2 files changed, 13 insertions, 5 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 5a4a74c1097c..9620d452d030 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -255,19 +255,25 @@ static struct page *read_sb_page(mddev_t *mddev, long offset, unsigned long inde
 
 }
 
-static int write_sb_page(mddev_t *mddev, long offset, struct page *page, int wait)
+static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
 {
         mdk_rdev_t *rdev;
         struct list_head *tmp;
+        mddev_t *mddev = bitmap->mddev;
 
         ITERATE_RDEV(mddev, rdev, tmp)
                 if (test_bit(In_sync, &rdev->flags)
-                    && !test_bit(Faulty, &rdev->flags))
+                    && !test_bit(Faulty, &rdev->flags)) {
+                        int size = PAGE_SIZE;
+                        if (page->index == bitmap->file_pages-1)
+                                size = roundup(bitmap->last_page_size,
+                                               bdev_hardsect_size(rdev->bdev));
                         md_super_write(mddev, rdev,
-                                       (rdev->sb_offset<<1) + offset
+                                       (rdev->sb_offset<<1) + bitmap->offset
                                        + page->index * (PAGE_SIZE/512),
-                                       PAGE_SIZE,
+                                       size,
                                        page);
+                }
 
         if (wait)
                 md_super_wait(mddev);
@@ -282,7 +288,7 @@ static int write_page(struct bitmap *bitmap, struct page *page, int wait)
         struct buffer_head *bh;
 
         if (bitmap->file == NULL)
-                return write_sb_page(bitmap->mddev, bitmap->offset, page, wait);
+                return write_sb_page(bitmap, page, wait);
 
         bh = page_buffers(page);
 
@@ -923,6 +929,7 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
                         }
 
                         bitmap->filemap[bitmap->file_pages++] = page;
+                        bitmap->last_page_size = count;
                 }
                 paddr = kmap_atomic(page, KM_USER0);
                 if (bitmap->flags & BITMAP_HOSTENDIAN)
diff --git a/include/linux/raid/bitmap.h b/include/linux/raid/bitmap.h
index 6db9a4c15355..dd5a05d03d4f 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;