy system
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* (see mm/page_alloc.c).
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*
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*/
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/*
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* Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
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* locked- and dirty-page accounting.
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*
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* The page flags field is split into two parts, the main flags area
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* which extends from the low bits upwards, and the fields area which
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* extends from the high bits downwards.
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*
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* | FIELD | ... | FLAGS |
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* N-1 ^ 0
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* (N-FLAGS_RESERVED)
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*
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* The fields area is reserved for fields mapping zone, node and SPARSEMEM
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* section. The boundry between these two areas is defined by
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* FLAGS_RESERVED which defines the width of the fields section
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* (see linux/mmzone.h). New flags must _not_ overlap with this area.
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*/
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#define PG_locked 0 /* Page is locked. Don't touch. */
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#define PG_error 1
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#define PG_referenced 2
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#define PG_uptodate 3
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#define PG_dirty 4
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#define PG_lru 5
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#define PG_active 6
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#define PG_slab 7 /* slab debug (Suparna wants this) */
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#define PG_owner_priv_1 8 /* Owner use. If pagecache, fs may use*/
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#define PG_arch_1 9
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#define PG_reserved 10
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#define PG_private 11 /* If pagecache, has fs-private data */
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#define PG_writeback 12 /* Page is under writeback */
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#define PG_compound 14 /* Part of a compound page */
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#define PG_swapcache 15 /* Swap page: swp_entry_t in private */
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#define PG_mappedtodisk 16 /* Has blocks allocated on-disk */
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#define PG_reclaim 17 /* To be reclaimed asap */
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#define PG_buddy 19 /* Page is free, on buddy lists */
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/* PG_readahead is only used for file reads; PG_reclaim is only for writes */
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#define PG_readahead PG_reclaim /* Reminder to do async read-ahead */
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/* PG_owner_priv_1 users should have descriptive aliases */
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#define PG_checked PG_owner_priv_1 /* Used by some filesystems */
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#define PG_pinned PG_owner_priv_1 /* Xen pinned pagetable */
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#if (BITS_PER_LONG > 32)
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/*
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* 64-bit-only flags build down from bit 31
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*
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* 32 bit -------------------------------| FIELDS | FLAGS |
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* 64 bit | FIELDS | ?????? FLAGS |
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* 63 32 0
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*/
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#define PG_uncached 31 /* Page has been mapped as uncached */
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#endif
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/*
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* Manipulation of page state flags
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*/
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#define PageLocked(page) \
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test_bit(PG_locked, &(page)->flags)
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#define SetPageLocked(page) \
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set_bit(PG_locked, &(page)->flags)
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#define TestSetPageLocked(page) \
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test_and_set_bit(PG_locked, &(page)->flags)
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#define ClearPageLocked(page) \
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clear_bit(PG_locked, &(page)->flags)
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#define TestClearPageLocked(page) \
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test_and_clear_bit(PG_locked, &(page)->flags)
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#define PageError(page) test_bit(PG_error, &(page)->flags)
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#define SetPageError(page) set_bit(PG_error, &(page)->flags)
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#define ClearPageError(page) clear_bit(PG_error, &(page)->flags)
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#define PageReferenced(page) test_bit(PG_referenced, &(page)->flags)
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#define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags)
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#define ClearPageReferenced(page) clear_bit(PG_referenced, &(page)->flags)
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#define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
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static inline int PageUptodate(struct page *page)
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{
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int ret = test_bit(PG_uptodate, &(page)->flags);
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/*
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* Must ensure that the data we read out of the page is loaded
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* _after_ we've loaded page->flags to check for PageUptodate.
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* We can skip the barrier if the page is not uptodate, because
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* we wouldn't be reading anything from it.
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*
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* See SetPageUptodate() for the other side of the story.
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*/
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if (ret)
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smp_rmb();
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return ret;
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}
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static inline void __SetPageUptodate(struct page *page)
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{
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smp_wmb();
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__set_bit(PG_uptodate, &(page)->flags);
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#ifdef CONFIG_S390
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page_clear_dirty(page);
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#endif
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}
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static inline void SetPageUptodate(struct page *page)
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{
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#ifdef CONFIG_S390
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if (!test_and_set_bit(PG_uptodate, &page->flags))
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page_clear_dirty(page);
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#else
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/*
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* Memory barrier must be issued before setting the PG_uptodate bit,
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* so that all previous stores issued in order to bring the page
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* uptodate are actually visible before PageUptodate becomes true.
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*
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* s390 doesn't need an explicit smp_wmb here because the test and
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* set bit already provides full barriers.
