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Subject[PATCH 11/22] HWPOISON: Refactor truncate to allow direct truncating of page v3
From: Nick Piggin <npiggin@suse.de>

Extract out truncate_inode_page() out of the truncate path so that
it can be used by memory-failure.c

[AK: description, headers, fix typos]
v2: Some white space changes from Fengguang Wu
v3: add comments

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
include/linux/mm.h | 2 ++
mm/truncate.c | 34 ++++++++++++++++++++++------------
2 files changed, 24 insertions(+), 12 deletions(-)
--- sound-2.6.orig/mm/truncate.c
+++ sound-2.6/mm/truncate.c
@@ -135,6 +135,26 @@ invalidate_complete_page(struct address_
return ret;
}

+/*
+ * Remove one page from its pagecache mapping. The page must be locked.
+ * This does not truncate the file on disk, it performs the pagecache
+ * side of the truncate operation. Dirty data will be discarded, and
+ * concurrent page references are ignored.
+ *
+ * Generic mm/fs code cannot call this on filesystem metadata mappings
+ * because those can assume that a page reference is enough to pin the
+ * page to its mapping.
+ */
+void truncate_inode_page(struct address_space *mapping, struct page *page)
+{
+ if (page_mapped(page)) {
+ unmap_mapping_range(mapping,
+ (loff_t)page->index << PAGE_CACHE_SHIFT,
+ PAGE_CACHE_SIZE, 0);
+ }
+ truncate_complete_page(mapping, page);
+}
+
/**
* truncate_inode_pages - truncate range of pages specified by start & end byte offsets
* @mapping: mapping to truncate
@@ -196,12 +216,7 @@ void truncate_inode_pages_range(struct a
unlock_page(page);
continue;
}
- if (page_mapped(page)) {
- unmap_mapping_range(mapping,
- (loff_t)page_index<<PAGE_CACHE_SHIFT,
- PAGE_CACHE_SIZE, 0);
- }
- truncate_complete_page(mapping, page);
+ truncate_inode_page(mapping, page);
unlock_page(page);
}
pagevec_release(&pvec);
@@ -238,15 +253,10 @@ void truncate_inode_pages_range(struct a
break;
lock_page(page);
wait_on_page_writeback(page);
- if (page_mapped(page)) {
- unmap_mapping_range(mapping,
- (loff_t)page->index<<PAGE_CACHE_SHIFT,
- PAGE_CACHE_SIZE, 0);
- }
+ truncate_inode_page(mapping, page);
if (page->index > next)
next = page->index;
next++;
- truncate_complete_page(mapping, page);
unlock_page(page);
}
pagevec_release(&pvec);
--- sound-2.6.orig/include/linux/mm.h
+++ sound-2.6/include/linux/mm.h
@@ -814,6 +814,8 @@ static inline void unmap_shared_mapping_
extern int vmtruncate(struct inode * inode, loff_t offset);
extern int vmtruncate_range(struct inode * inode, loff_t offset, loff_t end);

+void truncate_inode_page(struct address_space *mapping, struct page *page);
+
#ifdef CONFIG_MMU
extern int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, int write_access);
--



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