libceph: enable ceph in a non-default network namespace

Grab a reference on a network namespace of the 'rbd map' (in case of
rbd) or 'mount' (in case of ceph) process and use that to open sockets
instead of always using init_net and bailing if network namespace is
anything but init_net.  Be careful to not share struct ceph_client
instances between different namespaces and don't add any code in the
!CONFIG_NET_NS case.

This is based on a patch from Hong Zhiguo <zhiguohong@tencent.com>.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Sage Weil <sage@redhat.com>

include/linux/ceph/messenger.h

@@ -8,6 +8,7 @@
 #include <linux/radix-tree.h>
 #include <linux/uio.h>
 #include <linux/workqueue.h>
+#include <net/net_namespace.h>
 
 #include <linux/ceph/types.h>
 #include <linux/ceph/buffer.h>
@@ -56,6 +57,7 @@ struct ceph_messenger {
 	struct ceph_entity_addr my_enc_addr;
 
 	atomic_t stopping;
+	possible_net_t net;
 	bool nocrc;
 	bool tcp_nodelay;
 
@@ -267,6 +269,7 @@ extern void ceph_messenger_init(struct ceph_messenger *msgr,
 			u64 required_features,
 			bool nocrc,
 			bool tcp_nodelay);
+extern void ceph_messenger_fini(struct ceph_messenger *msgr);
 
 extern void ceph_con_init(struct ceph_connection *con, void *private,
 			const struct ceph_connection_operations *ops,

net/ceph/ceph_common.c

@@ -9,6 +9,7 @@
 #include <keys/ceph-type.h>
 #include <linux/module.h>
 #include <linux/mount.h>
+#include <linux/nsproxy.h>
 #include <linux/parser.h>
 #include <linux/sched.h>
 #include <linux/seq_file.h>
@@ -16,8 +17,6 @@
 #include <linux/statfs.h>
 #include <linux/string.h>
 #include <linux/vmalloc.h>
-#include <linux/nsproxy.h>
-#include <net/net_namespace.h>
 
 
 #include <linux/ceph/ceph_features.h>
@@ -131,6 +130,13 @@ int ceph_compare_options(struct ceph_options *new_opt,
 	int i;
 	int ret;
 
+	/*
+	 * Don't bother comparing options if network namespaces don't
+	 * match.
+	 */
+	if (!net_eq(current->nsproxy->net_ns, read_pnet(&client->msgr.net)))
+		return -1;
+
 	ret = memcmp(opt1, opt2, ofs);
 	if (ret)
 		return ret;
@@ -335,9 +341,6 @@ ceph_parse_options(char *options, const char *dev_name,
 	int err = -ENOMEM;
 	substring_t argstr[MAX_OPT_ARGS];
 
-	if (current->nsproxy->net_ns != &init_net)
-		return ERR_PTR(-EINVAL);
-
 	opt = kzalloc(sizeof(*opt), GFP_KERNEL);
 	if (!opt)
 		return ERR_PTR(-ENOMEM);
@@ -608,6 +611,7 @@ struct ceph_client *ceph_create_client(struct ceph_options *opt, void *private,
 fail_monc:
 	ceph_monc_stop(&client->monc);
 fail:
+	ceph_messenger_fini(&client->msgr);
 	kfree(client);
 	return ERR_PTR(err);
 }
@@ -621,8 +625,8 @@ void ceph_destroy_client(struct ceph_client *client)
 
 	/* unmount */
 	ceph_osdc_stop(&client->osdc);
-
 	ceph_monc_stop(&client->monc);
+	ceph_messenger_fini(&client->msgr);
 
 	ceph_debugfs_client_cleanup(client);
 

net/ceph/messenger.c

@@ -6,6 +6,7 @@
 #include <linux/inet.h>
 #include <linux/kthread.h>
 #include <linux/net.h>
+#include <linux/nsproxy.h>
 #include <linux/slab.h>
 #include <linux/socket.h>
 #include <linux/string.h>
@@ -479,7 +480,7 @@ static int ceph_tcp_connect(struct ceph_connection *con)
 	int ret;
 
 	BUG_ON(con->sock);
-	ret = sock_create_kern(&init_net, con->peer_addr.in_addr.ss_family,
+	ret = sock_create_kern(read_pnet(&con->msgr->net), paddr->ss_family,
 			       SOCK_STREAM, IPPROTO_TCP, &sock);
 	if (ret)
 		return ret;
@@ -2944,11 +2945,18 @@ void ceph_messenger_init(struct ceph_messenger *msgr,
 	msgr->tcp_nodelay = tcp_nodelay;
 
 	atomic_set(&msgr->stopping, 0);
+	write_pnet(&msgr->net, get_net(current->nsproxy->net_ns));
 
 	dout("%s %p\n", __func__, msgr);
 }
 EXPORT_SYMBOL(ceph_messenger_init);
 
+void ceph_messenger_fini(struct ceph_messenger *msgr)
+{
+	put_net(read_pnet(&msgr->net));
+}
+EXPORT_SYMBOL(ceph_messenger_fini);
+
 static void clear_standby(struct ceph_connection *con)
 {
 	/* come back from STANDBY? */