fix some conversion overflows

Fix page index to offset conversion overflows in buffer layer, ecryptfs,
and ocfs2.

It would be nice to convert the whole tree to page_offset, but for now
just fix the bugs.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index 02ebb1f1d3b0..0e5ec371ce72 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2221,7 +2221,7 @@ block_page_mkwrite(struct vm_area_struct *vma, struct page *page,
         lock_page(page);
         size = i_size_read(inode);
         if ((page->mapping != inode->i_mapping) ||
-            ((page->index << PAGE_CACHE_SHIFT) > size)) {
+            (page_offset(page) > size)) {
                 /* page got truncated out from underneath us */
                 goto out_unlock;
         }