[PATCH] libceph: allow custom network namespaces

[Hong Zhiguo <honkiko@gmail.com>]

in current implementaion init_net is always used.

But in most cases, if user do a rbd map or ceph mount in
a container, it's expected to use the container network namespace.

This patch saves the container's netns in ceph_options on a rbd map
or ceph mount. And use the netns other than init_net when creating
socket. Ref count of the netns is only taken by the ceph_options
in ceph_client since lifetime of osds and mon is within that of
ceph_client.

I've tested this patch in docker container with below operations:
- rbd map
- write/read on the rbd
- rbd unmap

Signed-off-by: Hong Zhiguo <zhiguohong@tencent.com>
---
 fs/ceph/mds_client.c           | 3 ++-
 include/linux/ceph/libceph.h   | 3 +++
 include/linux/ceph/messenger.h | 4 +++-
 net/ceph/ceph_common.c         | 7 ++++---
 net/ceph/messenger.c           | 8 +++++++-
 net/ceph/mon_client.c          | 2 +-
 net/ceph/osd_client.c          | 3 ++-
 7 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 8080d48..3fb0976 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -440,7 +440,8 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
 	s->s_seq = 0;
 	mutex_init(&s->s_mutex);
 
-	ceph_con_init(&s->s_con, s, &mds_con_ops, &mdsc->fsc->client->msgr);
+	ceph_con_init(&s->s_con, s, &mds_con_ops, &mdsc->fsc->client->msgr,
+			mdsc->fsc->client->options->netns);
 
 	spin_lock_init(&s->s_gen_ttl_lock);
 	s->s_cap_gen = 0;
diff --git a/include/linux/ceph/libceph.h b/include/linux/ceph/libceph.h
index d73a569..442d9f3 100644
--- a/include/linux/ceph/libceph.h
+++ b/include/linux/ceph/libceph.h
@@ -22,6 +22,8 @@
 #include <linux/ceph/osd_client.h>
 #include <linux/ceph/ceph_fs.h>
 
+struct net;
+
 /*
  * mount options
  */
@@ -46,6 +48,7 @@ struct ceph_options {
 	unsigned long mount_timeout;		/* jiffies */
 	unsigned long osd_idle_ttl;		/* jiffies */
 	unsigned long osd_keepalive_timeout;	/* jiffies */
+	struct net *netns;
 
 	/*
 	 * any type that can't be simply compared or doesn't need need
diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
index e154994..3b0a314 100644
--- a/include/linux/ceph/messenger.h
+++ b/include/linux/ceph/messenger.h
@@ -14,6 +14,7 @@
 
 struct ceph_msg;
 struct ceph_connection;
+struct net;
 
 /*
  * Ceph defines these callbacks for handling connection events.
@@ -189,6 +190,7 @@ struct ceph_connection {
 	struct ceph_messenger *msgr;
 
 	atomic_t sock_state;
+	struct net *netns;
 	struct socket *sock;
 	struct ceph_entity_addr peer_addr; /* peer address */
 	struct ceph_entity_addr peer_addr_for_me;
@@ -270,7 +272,7 @@ extern void ceph_messenger_init(struct ceph_messenger *msgr,
 
 extern void ceph_con_init(struct ceph_connection *con, void *private,
 			const struct ceph_connection_operations *ops,
-			struct ceph_messenger *msgr);
+			struct ceph_messenger *msgr, struct net *netns);
 extern void ceph_con_open(struct ceph_connection *con,
 			  __u8 entity_type, __u64 entity_num,
 			  struct ceph_entity_addr *addr);
diff --git a/net/ceph/ceph_common.c b/net/ceph/ceph_common.c
index 925d0c8..1c42d96 100644
--- a/net/ceph/ceph_common.c
+++ b/net/ceph/ceph_common.c
@@ -269,6 +269,9 @@ static match_table_t opt_tokens = {
 void ceph_destroy_options(struct ceph_options *opt)
 {
 	dout("destroy_options %p\n", opt);
+	if (opt->netns) {
+		put_net(opt->netns);
+	}
 	kfree(opt->name);
 	if (opt->key) {
 		ceph_crypto_key_destroy(opt->key);
@@ -335,9 +338,6 @@ 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);
@@ -501,6 +501,7 @@ ceph_parse_options(char *options, const char *dev_name,
 	}
 
 	/* success */
+	opt->netns = get_net(current->nsproxy->net_ns);
 	return opt;
 
 out:
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 967080a..43ec07d 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -736,7 +736,7 @@ bool ceph_con_opened(struct ceph_connection *con)
  */
 void ceph_con_init(struct ceph_connection *con, void *private,
 	const struct ceph_connection_operations *ops,
-	struct ceph_messenger *msgr)
+	struct ceph_messenger *msgr, struct net *netns)
 {
 	dout("con_init %p\n", con);
 	memset(con, 0, sizeof(*con));
@@ -744,6 +744,12 @@ void ceph_con_init(struct ceph_connection *con, void *private,
 	con->ops = ops;
 	con->msgr = msgr;
 
+	/*
+	 * don't take extra refcnt of netns here since both mon and osds
+	 * have lifetime within that of ceph_client
+	 */
+	con->netns = netns;
+
 	con_sock_state_init(con);
 
 	mutex_init(&con->mutex);
diff --git a/net/ceph/mon_client.c b/net/ceph/mon_client.c
index 9d6ff12..04128af 100644
--- a/net/ceph/mon_client.c
+++ b/net/ceph/mon_client.c
@@ -832,7 +832,7 @@ int ceph_monc_init(struct ceph_mon_client *monc, struct ceph_client *cl)
 		goto out_auth_reply;
 
 	ceph_con_init(&monc->con, monc, &mon_con_ops,
-		      &monc->client->msgr);
+		      &monc->client->msgr, monc->client->options->netns);
 
 	monc->cur_mon = -1;
 	monc->hunting = true;
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 5003367..32d9fa9 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -1022,7 +1022,8 @@ static struct ceph_osd *create_osd(struct ceph_osd_client *osdc, int onum)
 	INIT_LIST_HEAD(&osd->o_osd_lru);
 	osd->o_incarnation = 1;
 
-	ceph_con_init(&osd->o_con, osd, &osd_con_ops, &osdc->client->msgr);
+	ceph_con_init(&osd->o_con, osd, &osd_con_ops, &osdc->client->msgr,
+			osdc->client->options->netns);
 
 	INIT_LIST_HEAD(&osd->o_keepalive_item);
 	return osd;
-- 
1.9.1