NLM: Fix Oops in nlmclnt_mark_reclaim()

 When mixing -olock and -onolock mounts on the same client, we have to
 check that fl->fl_u.nfs_fl.owner is set before dereferencing it.

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/lockd/clntlock.c

@@ -157,6 +157,8 @@ void nlmclnt_mark_reclaim(struct nlm_host *host)
 		inode = fl->fl_file->f_dentry->d_inode;
 		if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
 			continue;
+		if (fl->fl_u.nfs_fl.owner == NULL)
+			continue;
 		if (fl->fl_u.nfs_fl.owner->host != host)
 			continue;
 		if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_GRANTED))
@@ -226,6 +228,8 @@ restart:
 		inode = fl->fl_file->f_dentry->d_inode;
 		if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
 			continue;
+		if (fl->fl_u.nfs_fl.owner == NULL)
+			continue;
 		if (fl->fl_u.nfs_fl.owner->host != host)
 			continue;
 		if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_RECLAIM))