md-cluster/bitmap: fix wrong calcuation of offset

The offset is wrong in bitmap_storage_alloc, we should
set it like below in bitmap_init_from_disk().

node_offset = bitmap->cluster_slot * (DIV_ROUND_UP(store->bytes, PAGE_SIZE));

Because 'offset' is only assigned to 'page->index' and
that is usually over-written by read_sb_page. So it does
not cause problem in general, but it still need to be fixed.

Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index ac93d87..cf93bb8 100644 (file)
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -759,7 +759,7 @@ static int bitmap_storage_alloc(struct bitmap_storage *store,
                bytes += sizeof(bitmap_super_t);
 
        num_pages = DIV_ROUND_UP(bytes, PAGE_SIZE);
-       offset = slot_number * (num_pages - 1);
+       offset = slot_number * num_pages;
 
        store->filemap = kmalloc(sizeof(struct page *)
                                 * num_pages, GFP_KERNEL);