ext4: Convert s_r_blocks_count and s_free_blocks_count

Convert s_r_blocks_count and s_free_blocks_count to
s_r_blocks_count_lo and s_free_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>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 11e80f0..b11e9e2 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2709,7 +2709,7 @@
 	buf->f_bsize = sb->s_blocksize;
 	buf->f_blocks = ext4_blocks_count(es) - sbi->s_overhead_last;
 	buf->f_bfree = percpu_counter_sum_positive(&sbi->s_freeblocks_counter);
-	es->s_free_blocks_count = cpu_to_le32(buf->f_bfree);
+	ext4_free_blocks_count_set(es, buf->f_bfree);
 	buf->f_bavail = buf->f_bfree - ext4_r_blocks_count(es);
 	if (buf->f_bfree < ext4_r_blocks_count(es))
 		buf->f_bavail = 0;