From: Theodore Ts'o <tytso@mit.edu>
Date: Sun, 16 Feb 2014 03:42:25 +0000 (-0500)
Subject: ext4: fix online resize with a non-standard blocks per group setting
X-Git-Tag: v3.12.14~102
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=50e31fc3f09c418d312d4129d8f01f607087bd5a;p=kernel%2Fkernel-generic.git

ext4: fix online resize with a non-standard blocks per group setting

commit 3d2660d0c9c2f296837078c189b68a47f6b2e3b5 upstream.

The set_flexbg_block_bitmap() function assumed that the number of
blocks in a blockgroup was sb->blocksize * 8, which is normally true,
but not always!  Use EXT4_BLOCKS_PER_GROUP(sb) instead, to fix block
bitmap corruption after:

mke2fs -t ext4 -g 3072 -i 4096 /dev/vdd 1G
mount -t ext4 /dev/vdd /vdd
resize2fs /dev/vdd 8G

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reported-by: Jon Bernard <jbernard@tuxion.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 69a6261..f3b84cd 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -409,7 +409,7 @@ static int set_flexbg_block_bitmap(struct super_block *sb, handle_t *handle,
 		start = ext4_group_first_block_no(sb, group);
 		group -= flex_gd->groups[0].group;
 
-		count2 = sb->s_blocksize * 8 - (block - start);
+		count2 = EXT4_BLOCKS_PER_GROUP(sb) - (block - start);
 		if (count2 > count)
 			count2 = count;