>From 45e5a255b004e0d578007576304a6b1e272fcb67 Mon Sep 17 00:00:00 2001
From: Izik Eidus <[EMAIL PROTECTED]>
Date: Mon, 21 Jan 2008 16:59:35 +0200
Subject: [PATCH] rmap: add new exported function: page_wrprotect(),
page_wrprotect() make the page as read only by setting the ptes point to
it as read only.
Signed-off-by: Izik Eidus <[EMAIL PROTECTED]>
---
include/linux/rmap.h | 7 ++++
mm/rmap.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 98 insertions(+), 0 deletions(-)
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 97347f2..dac41af 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -108,6 +108,8 @@ unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
*/
int page_mkclean(struct page *);
+int page_wrprotect(struct page *page);
+
#else /* !CONFIG_MMU */
#define anon_vma_init() do {} while (0)
@@ -122,6 +124,11 @@ static inline int page_mkclean(struct page *page)
return 0;
}
+static inline int page_wrprotect(struct page *page)
+{
+ return 0;
+}
+
#endif /* CONFIG_MMU */
diff --git a/mm/rmap.c b/mm/rmap.c
index dbc2ca2..462b7c9 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -484,6 +484,97 @@ int page_mkclean(struct page *page)
}
EXPORT_SYMBOL_GPL(page_mkclean);
+static int page_wrprotect_one(struct page *page, struct vm_area_struct *vma)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long address;
+ pte_t *pte;
+ spinlock_t *ptl;
+ int ret = 0;
+
+ address = vma_address(page, vma);
+ if (address == -EFAULT)
+ goto out;
+
+ pte = page_check_address(page, mm, address, &ptl);
+ if (!pte)
+ goto out;
+
+ if (pte_write(*pte)) {
+ pte_t entry;
+
+ flush_cache_page(vma, address, pte_pfn(*pte));
+ entry = ptep_clear_flush(vma, address, pte);
+ entry = pte_wrprotect(entry);
+ set_pte_at(mm, address, pte, entry);
+ }
+ ret = 1;
+
+ pte_unmap_unlock(pte, ptl);
+out:
+ return ret;
+}
+
+static int page_wrprotect_file(struct page *page)
+{
+ struct address_space *mapping;
+ struct prio_tree_iter iter;
+ struct vm_area_struct *vma;
+ pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+ int ret = 0;
+
+ mapping = page_mapping(page);
+ if (!mapping)
+ return ret;
+
+ spin_lock(&mapping->i_mmap_lock);
+
+ vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff)
+ ret += page_wrprotect_one(page, vma);
+
+ spin_unlock(&mapping->i_mmap_lock);
+
+ return ret;
+}
+
+static int page_wrprotect_anon(struct page *page)
+{
+ struct vm_area_struct *vma;
+ struct anon_vma *anon_vma;
+ int ret = 0;
+
+ anon_vma = page_lock_anon_vma(page);
+ if (!anon_vma)
+ return ret;
+
+ list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
+ ret += page_wrprotect_one(page, vma);
+
+ page_unlock_anon_vma(anon_vma);
+
+ return ret;
+}
+
+/**
+ * set all the ptes pointed to a page as read only
+ * return the number of ptes that were set as read only
+ * (ptes that were read only before this was called are counted as well)
+ */
+int page_wrprotect(struct page *page)
+{
+ int ret = 0;
+
+ BUG_ON(!PageLocked(page));
+
+ if (PageAnon(page))
+ ret = page_wrprotect_anon(page);
+ else
+ ret = page_wrprotect_file(page);
+
+ return ret;
+}
+EXPORT_SYMBOL(page_wrprotect);
+
/**
* page_set_anon_rmap - setup new anonymous rmap
* @page: the page to add the mapping to
--
1.5.3.6
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