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Subject[PATCH] [12/19] HWPOISON: Add invalidate_inode_page
Date

From: Wu Fengguang <fengguang.wu@intel.com>

Add a simple way to invalidate a single page
This is just a refactoring of the truncate.c code.
Originally from Fengguang, modified by Andi Kleen.

Signed-off-by: Andi Kleen <ak@linux.intel.com>

---
include/linux/mm.h | 2 ++
mm/truncate.c | 26 ++++++++++++++++++++------
2 files changed, 22 insertions(+), 6 deletions(-)
Index: linux/include/linux/mm.h
===================================================================
--- linux.orig/include/linux/mm.h
+++ linux/include/linux/mm.h
@@ -811,6 +811,8 @@ extern int vmtruncate_range(struct inode

int truncate_inode_page(struct address_space *mapping, struct page *page);

+int invalidate_inode_page(struct page *page);
+
#ifdef CONFIG_MMU
extern int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, unsigned int flags);
Index: linux/mm/truncate.c
===================================================================
--- linux.orig/mm/truncate.c
+++ linux/mm/truncate.c
@@ -146,6 +146,24 @@ int truncate_inode_page(struct address_s
return truncate_complete_page(mapping, page);
}

+/*
+ * Safely invalidate one page from its pagecache mapping.
+ * It only drops clean, unused pages. The page must be locked.
+ *
+ * Returns 1 if the page is successfully invalidated, otherwise 0.
+ */
+int invalidate_inode_page(struct page *page)
+{
+ struct address_space *mapping = page_mapping(page);
+ if (!mapping)
+ return 0;
+ if (PageDirty(page) || PageWriteback(page))
+ return 0;
+ if (page_mapped(page))
+ return 0;
+ return invalidate_complete_page(mapping, page);
+}
+
/**
* truncate_inode_pages - truncate range of pages specified by start & end byte offsets
* @mapping: mapping to truncate
@@ -312,12 +330,8 @@ unsigned long invalidate_mapping_pages(s
if (lock_failed)
continue;

- if (PageDirty(page) || PageWriteback(page))
- goto unlock;
- if (page_mapped(page))
- goto unlock;
- ret += invalidate_complete_page(mapping, page);
-unlock:
+ ret += invalidate_inode_page(page);
+
unlock_page(page);
if (next > end)
break;

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