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*/
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smp_wmb();
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set_bit(PG_uptodate, &(page)->flags);
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#endif
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}
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#define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
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#define PageDirty(page) test_bit(PG_dirty, &(page)->flags)
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#define SetPageDirty(page) set_bit(PG_dirty, &(page)->flags)
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#define TestSetPageDirty(page) test_and_set_bit(PG_dirty, &(page)->flags)
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#define ClearPageDirty(page) clear_bit(PG_dirty, &(page)->flags)
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#define __ClearPageDirty(page) __clear_bit(PG_dirty, &(page)->flags)
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#define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
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#define PageLRU(page) test_bit(PG_lru, &(page)->flags)
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#define SetPageLRU(page) set_bit(PG_lru, &(page)->flags)
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#define ClearPageLRU(page) clear_bit(PG_lru, &(page)->flags)
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#define __ClearPageLRU(page) __clear_bit(PG_lru, &(page)->flags)
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#define PageActive(page) test_bit(PG_active, &(page)->flags)
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#define SetPageActive(page) set_bit(PG_active, &(page)->flags)
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#define ClearPageActive(page) clear_bit(PG_active, &(page)->flags)
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#define __ClearPageActive(page) __clear_bit(PG_active, &(page)->flags)
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#define PageSlab(page) test_bit(PG_slab, &(page)->flags)
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#define __SetPageSlab(page) __set_bit(PG_slab, &(page)->flags)
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#define __ClearPageSlab(page) __clear_bit(PG_slab, &(page)->flags)
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#ifdef CONFIG_HIGHMEM
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#define PageHighMem(page) is_highmem(page_zone(page))
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#else
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#define PageHighMem(page) 0 /* needed to optimize away at compile time */
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#endif
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#define PageChecked(page) test_bit(PG_checked, &(page)->flags)
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#define SetPageChecked(page) set_bit(PG_checked, &(page)->flags)
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#define ClearPageChecked(page) clear_bit(PG_checked, &(page)->flags)
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#define PagePinned(page) test_bit(PG_pinned, &(page)->flags)
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#define SetPagePinned(page) set_bit(PG_pinned, &(page)->flags)
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#define ClearPagePinned(page) clear_bit(PG_pinned, &(page)->flags)
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#define PageReserved(page) test_bit(PG_reserved, &(page)->flags)
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#define SetPageReserved(page) set_bit(PG_reserved, &(page)->flags)
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#define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
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#define __ClearPageReserved(page) __clear_bit(PG_reserved, &(page)->flags)
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#define SetPagePrivate(page) set_bit(PG_private, &(page)->flags)
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#define ClearPagePrivate(page) clear_bit(PG_private, &(page)->flags)
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#define PagePrivate(page) test_bit(PG_private, &(page)->flags)
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#define __SetPagePrivate(page) __set_bit(PG_private, &(page)->flags)
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#define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
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/*
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* Only test-and-set exist for PG_writeback. The unconditional operators are
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* risky: they bypass page accounting.
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*/
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#define PageWriteback(page) test_bit(PG_writeback, &(page)->flags)
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#define TestSetPageWriteback(page) test_and_set_bit(PG_writeback, \
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&(page)->flags)
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#define TestClearPageWriteback(page) test_and_clear_bit(PG_writeback, \
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&(page)->flags)
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#define PageBuddy(page) test_bit(PG_buddy, &(page)->flags)
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#define __SetPageBuddy(page) __set_bit(PG_buddy, &(page)->flags)
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#define __ClearPageBuddy(page) __clear_bit(PG_buddy, &(page)->flags)
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#define PageMappedToDisk(page) test_bit(PG_mappedtodisk, &(page)->flags)
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#define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
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#define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
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#define PageReadahead(page) test_bit(PG_readahead, &(page)->flags)
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#define SetPageReadahead(page) set_bit(PG_readahead, &(page)->flags)
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#define ClearPageReadahead(page) clear_bit(PG_readahead, &(page)->flags)
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#define PageReclaim(page) test_bit(PG_reclaim, &(page)->flags)
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#define SetPageReclaim(page) set_bit(PG_reclaim, &(page)->flags)
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#define ClearPageReclaim(page) clear_bit(PG_reclaim, &(page)->flags)
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#define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)
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#define PageCompound(page) test_bit(PG_compound, &(page)->flags)
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#define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags)
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#define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags)
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/*
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* PG_reclaim is used in combination with PG_compound to mark the
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* head and tail of a compound page
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*
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* PG_compound & PG_reclaim => Tail page
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* PG_compound & ~PG_reclaim => Head page
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*/
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#define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
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#define PageTail(page) (((page)->flags & PG_head_tail_mask) \
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== PG_head_tail_mask)
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static inline void __SetPageTail(struct page *page)
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{
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page->flags |= PG_head_tail_mask;
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}
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static inline void __ClearPageTail(struct page *page)
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{
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page->flags &= ~PG_head_tail_mask;
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}
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#define PageHead(page) (((page)->flags & PG_head_tail_mask) \
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== (1L << PG_compound))
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#define __SetPageHead(page) __SetPageCompound(page)
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#define __ClearPageHead(page) __ClearPageCompound(page)
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#ifdef CONFIG_SWAP
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#define PageSwapCache(page) test_bit(PG_swapcache, &(page)->flags)
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#define SetPageSwapCache(page) set_bit(PG_swapcache, &(page)->flags)
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#define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags)
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#else
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#define PageSwapCache(page) 0
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#endif
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#define PageUncached(page) test_bit(PG_uncached, &(page)->flags)
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#define SetPageUncached(page) set_bit(PG_uncached, &(page)->flags)
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#define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags)
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struct page; /* forward declaration */
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extern void cancel_dirty_page(struct page *page, unsigned int account_size);
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int test_clear_page_writeback(struct page *page);
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int test_set_page_writeback(struct page *page);
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static inline void set_page_writeback(struct page *page)
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{
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test_set_page_writeback(page);
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}
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#endif /* PAGE_FLAGS_H */
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