NFS client bugfixes for Linux 3.9

- Stable fix for memory corruption issues in nfs4[01]_walk_client_list
 - Stable fix for an Oopsable bug in rpc_clone_client
 - Another state manager deadlock in the NFSv4 open code
 - Memory leaks in nfs4_discover_server_trunking and rpc_new_client
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Merge tag 'nfs-for-3.9-4' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client bugfixes from Trond Myklebust:
 - fix for memory corruption issues in nfs4[01]_walk_client_list (stable)
 - fix for an Oopsable bug in rpc_clone_client (stable)
 - another state manager deadlock in the NFSv4 open code
 - memory leaks in nfs4_discover_server_trunking and rpc_new_client

* tag 'nfs-for-3.9-4' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  NFSv4: Fix another potential state manager deadlock
  SUNRPC: Fix a potential memory leak in rpc_new_client
  NFSv4/4.1: Fix bugs in nfs4[01]_walk_client_list
  NFSv4: Fix a memory leak in nfs4_discover_server_trunking
  SUNRPC: Remove extra xprt_put()

fs/nfs/nfs4client.c

@@ -300,7 +300,7 @@ int nfs40_walk_client_list(struct nfs_client *new,
 			   struct rpc_cred *cred)
 {
 	struct nfs_net *nn = net_generic(new->cl_net, nfs_net_id);
-	struct nfs_client *pos, *n, *prev = NULL;
+	struct nfs_client *pos, *prev = NULL;
 	struct nfs4_setclientid_res clid = {
 		.clientid	= new->cl_clientid,
 		.confirm	= new->cl_confirm,
@@ -308,10 +308,23 @@ int nfs40_walk_client_list(struct nfs_client *new,
 	int status = -NFS4ERR_STALE_CLIENTID;
 
 	spin_lock(&nn->nfs_client_lock);
-	list_for_each_entry_safe(pos, n, &nn->nfs_client_list, cl_share_link) {
+	list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
 		/* If "pos" isn't marked ready, we can't trust the
 		 * remaining fields in "pos" */
-		if (pos->cl_cons_state < NFS_CS_READY)
+		if (pos->cl_cons_state > NFS_CS_READY) {
+			atomic_inc(&pos->cl_count);
+			spin_unlock(&nn->nfs_client_lock);
+
+			if (prev)
+				nfs_put_client(prev);
+			prev = pos;
+
+			status = nfs_wait_client_init_complete(pos);
+			spin_lock(&nn->nfs_client_lock);
+			if (status < 0)
+				continue;
+		}
+		if (pos->cl_cons_state != NFS_CS_READY)
 			continue;
 
 		if (pos->rpc_ops != new->rpc_ops)
@@ -423,16 +436,16 @@ int nfs41_walk_client_list(struct nfs_client *new,
 			   struct rpc_cred *cred)
 {
 	struct nfs_net *nn = net_generic(new->cl_net, nfs_net_id);
-	struct nfs_client *pos, *n, *prev = NULL;
+	struct nfs_client *pos, *prev = NULL;
 	int status = -NFS4ERR_STALE_CLIENTID;
 
 	spin_lock(&nn->nfs_client_lock);
-	list_for_each_entry_safe(pos, n, &nn->nfs_client_list, cl_share_link) {
+	list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
 		/* If "pos" isn't marked ready, we can't trust the
 		 * remaining fields in "pos", especially the client
 		 * ID and serverowner fields.  Wait for CREATE_SESSION
 		 * to finish. */
-		if (pos->cl_cons_state < NFS_CS_READY) {
+		if (pos->cl_cons_state > NFS_CS_READY) {
 			atomic_inc(&pos->cl_count);
 			spin_unlock(&nn->nfs_client_lock);
 
@@ -440,18 +453,17 @@ int nfs41_walk_client_list(struct nfs_client *new,
 				nfs_put_client(prev);
 			prev = pos;
 
