[PATCH] mm: tracking shared dirty pages

[pandora-kernel.git] / include / linux / mm.h

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 224178a..4498414 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -15,6 +15,7 @@
 #include <linux/fs.h>
 #include <linux/mutex.h>
 #include <linux/debug_locks.h>
+#include <linux/backing-dev.h>
 
 struct mempolicy;
 struct anon_vma;
@@ -278,6 +279,12 @@ struct page {
  */
 #include <linux/page-flags.h>
 
+#ifdef CONFIG_DEBUG_VM
+#define VM_BUG_ON(cond) BUG_ON(cond)
+#else
+#define VM_BUG_ON(condition) do { } while(0)
+#endif
+
 /*
  * Methods to modify the page usage count.
  *
@@ -297,7 +304,7 @@ struct page {
  */
 static inline int put_page_testzero(struct page *page)
 {
-       BUG_ON(atomic_read(&page->_count) == 0);
+       VM_BUG_ON(atomic_read(&page->_count) == 0);
        return atomic_dec_and_test(&page->_count);
 }
 
@@ -307,6 +314,7 @@ static inline int put_page_testzero(struct page *page)
  */
 static inline int get_page_unless_zero(struct page *page)
 {
+       VM_BUG_ON(PageCompound(page));
        return atomic_inc_not_zero(&page->_count);
 }
 
@@ -323,6 +331,7 @@ static inline void get_page(struct page *page)
 {
        if (unlikely(PageCompound(page)))
                page = (struct page *)page_private(page);
+       VM_BUG_ON(atomic_read(&page->_count) == 0);
        atomic_inc(&page->_count);
 }
 
@@ -802,6 +811,39 @@ struct shrinker;
 extern struct shrinker *set_shrinker(int, shrinker_t);
 extern void remove_shrinker(struct shrinker *shrinker);
 
+/*
+ * Some shared mappigns will want the pages marked read-only
+ * to track write events. If so, we'll downgrade vm_page_prot
+ * to the private version (using protection_map[] without the
+ * VM_SHARED bit).
+ */
+static inline int vma_wants_writenotify(struct vm_area_struct *vma)
+{
+       unsigned int vm_flags = vma->vm_flags;
+
+       /* If it was private or non-writable, the write bit is already clear */
+       if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
+               return 0;
+
+       /* The backer wishes to know when pages are first written to? */
+       if (vma->vm_ops && vma->vm_ops->page_mkwrite)
+               return 1;
+
+       /* The open routine did something to the protections already? */
+       if (pgprot_val(vma->vm_page_prot) !=
+           pgprot_val(protection_map[vm_flags &
+                   (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]))
+               return 0;
+
+       /* Specialty mapping? */
+       if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
+               return 0;
+
+       /* Can the mapping track the dirty pages? */
+       return vma->vm_file && vma->vm_file->f_mapping &&
+               mapping_cap_account_dirty(vma->vm_file->f_mapping);
+}
+
 extern pte_t *FASTCALL(get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl));
 
 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address);