--- fs/nfsd/nfs4state.c

+++ fs/nfsd/nfs4state.c

@@ -2002,7 +2002,9 @@ nfs4_file_downgrade(struct file *filp, u

{

if (share_access & NFS4_SHARE_ACCESS_WRITE) {

drop_file_write_access(filp);

+ spin_lock(&filp->f_lock);

filp->f_mode = (filp->f_mode | FMODE_READ) & ~FMODE_WRITE;

+ spin_unlock(&filp->f_lock);

}

}