Re: [PATCH v2 6/8] inotify: simplify subdirectory registration with register_sysctl()

[Luis Chamberlain]

On Wed, Nov 24, 2021 at 10:44:09AM +0100, Jan Kara wrote:
> On Tue 23-11-21 12:24:20, Luis Chamberlain wrote:
> > From: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
> > 
> > There is no need to user boiler plate code to specify a set of base
> > directories we're going to stuff sysctls under. Simplify this by using
> > register_sysctl() and specifying the directory path directly.
> > 
> > Move inotify_user sysctl to inotify_user.c while at it to remove clutter
> > from kernel/sysctl.c.
> > 
> > Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
> > [mcgrof: update commit log to reflect new path we decided to take]
> > Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
> 
> This looks fishy. You register inotify_table but not fanotify_table and
> remove both...

Indeed, the following was missing, I'll roll it in:

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 559bc1e9926d..a35693eb1f36 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -59,7 +59,7 @@ static int fanotify_max_queued_events __read_mostly;
 static long ft_zero = 0;
 static long ft_int_max = INT_MAX;
 
-struct ctl_table fanotify_table[] = {
+static struct ctl_table fanotify_table[] = {
 	{
 		.procname	= "max_user_groups",
 		.data	= &init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS],
@@ -88,6 +88,13 @@ struct ctl_table fanotify_table[] = {
 	},
 	{ }
 };
+
+static void __init fanotify_sysctls_init(void)
+{
+	register_sysctl("fs/fanotify", fanotify_table);
+}
+#else
+#define fanotify_sysctls_init() do { } while (0)
 #endif /* CONFIG_SYSCTL */
 
 /*
@@ -1685,6 +1692,7 @@ static int __init fanotify_user_setup(void)
 	init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS] =
 					FANOTIFY_DEFAULT_MAX_GROUPS;
 	init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS] = max_marks;
+	fanotify_sysctls_init();
 
 	return 0;
 }
diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index 616af2ea20f3..556cc63c88ee 100644
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -5,8 +5,6 @@
 #include <linux/sysctl.h>
 #include <uapi/linux/fanotify.h>
 
-extern struct ctl_table fanotify_table[]; /* for sysctl */
-
 #define FAN_GROUP_FLAG(group, flag) \
 	((group)->fanotify_data.flags & (flag))