#define PAGE_FLAGS_H
#include <linux/types.h>
+#include <linux/mm_types.h>
/*
* Various page->flags bits:
* PG_reserved is set for special pages, which can never be swapped out. Some
* of them might not even exist (eg empty_bad_page)...
*
- * The PG_private bitflag is set if page->private contains a valid value.
+ * The PG_private bitflag is set on pagecache pages if they contain filesystem
+ * specific data (which is normally at page->private). It can be used by
+ * private allocations for its own usage.
*
- * During disk I/O, PG_locked is used. This bit is set before I/O and
- * reset when I/O completes. page_waitqueue(page) is a wait queue of all tasks
- * waiting for the I/O on this page to complete.
+ * During initiation of disk I/O, PG_locked is set. This bit is set before I/O
+ * and cleared when writeback _starts_ or when read _completes_. PG_writeback
+ * is set before writeback starts and cleared when it finishes.
+ *
+ * PG_locked also pins a page in pagecache, and blocks truncation of the file
+ * while it is held.
+ *
+ * page_waitqueue(page) is a wait queue of all tasks waiting for the page
+ * to become unlocked.
*
* PG_uptodate tells whether the page's contents is valid. When a read
* completes, the page becomes uptodate, unless a disk I/O error happened.
*
- * For choosing which pages to swap out, inode pages carry a PG_referenced bit,
- * which is set any time the system accesses that page through the (mapping,
- * index) hash table. This referenced bit, together with the referenced bit
- * in the page tables, is used to manipulate page->age and move the page across
- * the active, inactive_dirty and inactive_clean lists.
- *
- * Note that the referenced bit, the page->lru list_head and the active,
- * inactive_dirty and inactive_clean lists are protected by the
- * zone->lru_lock, and *NOT* by the usual PG_locked bit!
+ * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
+ * file-backed pagecache (see mm/vmscan.c).
*
* PG_error is set to indicate that an I/O error occurred on this page.
*
* space, they need to be kmapped separately for doing IO on the pages. The
* struct page (these bits with information) are always mapped into kernel
* address space...
+ *
+ * PG_buddy is set to indicate that the page is free and in the buddy system
+ * (see mm/page_alloc.c).
+ *
*/
/*
#define PG_active 6
#define PG_slab 7 /* slab debug (Suparna wants this) */
-#define PG_checked 8 /* kill me in 2.5.<early>. */
+#define PG_owner_priv_1 8 /* Owner use. If pagecache, fs may use*/
#define PG_arch_1 9
#define PG_reserved 10
-#define PG_private 11 /* Has something at ->private */
+#define PG_private 11 /* If pagecache, has fs-private data */
#define PG_writeback 12 /* Page is under writeback */
-#define PG_nosave 13 /* Used for system suspend/resume */
#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_nosave_free 18 /* Free, should not be written */
#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 */
+#define PG_checked PG_owner_priv_1 /* Used by some filesystems */
+#define PG_pinned PG_owner_priv_1 /* Xen pinned pagetable */
#if (BITS_PER_LONG > 32)
/*
#define PageUptodate(page) test_bit(PG_uptodate, &(page)->flags)
#ifdef CONFIG_S390
-#define SetPageUptodate(_page) \
- do { \
- struct page *__page = (_page); \
- if (!test_and_set_bit(PG_uptodate, &__page->flags)) \
- page_test_and_clear_dirty(_page); \
- } while (0)
+static inline void SetPageUptodate(struct page *page)
+{
+ if (!test_and_set_bit(PG_uptodate, &page->flags))
+ page_clear_dirty(page);
+}
#else
#define SetPageUptodate(page) set_bit(PG_uptodate, &(page)->flags)
#endif
#define SetPageChecked(page) set_bit(PG_checked, &(page)->flags)
#define ClearPageChecked(page) clear_bit(PG_checked, &(page)->flags)
+#define PagePinned(page) test_bit(PG_pinned, &(page)->flags)
+#define SetPagePinned(page) set_bit(PG_pinned, &(page)->flags)
+#define ClearPagePinned(page) clear_bit(PG_pinned, &(page)->flags)
+
#define PageReserved(page) test_bit(PG_reserved, &(page)->flags)
#define SetPageReserved(page) set_bit(PG_reserved, &(page)->flags)
#define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
#define __SetPagePrivate(page) __set_bit(PG_private, &(page)->flags)
#define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
+/*
+ * Only test-and-set exist for PG_writeback. The unconditional operators are
+ * risky: they bypass page accounting.
