1 files changed, 246 insertions, 0 deletions

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
new file mode 100644
index 000000000000..0422031161ba
--- /dev/null
+++ b/include/linux/pagemap.h
@@ -0,0 +1,246 @@
+#ifndef _LINUX_PAGEMAP_H
+#define _LINUX_PAGEMAP_H
+
+/*
+ * Copyright 1995 Linus Torvalds
+ */
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/list.h>
+#include <linux/highmem.h>
+#include <linux/compiler.h>
+#include <asm/uaccess.h>
+#include <linux/gfp.h>
+
+/*
+ * Bits in mapping->flags.  The lower __GFP_BITS_SHIFT bits are the page
+ * allocation mode flags.
+ */
+#define AS_EIO          (__GFP_BITS_SHIFT + 0)  /* IO error on async write */
+#define AS_ENOSPC       (__GFP_BITS_SHIFT + 1)  /* ENOSPC on async write */
+
+static inline unsigned int __nocast mapping_gfp_mask(struct address_space * mapping)
+{
+        return mapping->flags & __GFP_BITS_MASK;
+}
+
+/*
+ * This is non-atomic.  Only to be used before the mapping is activated.
+ * Probably needs a barrier...
+ */
+static inline void mapping_set_gfp_mask(struct address_space *m, int mask)
+{
+        m->flags = (m->flags & ~__GFP_BITS_MASK) | mask;
+}
+
+/*
+ * The page cache can done in larger chunks than
+ * one page, because it allows for more efficient
+ * throughput (it can then be mapped into user
+ * space in smaller chunks for same flexibility).
+ *
+ * Or rather, it _will_ be done in larger chunks.
+ */
+#define PAGE_CACHE_SHIFT        PAGE_SHIFT
+#define PAGE_CACHE_SIZE         PAGE_SIZE
+#define PAGE_CACHE_MASK         PAGE_MASK
+#define PAGE_CACHE_ALIGN(addr)  (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK)
+
+#define page_cache_get(page)            get_page(page)
+#define page_cache_release(page)        put_page(page)
+void release_pages(struct page **pages, int nr, int cold);
+
+static inline struct page *page_cache_alloc(struct address_space *x)
+{
+        return alloc_pages(mapping_gfp_mask(x), 0);
+}
+
+static inline struct page *page_cache_alloc_cold(struct address_space *x)
+{
+        return alloc_pages(mapping_gfp_mask(x)|__GFP_COLD, 0);
+}
+
+typedef int filler_t(void *, struct page *);
+
+extern struct page * find_get_page(struct address_space *mapping,
+                                unsigned long index);
+extern struct page * find_lock_page(struct address_space *mapping,
+                                unsigned long index);
+extern struct page * find_trylock_page(struct address_space *mapping,
+                                unsigned long index);
+extern struct page * find_or_create_page(struct address_space *mapping,
+                                unsigned long index, unsigned int gfp_mask);
+unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
+                        unsigned int nr_pages, struct page **pages);
+unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
+                        int tag, unsigned int nr_pages, struct page **pages);
+
+/*
+ * Returns locked page at given index in given cache, creating it if needed.
+ */
+static inline struct page *grab_cache_page(struct address_space *mapping, unsigned long index)
+{
+        return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
+}
+
+extern struct page * grab_cache_page_nowait(struct address_space *mapping,
+                                unsigned long index);
+extern struct page * read_cache_page(struct address_space *mapping,
+                                unsigned long index, filler_t *filler,
+                                void *data);
+extern int read_cache_pages(struct address_space *mapping,
+                struct list_head *pages, filler_t *filler, void *data);
+
+int add_to_page_cache(struct page *page, struct address_space *mapping,
+                                unsigned long index, int gfp_mask);
+int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
+                                unsigned long index, int gfp_mask);
+extern void remove_from_page_cache(struct page *page);
+extern void __remove_from_page_cache(struct page *page);
+
+extern atomic_t nr_pagecache;
+
+#ifdef CONFIG_SMP
+
+#define PAGECACHE_ACCT_THRESHOLD        max(16, NR_CPUS * 2)
+DECLARE_PER_CPU(long, nr_pagecache_local);
+
+/*
+ * pagecache_acct implements approximate accounting for pagecache.
