[PATCH] SUNRPC: Give cloned RPC clients their own rpc_pipefs directory

This patch fixes a regression in 2.6.19 in which the use of multiple
krb5 mounts against the same NFS server may result in an Oops on
unmount. The Oops is due to the fact that multiple NFS krb5 clients may
end up inadvertently sharing the same rpc_pipefs upcall pipe. The first
client to 'umount' will unlink that shared pipe, causing an Oops.

The solution is to give each client their own upcall pipe. This fix has
been in mainline since 2.6.20-rc1.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
[chrisw: backport to 2.6.19.2]
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

include/linux/sunrpc/clnt.h

@@ -53,6 +53,7 @@ struct rpc_clnt {
 	struct dentry *		cl_dentry;	/* inode */
 	struct rpc_clnt *	cl_parent;	/* Points to parent of clones */
 	struct rpc_rtt		cl_rtt_default;
+	struct rpc_program *	cl_program;
 	char			cl_inline_name[32];
 };
 

net/sunrpc/clnt.c

@@ -141,6 +141,7 @@ static struct rpc_clnt * rpc_new_client(struct rpc_xprt *xprt, char *servname, s
 	clnt->cl_vers     = version->number;
 	clnt->cl_stats    = program->stats;
 	clnt->cl_metrics  = rpc_alloc_iostats(clnt);
+	clnt->cl_program  = program;
 
 	if (!xprt_bound(clnt->cl_xprt))
 		clnt->cl_autobind = 1;
@@ -252,6 +253,7 @@ struct rpc_clnt *
 rpc_clone_client(struct rpc_clnt *clnt)
 {
 	struct rpc_clnt *new;
+	int err = -ENOMEM;
 
 	new = kmalloc(sizeof(*new), GFP_KERNEL);
 	if (!new)
@@ -259,6 +261,10 @@ rpc_clone_client(struct rpc_clnt *clnt)
 	memcpy(new, clnt, sizeof(*new));
 	atomic_set(&new->cl_count, 1);
 	atomic_set(&new->cl_users, 0);
+	new->cl_metrics = rpc_alloc_iostats(clnt);
+	err = rpc_setup_pipedir(new, clnt->cl_program->pipe_dir_name);
+	if (err != 0)
+		goto out_no_path;
 	new->cl_parent = clnt;
 	atomic_inc(&clnt->cl_count);
 	new->cl_xprt = xprt_get(clnt->cl_xprt);
@@ -266,16 +272,16 @@ rpc_clone_client(struct rpc_clnt *clnt)
 	new->cl_autobind = 0;
 	new->cl_oneshot = 0;
 	new->cl_dead = 0;
-	if (!IS_ERR(new->cl_dentry))
-		dget(new->cl_dentry);
 	rpc_init_rtt(&new->cl_rtt_default, clnt->cl_xprt->timeout.to_initval);
 	if (new->cl_auth)
 		atomic_inc(&new->cl_auth->au_count);
-	new->cl_metrics = rpc_alloc_iostats(clnt);
 	return new;
+out_no_path:
+	rpc_free_iostats(new->cl_metrics);
+	kfree(new);
 out_no_clnt:
-	printk(KERN_INFO "RPC: out of memory in %s\n", __FUNCTION__);
-	return ERR_PTR(-ENOMEM);
+	dprintk("RPC: %s returned error %d\n", __FUNCTION__, err);
+	return ERR_PTR(err);
 }
 
 /*
@@ -328,16 +334,14 @@ rpc_destroy_client(struct rpc_clnt *clnt)
 		rpcauth_destroy(clnt->cl_auth);
 		clnt->cl_auth = NULL;
 	}
-	if (clnt->cl_parent != clnt) {
-		if (!IS_ERR(clnt->cl_dentry))
-			dput(clnt->cl_dentry);
-		rpc_destroy_client(clnt->cl_parent);
-		goto out_free;
-	}
 	if (!IS_ERR(clnt->cl_dentry)) {
 		rpc_rmdir(clnt->cl_dentry);
 		rpc_put_mount();
 	}
+	if (clnt->cl_parent != clnt) {
+		rpc_destroy_client(clnt->cl_parent);
+		goto out_free;
+	}
 	if (clnt->cl_server != clnt->cl_inline_name)
 		kfree(clnt->cl_server);
 out_free: