[PATCH 05/25] Unionfs: cast page->index loff_t before shifting

[Erez Zadok <ezk@cs.sunysb.edu>]

Fixes bugs in number promotion/demotion computation, as per
<http://lkml.org/lkml/2007/9/20/17>

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Acked-by: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
---
 fs/unionfs/mmap.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/unionfs/mmap.c b/fs/unionfs/mmap.c
index 88ef6a6..37af979 100644
--- a/fs/unionfs/mmap.c
+++ b/fs/unionfs/mmap.c
@@ -179,7 +179,8 @@ static int unionfs_do_readpage(struct file *file, struct page *page)
 	 * may be a little slower, but a lot safer, as the VFS does a lot of
 	 * the necessary magic for us.
 	 */
-	offset = lower_file->f_pos = (page->index << PAGE_CACHE_SHIFT);
+	offset = lower_file->f_pos =
+		((loff_t) page->index << PAGE_CACHE_SHIFT);
 	old_fs = get_fs();
 	set_fs(KERNEL_DS);
 	err = vfs_read(lower_file, page_data, PAGE_CACHE_SIZE,
@@ -289,7 +290,7 @@ static int unionfs_commit_write(struct file *file, struct page *page,
 	BUG_ON(lower_file == NULL);
 
 	page_data = (char *)kmap(page);
-	lower_file->f_pos = (page->index << PAGE_CACHE_SHIFT) + from;
+	lower_file->f_pos = ((loff_t) page->index << PAGE_CACHE_SHIFT) + from;
 
 	/*
 	 * SP: I use vfs_write instead of copying page data and the
-- 
1.5.2.2

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