SUNRPC: pipefs per-net operations helper introduced

During per-net pipes creation and destruction we have to make sure, that pipefs
sb exists for the whole creation/destruction cycle. This is done by using
special mutex which controls pipefs sb reference on network namespace context.
Helper consists of two parts: first of them (rpc_get_dentry_net) searches for
dentry with specified name and returns with mutex taken on success. When pipe
creation or destructions is completed, caller should release this mutex by
rpc_put_dentry_net call.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/include/linux/sunrpc/rpc_pipe_fs.h b/include/linux/sunrpc/rpc_pipe_fs.h
index 2f33822..c13fca3 100644 (file)
--- a/include/linux/sunrpc/rpc_pipe_fs.h
+++ b/include/linux/sunrpc/rpc_pipe_fs.h
@@ -53,6 +53,9 @@ enum {
 
 extern struct dentry *rpc_d_lookup_sb(const struct super_block *sb,
                                      const unsigned char *dir_name);
+extern void rpc_pipefs_init_net(struct net *net);
+extern struct super_block *rpc_get_sb_net(const struct net *net);
+extern void rpc_put_sb_net(const struct net *net);
 
 extern ssize_t rpc_pipe_generic_upcall(struct file *, struct rpc_pipe_msg *,
                                       char __user *, size_t);

diff --git a/net/sunrpc/netns.h b/net/sunrpc/netns.h
index b384252..11d2f48 100644 (file)
--- a/net/sunrpc/netns.h
+++ b/net/sunrpc/netns.h
@@ -11,6 +11,7 @@ struct sunrpc_net {
        struct cache_detail *ip_map_cache;
 
        struct super_block *pipefs_sb;
+       struct mutex pipefs_sb_lock;
 };
 
 extern int sunrpc_net_id;

diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c
index e5e1f35..f075f88 100644 (file)
--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -1023,6 +1023,40 @@ struct dentry *rpc_d_lookup_sb(const struct super_block *sb,
 }
 EXPORT_SYMBOL_GPL(rpc_d_lookup_sb);
 
+void rpc_pipefs_init_net(struct net *net)
+{
+       struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+       mutex_init(&sn->pipefs_sb_lock);
+}
+
+/*
+ * This call will be used for per network namespace operations calls.
+ * Note: Function will be returned with pipefs_sb_lock taken if superblock was
+ * found. This lock have to be released by rpc_put_sb_net() when all operations
+ * will be completed.
+ */
+struct super_block *rpc_get_sb_net(const struct net *net)
+{
+       struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+       mutex_lock(&sn->pipefs_sb_lock);
+       if (sn->pipefs_sb)
+               return sn->pipefs_sb;
+       mutex_unlock(&sn->pipefs_sb_lock);
+       return NULL;
+}
+EXPORT_SYMBOL_GPL(rpc_get_sb_net);
+
+void rpc_put_sb_net(const struct net *net)
+{
+       struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+       BUG_ON(sn->pipefs_sb == NULL);
+       mutex_unlock(&sn->pipefs_sb_lock);
+}
+EXPORT_SYMBOL_GPL(rpc_put_sb_net);
+
 static int
 rpc_fill_super(struct super_block *sb, void *data, int silent)
 {
@@ -1077,7 +1111,9 @@ 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);
 
+       mutex_lock(&sn->pipefs_sb_lock);
        sn->pipefs_sb = NULL;
+       mutex_unlock(&sn->pipefs_sb_lock);
        put_net(net);
        blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
                                           RPC_PIPEFS_UMOUNT,

diff --git a/net/sunrpc/sunrpc_syms.c b/net/sunrpc/sunrpc_syms.c
index 8ec9778..7086d11 100644 (file)
--- a/net/sunrpc/sunrpc_syms.c
+++ b/net/sunrpc/sunrpc_syms.c
@@ -38,6 +38,7 @@ static __net_init int sunrpc_init_net(struct net *net)
        if (err)
                goto err_ipmap;
 
+       rpc_pipefs_init_net(net);
        return 0;
 
 err_ipmap: