ext4: set bg_itable_unused when resizing

Set bg_itable_unused for file systems that have uninit_bg enabled.
This will speed up the first e2fsck run after the file system is
resized.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 7adc088..a5be589 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -1268,6 +1268,9 @@
 		ext4_free_group_clusters_set(sb, gdp,
 					     EXT4_B2C(sbi, group_data->free_blocks_count));
 		ext4_free_inodes_set(sb, gdp, EXT4_INODES_PER_GROUP(sb));
+		if (ext4_has_group_desc_csum(sb))
+			ext4_itable_unused_set(sb, gdp,
+					       EXT4_INODES_PER_GROUP(sb));
 		gdp->bg_flags = cpu_to_le16(*bg_flags);
 		ext4_group_desc_csum_set(sb, group, gdp);