ext4: convert s_{dirty,free}blocks_counter to s_{dirty,free}clusters_counter

Convert the percpu counters s_dirtyblocks_counter and
s_freeblocks_counter in struct ext4_super_info to be
s_dirtyclusters_counter and s_freeclusters_counter.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 030bfc1..c758836 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -855,6 +855,7 @@
 	ext4_group_t	i_last_alloc_group;
 
 	/* allocation reservation info for delalloc */
+	/* In case of bigalloc, these refer to clusters rather than blocks */
 	unsigned int i_reserved_data_blocks;
 	unsigned int i_reserved_meta_blocks;
 	unsigned int i_allocated_meta_blocks;
@@ -1144,10 +1145,10 @@
 	u32 s_hash_seed[4];
 	int s_def_hash_version;
 	int s_hash_unsigned;	/* 3 if hash should be signed, 0 if not */
-	struct percpu_counter s_freeblocks_counter;
+	struct percpu_counter s_freeclusters_counter;
 	struct percpu_counter s_freeinodes_counter;
 	struct percpu_counter s_dirs_counter;
-	struct percpu_counter s_dirtyblocks_counter;
+	struct percpu_counter s_dirtyclusters_counter;
 	struct blockgroup_lock *s_blockgroup_lock;
 	struct proc_dir_entry *s_proc;
 	struct kobject s_kobj;