fs: track fl_owner for leases

Just like for other lock types we should allow different owners to have
a read lease on a file.  Currently this can't happen, but with the addition
of pNFS layout leases we'll need this feature.

Signed-off-by: Christoph Hellwig <hch@lst.de>

fs/nfsd/nfs4state.c

@@ -683,7 +683,7 @@ static void nfs4_put_deleg_lease(struct nfs4_file *fp)
 	spin_unlock(&fp->fi_lock);
 
 	if (filp) {
-		vfs_setlease(filp, F_UNLCK, NULL, NULL);
+		vfs_setlease(filp, F_UNLCK, NULL, (void **)&fp);
 		fput(filp);
 	}
 }