sysfs.c
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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2019 Hammerspace Inc
*/
#include <linux/module.h>
#include <linux/kobject.h>
#include <linux/sysfs.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/string.h>
#include <linux/nfs_fs.h>
#include <linux/rcupdate.h>
#include "nfs4_fs.h"
#include "netns.h"
#include "sysfs.h"
struct kobject *nfs_client_kobj;
static struct kset *nfs_client_kset;
static void nfs_netns_object_release(struct kobject *kobj)
{
kfree(kobj);
}
static const struct kobj_ns_type_operations *nfs_netns_object_child_ns_type(
struct kobject *kobj)
{
return &net_ns_type_operations;
}
static struct kobj_type nfs_netns_object_type = {
.release = nfs_netns_object_release,
.sysfs_ops = &kobj_sysfs_ops,
.child_ns_type = nfs_netns_object_child_ns_type,
};
static struct kobject *nfs_netns_object_alloc(const char *name,
struct kset *kset, struct kobject *parent)
{
struct kobject *kobj;
kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
if (kobj) {
kobj->kset = kset;
if (kobject_init_and_add(kobj, &nfs_netns_object_type,
parent, "%s", name) == 0)
return kobj;
kobject_put(kobj);
}
return NULL;
}
int nfs_sysfs_init(void)
{
nfs_client_kset = kset_create_and_add("nfs", NULL, fs_kobj);
if (!nfs_client_kset)
return -ENOMEM;
nfs_client_kobj = nfs_netns_object_alloc("net", nfs_client_kset, NULL);
if (!nfs_client_kobj) {
kset_unregister(nfs_client_kset);
nfs_client_kset = NULL;
return -ENOMEM;
}
return 0;
}
void nfs_sysfs_exit(void)
{
kobject_put(nfs_client_kobj);
kset_unregister(nfs_client_kset);
}
static ssize_t nfs_netns_identifier_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
struct nfs_netns_client *c = container_of(kobj,
struct nfs_netns_client,
kobject);
ssize_t ret;
rcu_read_lock();
ret = scnprintf(buf, PAGE_SIZE, "%s\n", rcu_dereference(c->identifier));
rcu_read_unlock();
return ret;
}
/* Strip trailing '\n' */
static size_t nfs_string_strip(const char *c, size_t len)
{
while (len > 0 && c[len-1] == '\n')
--len;
return len;
}
static ssize_t nfs_netns_identifier_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
struct nfs_netns_client *c = container_of(kobj,
struct nfs_netns_client,
kobject);
const char *old;
char *p;
size_t len;
len = nfs_string_strip(buf, min_t(size_t, count, CONTAINER_ID_MAXLEN));
if (!len)
return 0;
p = kmemdup_nul(buf, len, GFP_KERNEL);
if (!p)
return -ENOMEM;
old = rcu_dereference_protected(xchg(&c->identifier, (char __rcu *)p), 1);
if (old) {
synchronize_rcu();
kfree(old);
}
return count;
}
static void nfs_netns_client_release(struct kobject *kobj)
{
struct nfs_netns_client *c = container_of(kobj,
struct nfs_netns_client,
kobject);
kfree(rcu_dereference_raw(c->identifier));
kfree(c);
}
static const void *nfs_netns_client_namespace(struct kobject *kobj)
{
return container_of(kobj, struct nfs_netns_client, kobject)->net;
}
static struct kobj_attribute nfs_netns_client_id = __ATTR(identifier,
0644, nfs_netns_identifier_show, nfs_netns_identifier_store);
static struct attribute *nfs_netns_client_attrs[] = {
&nfs_netns_client_id.attr,
NULL,
};
static struct kobj_type nfs_netns_client_type = {
.release = nfs_netns_client_release,
.default_attrs = nfs_netns_client_attrs,
.sysfs_ops = &kobj_sysfs_ops,
.namespace = nfs_netns_client_namespace,
};
static struct nfs_netns_client *nfs_netns_client_alloc(struct kobject *parent,
struct net *net)
{
struct nfs_netns_client *p;
p = kzalloc(sizeof(*p), GFP_KERNEL);
if (p) {
p->net = net;
p->kobject.kset = nfs_client_kset;
if (kobject_init_and_add(&p->kobject, &nfs_netns_client_type,
parent, "nfs_client") == 0)
return p;
kobject_put(&p->kobject);
}
return NULL;
}
void nfs_netns_sysfs_setup(struct nfs_net *netns, struct net *net)
{
struct nfs_netns_client *clp;
clp = nfs_netns_client_alloc(nfs_client_kobj, net);
if (clp) {
netns->nfs_client = clp;
kobject_uevent(&clp->kobject, KOBJ_ADD);
}
}
void nfs_netns_sysfs_destroy(struct nfs_net *netns)
{
struct nfs_netns_client *clp = netns->nfs_client;
if (clp) {
kobject_uevent(&clp->kobject, KOBJ_REMOVE);
kobject_del(&clp->kobject);
kobject_put(&clp->kobject);
netns->nfs_client = NULL;
}
}