ext4: Convert s_blocks_count to s_blocks_count_lo

Convert s_blocks_count to s_blocks_count_lo
This helps in finding BUGs due to direct partial access of
these split 64 bit values

Also fix direct partial access in ext4 code

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index f9cb64c..11e80f0 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2667,7 +2667,7 @@
 
 	if (test_opt(sb, MINIX_DF)) {
 		sbi->s_overhead_last = 0;
-	} else if (sbi->s_blocks_last != le32_to_cpu(es->s_blocks_count)) {
+	} else if (sbi->s_blocks_last != ext4_blocks_count(es)) {
 		unsigned long ngroups = sbi->s_groups_count, i;
 		ext4_fsblk_t overhead = 0;
 		smp_rmb();
@@ -2702,7 +2702,7 @@
 		overhead += ngroups * (2 + sbi->s_itb_per_group);
 		sbi->s_overhead_last = overhead;
 		smp_wmb();
-		sbi->s_blocks_last = le32_to_cpu(es->s_blocks_count);
+		sbi->s_blocks_last = ext4_blocks_count(es);
 	}
 
 	buf->f_type = EXT4_SUPER_MAGIC;