[Devel] [RFC PATCH 4/5] SUNRPC: put pipefs superblock link on network namespace

[Stanislav Kinsbursky]

We have modules (like, pNFS blocklayout module) which creates pipes on
rpc_pipefs. Thus we need per-net operations for them. To make it possible to
create piepes in per-net operations, we require super block. So we have to put
sb link on network namespace context. Note, that dont't hardly require to
create pipes in per-net operations. IOW, if pipefs wan't mounted yet, that no
sb link reference will peresent on network namespace. In this case we just
passing through pipe
creation. The pipe will be created druing pipefs mount notification.

Signed-off-by: Stanislav Kinsbursky <skinsbursky at parallels.com>

---
 net/sunrpc/netns.h    |    2 ++
 net/sunrpc/rpc_pipe.c |    4 ++++
 2 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/net/sunrpc/netns.h b/net/sunrpc/netns.h
index d013bf2..b384252 100644
--- a/net/sunrpc/netns.h
+++ b/net/sunrpc/netns.h
@@ -9,6 +9,8 @@ struct cache_detail;
 struct sunrpc_net {
 	struct proc_dir_entry *proc_net_rpc;
 	struct cache_detail *ip_map_cache;
+
+	struct super_block *pipefs_sb;
 };
 
 extern int sunrpc_net_id;
diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c
index a8a8812..a873f03 100644
--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -1039,6 +1039,7 @@ rpc_fill_super(struct super_block *sb, void *data, int silent)
 	struct inode *inode;
 	struct dentry *root;
 	struct net *net = current->nsproxy->net_ns;
+	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
 	int err;
 
 	sb->s_blocksize = PAGE_CACHE_SIZE;
@@ -1063,6 +1064,7 @@ rpc_fill_super(struct super_block *sb, void *data, int silent)
 	if (err)
 		goto err_depopulate;
 	sb->s_fs_info = get_net(net);
+	sn->pipefs_sb = sb;
 	return 0;
 
 err_depopulate:
@@ -1081,7 +1083,9 @@ rpc_mount(struct file_system_type *fs_type,
 void rpc_kill_sb(struct super_block *sb)
 {
 	struct net *net = sb->s_fs_info;
+	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
 
+	sn->pipefs_sb = NULL;
 	put_net(net);
 	blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
 					   RPC_PIPEFS_UMOUNT,