Update flex_bg free blocks and free inodes counters when resizing.

This fixes a bug which prevented the newly created inodes after a
resize from being used on filesystems with flex_bg.

Signed-off-by: Frederic Bohe <frederic.bohe@bull.net>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index efa40d9..f58cc03 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1507,8 +1507,11 @@
 	sbi->s_log_groups_per_flex = sbi->s_es->s_log_groups_per_flex;
 	groups_per_flex = 1 << sbi->s_log_groups_per_flex;
 
-	flex_group_count = (sbi->s_groups_count + groups_per_flex - 1) /
-		groups_per_flex;
+	/* We allocate both existing and potentially added groups */
+	flex_group_count = ((sbi->s_groups_count + groups_per_flex - 1) +
+			    ((sbi->s_es->s_reserved_gdt_blocks +1 ) <<
+			      EXT4_DESC_PER_BLOCK_BITS(sb))) /
+			   groups_per_flex;
 	sbi->s_flex_groups = kzalloc(flex_group_count *
 				     sizeof(struct flex_groups), GFP_KERNEL);
 	if (sbi->s_flex_groups == NULL) {