[PATCH 6/6] fanotify: add current_user_instances node

[Guowei Du <duguoweisz@gmail.com>]

From: duguowei <duguowei@xiaomi.com>

Add a node of sysctl, which is current_user_instances.
It shows current initialized group counts of system.

Signed-off-by: duguowei <duguowei@xiaomi.com>
---
 fs/notify/fanotify/fanotify_user.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index c2255b440df9..39674fbffc4f 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -51,6 +51,8 @@
 
 /* configurable via /proc/sys/fs/fanotify/ */
 static int fanotify_max_queued_events __read_mostly;
+/* current initialized group count */
+static int fanotify_user_instances __read_mostly;
 
 #ifdef CONFIG_SYSCTL
 
@@ -86,6 +88,14 @@ static struct ctl_table fanotify_table[] = {
 		.proc_handler	= proc_dointvec_minmax,
 		.extra1		= SYSCTL_ZERO
 	},
+	{
+		.procname	= "current_user_instances",
+		.data		= &fanotify_user_instances,
+		.maxlen		= sizeof(int),
+		.mode		= 0444,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO
+	},
 	{ }
 };
 
@@ -905,6 +915,8 @@ static int fanotify_release(struct inode *ignored, struct file *file)
 	/* matches the fanotify_init->fsnotify_alloc_group */
 	fsnotify_destroy_group(group);
 
+	fanotify_user_instances--;
+
 	return 0;
 }
 
@@ -1459,6 +1471,8 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 	if (fd < 0)
 		goto out_destroy_group;
 
+	fanotify_user_instances++;
+
 	return fd;
 
 out_destroy_group:
-- 
2.36.1