xprtrdma: On invalidation failure, remove MWs from rl_registered

Callers assume the ro_unmap_sync and ro_unmap_safe methods empty
the list of registered MRs. Ensure that all paths through
fmr_op_unmap_sync() remove MWs from that list.

Fixes: 9d6b0409 ("xprtrdma: Place registered MWs on a ... ")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/xprtrdma/fmr_ops.c

@@ -295,6 +295,7 @@ fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
 	pr_err("rpcrdma: ib_unmap_fmr failed (%i)\n", rc);
 
 	list_for_each_entry_safe(mw, tmp, &req->rl_registered, mw_list) {
+		list_del_init(&mw->mw_list);
 		list_del_init(&mw->fmr.fm_mr->list);
 		fmr_op_recover_mr(mw);
 	}