LOCKD: Don't call utsname()->nodename from nlmclnt_setlockargs

commit 9a1b6bf818e74bb7aabaecb59492b739f2f4d742 upstream.

Firstly, nlmclnt_setlockargs can be called from a reclaimer thread, in
which case we're in entirely the wrong namespace.

Secondly, commit 8aac62706adaaf0fab02c4327761561c8bda9448 (move
exit_task_namespaces() outside of exit_notify()) now means that
exit_task_work() is called after exit_task_namespaces(), which
triggers an Oops when we're freeing up the locks.

Fix this by ensuring that we initialise the nlm_host's rpc_client at mount
time, so that the cl_nodename field is initialised to the value of
utsname()->nodename that the net namespace uses. Then replace the
lockd callers of utsname()->nodename.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Toralf Förster <toralf.foerster@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Nix <nix@esperi.org.uk>
Cc: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/lockd/clntproc.c b/fs/lockd/clntproc.c
index 9760ecb9b60f..acd394716349 100644
--- a/fs/lockd/clntproc.c
+++ b/fs/lockd/clntproc.c
@@ -125,14 +125,15 @@ static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
 {
         struct nlm_args *argp = &req->a_args;
         struct nlm_lock *lock = &argp->lock;
+        char *nodename = req->a_host->h_rpcclnt->cl_nodename;
 
         nlmclnt_next_cookie(&argp->cookie);
         memcpy(&lock->fh, NFS_FH(file_inode(fl->fl_file)), sizeof(struct nfs_fh));
-        lock->caller  = utsname()->nodename;
+        lock->caller  = nodename;
         lock->oh.data = req->a_owner;
         lock->oh.len  = snprintf(req->a_owner, sizeof(req->a_owner), "%u@%s",
                                 (unsigned int)fl->fl_u.nfs_fl.owner->pid,
-                                utsname()->nodename);
+                                nodename);
         lock->svid = fl->fl_u.nfs_fl.owner->pid;
         lock->fl.fl_start = fl->fl_start;
         lock->fl.fl_end = fl->fl_end;