ext4: Free resources in ext4_mb_init()'s error paths

In commit 79a77c5a, we move ext4_mb_init_backend after the allocation
of s_locality_group to avoid memory leak in error path, but there are
still some other error paths in ext4_mb_init that need to do the same
work. So this patch adds all the error patch for ext4_mb_init. And all
the pointers are reset to NULL in case the caller may double free them.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/mballoc.c

@@ -2504,7 +2504,7 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
 	sbi->s_locality_groups = alloc_percpu(struct ext4_locality_group);
 	if (sbi->s_locality_groups == NULL) {
 		ret = -ENOMEM;
-		goto out;
+		goto out_free_groupinfo_slab;
 	}
 	for_each_possible_cpu(i) {
 		struct ext4_locality_group *lg;
@@ -2517,9 +2517,8 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
 
 	/* init file for buddy data */
 	ret = ext4_mb_init_backend(sb);
-	if (ret != 0) {
-		goto out;
-	}
+	if (ret != 0)
+		goto out_free_locality_groups;
 
 	if (sbi->s_proc)
 		proc_create_data("mb_groups", S_IRUGO, sbi->s_proc,
@@ -2527,11 +2526,19 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
 
 	if (sbi->s_journal)
 		sbi->s_journal->j_commit_callback = release_blocks_on_commit;
+
+	return 0;
+
+out_free_locality_groups:
+	free_percpu(sbi->s_locality_groups);
+	sbi->s_locality_groups = NULL;
+out_free_groupinfo_slab:
+	ext4_groupinfo_destroy_slabs();
 out:
-	if (ret) {
-		kfree(sbi->s_mb_offsets);
-		kfree(sbi->s_mb_maxs);
-	}
+	kfree(sbi->s_mb_offsets);
+	sbi->s_mb_offsets = NULL;
+	kfree(sbi->s_mb_maxs);
+	sbi->s_mb_maxs = NULL;
 	return ret;
 }