+ */
#define PageWriteback(page) test_bit(PG_writeback, &(page)->flags)
-#define SetPageWriteback(page) \
- do { \
- if (!test_and_set_bit(PG_writeback, \
- &(page)->flags)) \
- inc_page_state(nr_writeback); \
- } while (0)
-#define TestSetPageWriteback(page) \
- ({ \
- int ret; \
- ret = test_and_set_bit(PG_writeback, \
- &(page)->flags); \
- if (!ret) \
- inc_page_state(nr_writeback); \
- ret; \
- })
-#define ClearPageWriteback(page) \
- do { \
- if (test_and_clear_bit(PG_writeback, \
- &(page)->flags)) \
- dec_page_state(nr_writeback); \
- } while (0)
-#define TestClearPageWriteback(page) \
- ({ \
- int ret; \
- ret = test_and_clear_bit(PG_writeback, \
- &(page)->flags); \
- if (ret) \
- dec_page_state(nr_writeback); \
- ret; \
- })
-
-#define PageNosave(page) test_bit(PG_nosave, &(page)->flags)
-#define SetPageNosave(page) set_bit(PG_nosave, &(page)->flags)
-#define TestSetPageNosave(page) test_and_set_bit(PG_nosave, &(page)->flags)
-#define ClearPageNosave(page) clear_bit(PG_nosave, &(page)->flags)
-#define TestClearPageNosave(page) test_and_clear_bit(PG_nosave, &(page)->flags)
-
-#define PageNosaveFree(page) test_bit(PG_nosave_free, &(page)->flags)
-#define SetPageNosaveFree(page) set_bit(PG_nosave_free, &(page)->flags)
-#define ClearPageNosaveFree(page) clear_bit(PG_nosave_free, &(page)->flags)
+#define TestSetPageWriteback(page) test_and_set_bit(PG_writeback, \
+ &(page)->flags)
+#define TestClearPageWriteback(page) test_and_clear_bit(PG_writeback, \
+ &(page)->flags)
#define PageBuddy(page) test_bit(PG_buddy, &(page)->flags)
#define __SetPageBuddy(page) __set_bit(PG_buddy, &(page)->flags)
#define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
#define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
+#define PageReadahead(page) test_bit(PG_readahead, &(page)->flags)
+#define SetPageReadahead(page) set_bit(PG_readahead, &(page)->flags)
+#define ClearPageReadahead(page) clear_bit(PG_readahead, &(page)->flags)
+
#define PageReclaim(page) test_bit(PG_reclaim, &(page)->flags)
#define SetPageReclaim(page) set_bit(PG_reclaim, &(page)->flags)
#define ClearPageReclaim(page) clear_bit(PG_reclaim, &(page)->flags)
#define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags)
#define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags)
+/*
+ * PG_reclaim is used in combination with PG_compound to mark the
+ * head and tail of a compound page
+ *
+ * PG_compound & PG_reclaim => Tail page
+ * PG_compound & ~PG_reclaim => Head page
+ */
+
+#define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
+
+#define PageTail(page) ((page->flags & PG_head_tail_mask) \
+ == PG_head_tail_mask)
+
+static inline void __SetPageTail(struct page *page)
+{
+ page->flags |= PG_head_tail_mask;
+}
+
+static inline void __ClearPageTail(struct page *page)
+{
+ page->flags &= ~PG_head_tail_mask;
+}
+
+#define PageHead(page) ((page->flags & PG_head_tail_mask) \
+ == (1L << PG_compound))
+#define __SetPageHead(page) __SetPageCompound(page)
+#define __ClearPageHead(page) __ClearPageCompound(page)
+
#ifdef CONFIG_SWAP
#define PageSwapCache(page) test_bit(PG_swapcache, &(page)->flags)
#define SetPageSwapCache(page) set_bit(PG_swapcache, &(page)->flags)
struct page; /* forward declaration */
-int test_clear_page_dirty(struct page *page);
+extern void cancel_dirty_page(struct page *page, unsigned int account_size);
+
int test_clear_page_writeback(struct page *page);
int test_set_page_writeback(struct page *page);
-static inline void clear_page_dirty(struct page *page)
-{
- test_clear_page_dirty(page);
-}
-
static inline void set_page_writeback(struct page *page)
{
test_set_page_writeback(page);