Merge branch 'for-linus' of git://neil.brown.name/md

* 'for-linus' of git://neil.brown.name/md:
  md: Don't read past end of bitmap when reading bitmap.

drivers/md/bitmap.c

@@ -208,15 +208,18 @@ static void bitmap_checkfree(struct bitmap *bitmap, unsigned long page)
  */
 
 /* IO operations when bitmap is stored near all superblocks */
-static struct page *read_sb_page(mddev_t *mddev, long offset, unsigned long index)
+static struct page *read_sb_page(mddev_t *mddev, long offset,
+				 struct page *page,
+				 unsigned long index, int size)
 {
 	/* choose a good rdev and read the page from there */
 
 	mdk_rdev_t *rdev;
 	struct list_head *tmp;
-	struct page *page = alloc_page(GFP_KERNEL);
 	sector_t target;
 
+	if (!page)
+		page = alloc_page(GFP_KERNEL);
 	if (!page)
 		return ERR_PTR(-ENOMEM);
 
@@ -227,7 +230,9 @@ static struct page *read_sb_page(mddev_t *mddev, long offset, unsigned long inde
 
 		target = rdev->sb_start + offset + index * (PAGE_SIZE/512);
 
-		if (sync_page_io(rdev->bdev, target, PAGE_SIZE, page, READ)) {
+		if (sync_page_io(rdev->bdev, target,
+				 roundup(size, bdev_hardsect_size(rdev->bdev)),
+				 page, READ)) {
 			page->index = index;
 			attach_page_buffers(page, NULL); /* so that free_buffer will
 							  * quietly no-op */
@@ -544,7 +549,9 @@ static int bitmap_read_sb(struct bitmap *bitmap)
 
 		bitmap->sb_page = read_page(bitmap->file, 0, bitmap, bytes);
 	} else {
-		bitmap->sb_page = read_sb_page(bitmap->mddev, bitmap->offset, 0);
+		bitmap->sb_page = read_sb_page(bitmap->mddev, bitmap->offset,
+					       NULL,
+					       0, sizeof(bitmap_super_t));
 	}
 	if (IS_ERR(bitmap->sb_page)) {
 		err = PTR_ERR(bitmap->sb_page);
@@ -957,11 +964,16 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 				 */
 				page = bitmap->sb_page;
 				offset = sizeof(bitmap_super_t);
+				read_sb_page(bitmap->mddev, bitmap->offset,
+					     page,
+					     index, count);
 			} else if (file) {
 				page = read_page(file, index, bitmap, count);
 				offset = 0;
 			} else {
-				page = read_sb_page(bitmap->mddev, bitmap->offset, index);
+				page = read_sb_page(bitmap->mddev, bitmap->offset,
+						    NULL,
+						    index, count);
 				offset = 0;
 			}
 			if (IS_ERR(page)) { /* read error */