1 files changed, 8 insertions, 4 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 5432d07c074d..11108165e264 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -479,9 +479,12 @@ static int bitmap_read_sb(struct bitmap *bitmap)
         int err = -EINVAL;
 
         /* page 0 is the superblock, read it... */
-        if (bitmap->file)
-                bitmap->sb_page = read_page(bitmap->file, 0, bitmap, PAGE_SIZE);
-        else {
+        if (bitmap->file) {
+                loff_t isize = i_size_read(bitmap->file->f_mapping->host);
+                int bytes = isize > PAGE_SIZE ? PAGE_SIZE : isize;
+
+                bitmap->sb_page = read_page(bitmap->file, 0, bitmap, bytes);
+        } else {
                 bitmap->sb_page = read_sb_page(bitmap->mddev, bitmap->offset, 0);
         }
         if (IS_ERR(bitmap->sb_page)) {
@@ -877,7 +880,8 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
                         int count;
                         /* unmap the old page, we're done with it */
                         if (index == num_pages-1)
-                                count = bytes - index * PAGE_SIZE;
+                                count = bytes + sizeof(bitmap_super_t)
+                                        - index * PAGE_SIZE;
                         else
                                 count = PAGE_SIZE;
                         if (index == 0) {