md: don't write more than is required of the last page of a bitmap

It is possible that real data or metadata follows the bitmap without full page
alignment.

So limit the last write to be only the required number of bytes, rounded up to
the hard sector size of the device.

Signed-off-by: Neil Brown <neilb@suse.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/raid/bitmap.h b/include/linux/raid/bitmap.h
index 6db9a4c1535..dd5a05d03d4 100644
--- a/include/linux/raid/bitmap.h
+++ b/include/linux/raid/bitmap.h
@@ -232,6 +232,7 @@ struct bitmap {
         struct page **filemap; /* list of cache pages for the file */
         unsigned long *filemap_attr; /* attributes associated w/ filemap pages */
         unsigned long file_pages; /* number of pages in the file */
+        int last_page_size; /* bytes in the last page */
 
         unsigned long flags;