From: Guoqing Jiang <gqjiang@suse.com>
Date: Mon, 2 May 2016 15:50:13 +0000 (-0400)
Subject: md-cluster/bitmap: fix wrong calcuation of offset
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=7f86ffed9b5f3f0b1a29108c5e965942b935ec98;p=deliverable%2Flinux.git

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 ac93d874578a..cf93bb80aff7 100644
--- 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);