-			nfs4_schedule_lease_recovery(pos);
 			status = nfs_wait_client_init_complete(pos);
-			if (status < 0) {
-				nfs_put_client(pos);
-				spin_lock(&nn->nfs_client_lock);
-				continue;
+			if (status == 0) {
+				nfs4_schedule_lease_recovery(pos);
+				status = nfs4_wait_clnt_recover(pos);
 			}
-			status = pos->cl_cons_state;
 			spin_lock(&nn->nfs_client_lock);
 			if (status < 0)
 				continue;
 		}
+		if (pos->cl_cons_state != NFS_CS_READY)
+			continue;
 
 		if (pos->rpc_ops != new->rpc_ops)
 			continue;
@@ -469,17 +481,17 @@ int nfs41_walk_client_list(struct nfs_client *new,
 			continue;
 
 		atomic_inc(&pos->cl_count);
-		spin_unlock(&nn->nfs_client_lock);
+		*result = pos;
 		dprintk("NFS: <-- %s using nfs_client = %p ({%d})\n",
 			__func__, pos, atomic_read(&pos->cl_count));
-
-		*result = pos;
-		return 0;
+		break;
 	}
 
 	/* No matching nfs_client found. */
 	spin_unlock(&nn->nfs_client_lock);
 	dprintk("NFS: <-- %s status = %d\n", __func__, status);
+	if (prev)
+		nfs_put_client(prev);
 	return status;
 }
 #endif	/* CONFIG_NFS_V4_1 */

fs/nfs/nfs4proc.c

@@ -1046,6 +1046,7 @@ static struct nfs4_state *nfs4_try_open_cached(struct nfs4_opendata *opendata)
 		/* Save the delegation */
 		nfs4_stateid_copy(&stateid, &delegation->stateid);
 		rcu_read_unlock();
+		nfs_release_seqid(opendata->o_arg.seqid);
 		ret = nfs_may_open(state->inode, state->owner->so_cred, open_mode);
 		if (ret != 0)
 			goto out;

fs/nfs/nfs4state.c

@@ -1886,7 +1886,13 @@ again:
 			status = PTR_ERR(clnt);
 			break;
 		}
-		clp->cl_rpcclient = clnt;
+		/* Note: this is safe because we haven't yet marked the
+		 * client as ready, so we are the only user of
+		 * clp->cl_rpcclient
+		 */
+		clnt = xchg(&clp->cl_rpcclient, clnt);
+		rpc_shutdown_client(clnt);
+		clnt = clp->cl_rpcclient;
 		goto again;
 
 	case -NFS4ERR_MINOR_VERS_MISMATCH:

net/sunrpc/clnt.c

@@ -304,10 +304,8 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru
 	err = rpciod_up();
 	if (err)
 		goto out_no_rpciod;
-	err = -EINVAL;
-	if (!xprt)
-		goto out_no_xprt;
 
+	err = -EINVAL;
 	if (args->version >= program->nrvers)
 		goto out_err;
 	version = program->version[args->version];
@@ -382,10 +380,9 @@ out_no_principal:
 out_no_stats:
 	kfree(clnt);
 out_err:
-	xprt_put(xprt);
-out_no_xprt:
 	rpciod_down();
 out_no_rpciod:
+	xprt_put(xprt);
 	return ERR_PTR(err);
 }
 
@@ -512,7 +509,7 @@ static struct rpc_clnt *__rpc_clone_client(struct rpc_create_args *args,
 	new = rpc_new_client(args, xprt);
 	if (IS_ERR(new)) {
 		err = PTR_ERR(new);
-		goto out_put;
+		goto out_err;
 	}
 
 	atomic_inc(&clnt->cl_count);
@@ -525,8 +522,6 @@ static struct rpc_clnt *__rpc_clone_client(struct rpc_create_args *args,
 	new->cl_chatty = clnt->cl_chatty;
 	return new;
 
-out_put:
-	xprt_put(xprt);
 out_err:
 	dprintk("RPC:       %s: returned error %d\n", __func__, err);
 	return ERR_PTR(err);