[PATCH 01/12] ext4: add debugfs interface

[Zhang Yi <yi.zhang@xxxxxxxxxx>]

Add debugfs interface support, preparing to introduce fault injection
facility.

Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
---
 fs/ext4/ext4.h  |  1 +
 fs/ext4/sysfs.c | 10 +++++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 8d5453852f98..53099ffe307f 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1551,6 +1551,7 @@ struct ext4_sb_info {
 	struct percpu_counter s_sra_exceeded_retry_limit;
 	struct blockgroup_lock *s_blockgroup_lock;
 	struct proc_dir_entry *s_proc;
+	struct dentry *s_debug;
 	struct kobject s_kobj;
 	struct completion s_kobj_unregister;
 	struct super_block *s_sb;
diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index d233c24ea342..f3e4049ec50e 100644
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -14,6 +14,7 @@
 #include <linux/slab.h>
 #include <linux/proc_fs.h>
 #include <linux/part_stat.h>
+#include <linux/debugfs.h>
 
 #include "ext4.h"
 #include "ext4_jbd2.h"
@@ -59,6 +60,8 @@ struct ext4_attr {
 	} u;
 };
 
+static struct dentry *ext4_debugfs_root;
+
 static ssize_t session_write_kbytes_show(struct ext4_sb_info *sbi, char *buf)
 {
 	struct super_block *sb = sbi->s_buddy_cache->i_sb;
@@ -548,6 +551,8 @@ int ext4_register_sysfs(struct super_block *sb)
 		proc_create_seq_data("mb_structs_summary", 0444, sbi->s_proc,
 				&ext4_mb_seq_structs_summary_ops, sb);
 	}
+	if (ext4_debugfs_root)
+		sbi->s_debug = debugfs_create_dir(sb->s_id, ext4_debugfs_root);
 	return 0;
 }
 
@@ -555,6 +560,7 @@ void ext4_unregister_sysfs(struct super_block *sb)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 
+	debugfs_remove_recursive(sbi->s_debug);
 	if (sbi->s_proc)
 		remove_proc_subtree(sb->s_id, ext4_proc_root);
 	kobject_del(&sbi->s_kobj);
@@ -580,6 +586,7 @@ int __init ext4_init_sysfs(void)
 		goto feat_err;
 
 	ext4_proc_root = proc_mkdir(proc_dirname, NULL);
+	ext4_debugfs_root = debugfs_create_dir("ext4", NULL);
 	return ret;
 
 feat_err:
@@ -599,5 +606,6 @@ void ext4_exit_sysfs(void)
 	ext4_root = NULL;
 	remove_proc_entry(proc_dirname, NULL);
 	ext4_proc_root = NULL;
+	debugfs_remove_recursive(ext4_debugfs_root);
+	ext4_debugfs_root = NULL;
 }
-
-- 
2.31.1