ext4: rearrange initialization to fix EXT4FS_DEBUG

The EXT4FS_DEBUG is a *very* developer specific #ifdef designed for
ext4 developers only.  (You have to modify fs/ext4/ext4.h to enable
it.)

Rearrange how we initialize data structures to avoid calling
ext4_count_free_clusters() until the multiblock allocator has been
initialized.

This also allows us to only call ext4_count_free_clusters() once, and
simplifies the code somewhat.

(Thanks to Chen Gang <gang.chen.5i5j@gmail.com> for pointing out a
!CONFIG_SMP compile breakage in the original patch.)
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>

fs/ext4/super.c

@@ -2142,10 +2142,6 @@ static int ext4_check_descriptors(struct super_block *sb,
 	}
 	if (NULL != first_not_zeroed)
 		*first_not_zeroed = grp;
-
-	ext4_free_blocks_count_set(sbi->s_es,
-				   EXT4_C2B(sbi, ext4_count_free_clusters(sb)));
-	sbi->s_es->s_free_inodes_count =cpu_to_le32(ext4_count_free_inodes(sb));
 	return 1;
 }
 
@@ -3883,13 +3879,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 		ext4_msg(sb, KERN_ERR, "group descriptors corrupted!");
 		goto failed_mount2;
 	}
-	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
-		if (!ext4_fill_flex_info(sb)) {
-			ext4_msg(sb, KERN_ERR,
-			       "unable to initialize "
-			       "flex_bg meta info!");
-			goto failed_mount2;
-		}
 
 	sbi->s_gdb_count = db_count;
 	get_random_bytes(&sbi->s_next_generation, sizeof(u32));
@@ -3902,23 +3891,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	/* Register extent status tree shrinker */
 	ext4_es_register_shrinker(sbi);
 
-	err = percpu_counter_init(&sbi->s_freeclusters_counter,
-			ext4_count_free_clusters(sb));
-	if (!err) {
-		err = percpu_counter_init(&sbi->s_freeinodes_counter,
-				ext4_count_free_inodes(sb));
-	}
-	if (!err) {
-		err = percpu_counter_init(&sbi->s_dirs_counter,
-				ext4_count_dirs(sb));
-	}
-	if (!err) {
-		err = percpu_counter_init(&sbi->s_dirtyclusters_counter, 0);
-	}
-	if (!err) {
-		err = percpu_counter_init(&sbi->s_extent_cache_cnt, 0);
-	}
-	if (err) {
+	if ((err = percpu_counter_init(&sbi->s_extent_cache_cnt, 0)) != 0) {
 		ext4_msg(sb, KERN_ERR, "insufficient memory");
 		goto failed_mount3;
 	}
@@ -4022,18 +3995,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 
 	sbi->s_journal->j_commit_callback = ext4_journal_commit_callback;
 
-	/*
-	 * The journal may have updated the bg summary counts, so we
-	 * need to update the global counters.
-	 */
-	percpu_counter_set(&sbi->s_freeclusters_counter,
-			   ext4_count_free_clusters(sb));
-	percpu_counter_set(&sbi->s_freeinodes_counter,
-			   ext4_count_free_inodes(sb));
-	percpu_counter_set(&sbi->s_dirs_counter,
-			   ext4_count_dirs(sb));
-	percpu_counter_set(&sbi->s_dirtyclusters_counter, 0);
-
 no_journal:
 	if (ext4_mballoc_ready) {
 		sbi->s_mb_cache = ext4_xattr_create_cache(sb->s_id);
@@ -4141,6 +4102,33 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 		goto failed_mount5;
 	}
 
+	block = ext4_count_free_clusters(sb);
+	ext4_free_blocks_count_set(sbi->s_es, 
+				   EXT4_C2B(sbi, block));
+	err = percpu_counter_init(&sbi->s_freeclusters_counter, block);
+	if (!err) {
+		unsigned long freei = ext4_count_free_inodes(sb);
+		sbi->s_es->s_free_inodes_count = cpu_to_le32(freei);
+		err = percpu_counter_init(&sbi->s_freeinodes_counter, freei);
+	}
+	if (!err)
+		err = percpu_counter_init(&sbi->s_dirs_counter,
+					  ext4_count_dirs(sb));
+	if (!err)
+		err = percpu_counter_init(&sbi->s_dirtyclusters_counter, 0);
+	if (err) {
+		ext4_msg(sb, KERN_ERR, "insufficient memory");
+		goto failed_mount6;
+	}
+
+	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
+		if (!ext4_fill_flex_info(sb)) {
+			ext4_msg(sb, KERN_ERR,
+			       "unable to initialize "
+			       "flex_bg meta info!");
+			goto failed_mount6;
+		}
+
 	err = ext4_register_li_request(sb, first_not_zeroed);
 	if (err)
 		goto failed_mount6;
@@ -4215,6 +4203,12 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	ext4_unregister_li_request(sb);
 failed_mount6:
 	ext4_mb_release(sb);
+	if (sbi->s_flex_groups)
+		ext4_kvfree(sbi->s_flex_groups);
+	percpu_counter_destroy(&sbi->s_freeclusters_counter);
+	percpu_counter_destroy(&sbi->s_freeinodes_counter);
+	percpu_counter_destroy(&sbi->s_dirs_counter);
+	percpu_counter_destroy(&sbi->s_dirtyclusters_counter);
 failed_mount5:
 	ext4_ext_release(sb);
 	ext4_release_system_zone(sb);
@@ -4233,12 +4227,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 failed_mount3:
 	ext4_es_unregister_shrinker(sbi);
 	del_timer_sync(&sbi->s_err_report);
-	if (sbi->s_flex_groups)
-		ext4_kvfree(sbi->s_flex_groups);
-	percpu_counter_destroy(&sbi->s_freeclusters_counter);
-	percpu_counter_destroy(&sbi->s_freeinodes_counter);
-	percpu_counter_destroy(&sbi->s_dirs_counter);
-	percpu_counter_destroy(&sbi->s_dirtyclusters_counter);
 	percpu_counter_destroy(&sbi->s_extent_cache_cnt);
 	if (sbi->s_mmp_tsk)
 		kthread_stop(sbi->s_mmp_tsk);
@@ -4556,11 +4544,13 @@ static int ext4_commit_super(struct super_block *sb, int sync)
 	else
 		es->s_kbytes_written =
 			cpu_to_le64(EXT4_SB(sb)->s_kbytes_written);
-	ext4_free_blocks_count_set(es,
+	if (percpu_counter_initialized(&EXT4_SB(sb)->s_freeclusters_counter))
+		ext4_free_blocks_count_set(es,
 			EXT4_C2B(EXT4_SB(sb), percpu_counter_sum_positive(
 				&EXT4_SB(sb)->s_freeclusters_counter)));
-	es->s_free_inodes_count =
-		cpu_to_le32(percpu_counter_sum_positive(
+	if (percpu_counter_initialized(&EXT4_SB(sb)->s_freeinodes_counter))
+		es->s_free_inodes_count =
+			cpu_to_le32(percpu_counter_sum_positive(
 				&EXT4_SB(sb)->s_freeinodes_counter));
 	BUFFER_TRACE(sbh, "marking dirty");
 	ext4_superblock_csum_set(sb);