[PATCH] filemap : fix the wrong offset

[Huang Shijie <shijie8@gmail.com>]

The offset should be in PAGE_CACHE_SHIFT unit, not in PAGE_SHIFT unit.

Though we do not fully implement the page cache in larger chunks,
but in the vma_address(), all the pages do the (PAGE_CACHE_SHIFT - PAGE_SHIFT) shift,
so do a reverse operation in filemap_fault() is needed.

Signed-off-by: Huang Shijie <shijie8@gmail.com>
---
 mm/filemap.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index ef169f3..2d8385e 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1502,7 +1502,7 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	struct address_space *mapping = file->f_mapping;
 	struct file_ra_state *ra = &file->f_ra;
 	struct inode *inode = mapping->host;
-	pgoff_t offset = vmf->pgoff;
+	pgoff_t offset = vmf->pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
 	struct page *page;
 	pgoff_t size;
 	int ret = 0;
-- 
1.6.0.6

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