ocfs2: make __ocfs2_page_mkwrite handle file end properly.

__ocfs2_page_mkwrite now is broken in handling file end.
1. the last page should be the page contains i_size - 1.
2. the len in the last page is also calculated wrong.
So change them accordingly.

Acked-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Tao Ma <tao.ma@oracle.com>

diff --git a/fs/ocfs2/mmap.c b/fs/ocfs2/mmap.c
index af2b8fe1f13999e26f6e2543a047847bcf517c4e..4c18f4ad93b43cae6e5ddcd5a2781fbc79292484 100644 (file)
--- a/fs/ocfs2/mmap.c
+++ b/fs/ocfs2/mmap.c
@@ -74,9 +74,11 @@ static int __ocfs2_page_mkwrite(struct inode *inode, struct buffer_head *di_bh,
        /*
         * Another node might have truncated while we were waiting on
         * cluster locks.
+        * We don't check size == 0 before the shift. This is borrowed
+        * from do_generic_file_read.
         */
-       last_index = size >> PAGE_CACHE_SHIFT;
-       if (page->index > last_index) {
+       last_index = (size - 1) >> PAGE_CACHE_SHIFT;
+       if (unlikely(!size || page->index > last_index)) {
                ret = -EINVAL;
                goto out;
        }
@@ -107,7 +109,7 @@ static int __ocfs2_page_mkwrite(struct inode *inode, struct buffer_head *di_bh,
         * because the "write" would invalidate their data.
         */
        if (page->index == last_index)
-               len = size & ~PAGE_CACHE_MASK;
+               len = ((size - 1) & ~PAGE_CACHE_MASK) + 1;
 
        ret = ocfs2_write_begin_nolock(mapping, pos, len, 0, &locked_page,
                                       &fsdata, di_bh, page);