[PATCH] NFSv4.1: handle memory allocation failure in nfs4_schedule_state_manager()

[ChenXiaoSong]

If memory allocation fail in nfs4_schedule_state_manager() when mount
NFSv4.1/NFSv4.2, nfs4_run_state_manager() will not be called, and current
construction state will never be marked as ready or failed,
nfs_wait_client_init_complete() will wait forever, as shown below:

  syscall(mount)
  ...
    nfs4_init_client
      nfs4_discover_server_trunking
        nfs41_discover_server_trunking
          nfs4_schedule_state_manager
            kthread_run /* nfs4_run_state_manager() will not be called */
              kthread_create
                kthread_create_on_node
                  __kthread_create_on_node
                    create = kmalloc() = NULL
                    return ERR_PTR(-ENOMEM)
          nfs_wait_client_init_complete /* wait forever */

Fix this by checking return value of nfs4_schedule_state_manager() which
can indicate whether kernel thread is created successful.

Signed-off-by: ChenXiaoSong <chenxiaosong2@xxxxxxxxxx>
---
 fs/nfs/nfs4_fs.h   |  2 +-
 fs/nfs/nfs4state.c | 15 ++++++++++-----
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index cfef738d765e..74c6d1504010 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -502,7 +502,7 @@ extern int nfs4_state_mark_reclaim_nograce(struct nfs_client *, struct nfs4_stat
 extern void nfs4_schedule_lease_recovery(struct nfs_client *);
 extern int nfs4_wait_clnt_recover(struct nfs_client *clp);
 extern int nfs4_client_recover_expired_lease(struct nfs_client *clp);
-extern void nfs4_schedule_state_manager(struct nfs_client *);
+extern int nfs4_schedule_state_manager(struct nfs_client *);
 extern void nfs4_schedule_path_down_recovery(struct nfs_client *clp);
 extern int nfs4_schedule_stateid_recovery(const struct nfs_server *, struct nfs4_state *);
 extern int nfs4_schedule_migration_recovery(const struct nfs_server *);
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index a2d2d5d1b088..127027f777c8 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -376,8 +376,9 @@ int nfs41_discover_server_trunking(struct nfs_client *clp,
 		else
 			set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
 	}
-	nfs4_schedule_state_manager(clp);
-	status = nfs_wait_client_init_complete(clp);
+	status = nfs4_schedule_state_manager(clp);
+	if (!status)
+		status = nfs_wait_client_init_complete(clp);
 	if (status < 0)
 		nfs_put_client(clp);
 	return status;
@@ -1201,11 +1202,12 @@ static void nfs4_clear_state_manager_bit(struct nfs_client *clp)
 /*
  * Schedule the nfs_client asynchronous state management routine
  */
-void nfs4_schedule_state_manager(struct nfs_client *clp)
+int nfs4_schedule_state_manager(struct nfs_client *clp)
 {
 	struct task_struct *task;
 	char buf[INET6_ADDRSTRLEN + sizeof("-manager") + 1];
 	struct rpc_clnt *cl = clp->cl_rpcclient;
+	int ret = 0;
 
 	while (cl != cl->cl_parent)
 		cl = cl->cl_parent;
@@ -1213,7 +1215,7 @@ void nfs4_schedule_state_manager(struct nfs_client *clp)
 	set_bit(NFS4CLNT_RUN_MANAGER, &clp->cl_state);
 	if (test_and_set_bit(NFS4CLNT_MANAGER_AVAILABLE, &clp->cl_state) != 0) {
 		wake_up_var(&clp->cl_state);
-		return;
+		goto out;
 	}
 	set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state);
 	__module_get(THIS_MODULE);
@@ -1228,13 +1230,16 @@ void nfs4_schedule_state_manager(struct nfs_client *clp)
 	rcu_read_unlock();
 	task = kthread_run(nfs4_run_state_manager, clp, "%s", buf);
 	if (IS_ERR(task)) {
+		ret = PTR_ERR(task);
 		printk(KERN_ERR "%s: kthread_run: %ld\n",
-			__func__, PTR_ERR(task));
+			__func__, ret);
 		nfs4_clear_state_manager_bit(clp);
 		clear_bit(NFS4CLNT_MANAGER_AVAILABLE, &clp->cl_state);
 		nfs_put_client(clp);
 		module_put(THIS_MODULE);
 	}
+out:
+	return ret;
 }
 
 /*
-- 
2.31.1