+ * vm_enough_memory() do not need high accuracy. Writers will keep
+ * an offset in their per-cpu arena and will spill that into the
+ * global count whenever the absolute value of the local count
+ * exceeds the counter's threshold.
+ *
+ * MUST be protected from preemption.
+ * current protection is mapping->page_lock.
+ */
+static inline void pagecache_acct(int count)
+{
+        long *local;
+
+        local = &__get_cpu_var(nr_pagecache_local);
+        *local += count;
+        if (*local > PAGECACHE_ACCT_THRESHOLD || *local < -PAGECACHE_ACCT_THRESHOLD) {
+                atomic_add(*local, &nr_pagecache);
+                *local = 0;
+        }
+}
+
+#else
+
+static inline void pagecache_acct(int count)
+{
+        atomic_add(count, &nr_pagecache);
+}
+#endif
+
+static inline unsigned long get_page_cache_size(void)
+{
+        int ret = atomic_read(&nr_pagecache);
+        if (unlikely(ret < 0))
+                ret = 0;
+        return ret;
+}
+
+/*
+ * Return byte-offset into filesystem object for page.
+ */
+static inline loff_t page_offset(struct page *page)
+{
+        return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
+}
+
+static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
+                                        unsigned long address)
+{
+        pgoff_t pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
+        pgoff += vma->vm_pgoff;
+        return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+}
+
+extern void FASTCALL(__lock_page(struct page *page));
+extern void FASTCALL(unlock_page(struct page *page));
+
+static inline void lock_page(struct page *page)
+{
+        might_sleep();
+        if (TestSetPageLocked(page))
+                __lock_page(page);
+}
+        
+/*
+ * This is exported only for wait_on_page_locked/wait_on_page_writeback.
+ * Never use this directly!
+ */
+extern void FASTCALL(wait_on_page_bit(struct page *page, int bit_nr));
+
+/* 
+ * Wait for a page to be unlocked.
+ *
+ * This must be called with the caller "holding" the page,
+ * ie with increased "page->count" so that the page won't
+ * go away during the wait..
+ */
+static inline void wait_on_page_locked(struct page *page)
+{
+        if (PageLocked(page))
+                wait_on_page_bit(page, PG_locked);
+}
+
+/* 
+ * Wait for a page to complete writeback
+ */
+static inline void wait_on_page_writeback(struct page *page)
+{
+        if (PageWriteback(page))
+                wait_on_page_bit(page, PG_writeback);
+}
+
+extern void end_page_writeback(struct page *page);
+
+/*
+ * Fault a userspace page into pagetables.  Return non-zero on a fault.
+ *
+ * This assumes that two userspace pages are always sufficient.  That's
+ * not true if PAGE_CACHE_SIZE > PAGE_SIZE.
+ */
+static inline int fault_in_pages_writeable(char __user *uaddr, int size)
+{
+        int ret;
+
+        /*
+         * Writing zeroes into userspace here is OK, because we know that if
+         * the zero gets there, we'll be overwriting it.
+         */
+        ret = __put_user(0, uaddr);
+        if (ret == 0) {
+                char __user *end = uaddr + size - 1;
+
+                /*
+                 * If the page was already mapped, this will get a cache miss
+                 * for sure, so try to avoid doing it.
+                 */
+                if (((unsigned long)uaddr & PAGE_MASK) !=
+                                ((unsigned long)end & PAGE_MASK))
+                        ret = __put_user(0, end);
+        }
+        return ret;
+}
+
+static inline void fault_in_pages_readable(const char __user *uaddr, int size)
+{
+        volatile char c;
+        int ret;
+
+        ret = __get_user(c, uaddr);
+        if (ret == 0) {
+                const char __user *end = uaddr + size - 1;
+
+                if (((unsigned long)uaddr & PAGE_MASK) !=
+                                ((unsigned long)end & PAGE_MASK))
+                        __get_user(c, end);
+        }
+}
+
+#endif /* _LINUX_PAGEMAP_H */