ext4: remove unnecessary ext4_get_group_info in ext4_mb_load_buddy

ext4_mb_load_buddy() calls ext4_get_group_info() for setting both
"grp" and "e4b->bd_info", but it could do "e4b->bd_info = grp".
Reported-by: NAndreas Dilger <adilger@whamcloud.com>
Signed-off-by: NTao Ma <boyu.mt@taobao.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/mballoc.c

@@ -1126,7 +1126,7 @@ ext4_mb_load_buddy(struct super_block *sb, ext4_group_t group,
 	grp = ext4_get_group_info(sb, group);
 
 	e4b->bd_blkbits = sb->s_blocksize_bits;
-	e4b->bd_info = ext4_get_group_info(sb, group);
+	e4b->bd_info = grp;
 	e4b->bd_sb = sb;
 	e4b->bd_group = group;
 	e4b->bd_buddy_page = NULL;