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Commit 756b9b37 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

SUNRPC: Fix callback channel 



The NFSv4.1 callback channel is currently broken because the receive
message will keep shrinking because the backchannel receive buffer size
never gets reset.
The easiest solution to this problem is instead of changing the receive
buffer, to rather adjust the copied request.

Fixes: 38b7631f ("nfs4: limit callback decoding to received bytes")
Cc: Benjamin Coddington <bcodding@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent 527e9316

fs/nfs/callback_xdr.c

+2 −5
Original line number Diff line number Diff line
@@ -78,8 +78,7 @@ static __be32 *read_buf(struct xdr_stream *xdr, int nbytes) 


	p = xdr_inline_decode(xdr, nbytes);

	if (unlikely(p == NULL))

		printk(KERN_WARNING "NFS: NFSv4 callback reply buffer overflowed "

							"or truncated request.\n");

		printk(KERN_WARNING "NFS: NFSv4 callback reply buffer overflowed!\n");

	return p;

}
@@ -890,7 +889,6 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r 
	struct cb_compound_hdr_arg hdr_arg = { 0 };

	struct cb_compound_hdr_res hdr_res = { NULL };

	struct xdr_stream xdr_in, xdr_out;

	struct xdr_buf *rq_arg = &rqstp->rq_arg;

	__be32 *p, status;

	struct cb_process_state cps = {

		.drc_status = 0,
@@ -902,8 +900,7 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r 


	dprintk("%s: start\n", __func__);



	rq_arg->len = rq_arg->head[0].iov_len + rq_arg->page_len;

	xdr_init_decode(&xdr_in, rq_arg, rq_arg->head[0].iov_base);

	xdr_init_decode(&xdr_in, &rqstp->rq_arg, rqstp->rq_arg.head[0].iov_base);



	p = (__be32*)((char *)rqstp->rq_res.head[0].iov_base + rqstp->rq_res.head[0].iov_len);

	xdr_init_encode(&xdr_out, &rqstp->rq_res, p);

net/sunrpc/backchannel_rqst.c

+0 −8
Original line number Diff line number Diff line
@@ -353,20 +353,12 @@ void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied) 
{

	struct rpc_xprt *xprt = req->rq_xprt;

	struct svc_serv *bc_serv = xprt->bc_serv;

	struct xdr_buf *rq_rcv_buf = &req->rq_rcv_buf;



	spin_lock(&xprt->bc_pa_lock);

	list_del(&req->rq_bc_pa_list);

	xprt_dec_alloc_count(xprt, 1);

	spin_unlock(&xprt->bc_pa_lock);



	if (copied <= rq_rcv_buf->head[0].iov_len) {

		rq_rcv_buf->head[0].iov_len = copied;

		rq_rcv_buf->page_len = 0;

	} else {

		rq_rcv_buf->page_len = copied - rq_rcv_buf->head[0].iov_len;

	}



	req->rq_private_buf.len = copied;

	set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);

net/sunrpc/svc.c

+12 −0
Original line number Diff line number Diff line
@@ -1363,7 +1363,19 @@ bc_svc_process(struct svc_serv *serv, struct rpc_rqst *req, 
	memcpy(&rqstp->rq_addr, &req->rq_xprt->addr, rqstp->rq_addrlen);

	memcpy(&rqstp->rq_arg, &req->rq_rcv_buf, sizeof(rqstp->rq_arg));

	memcpy(&rqstp->rq_res, &req->rq_snd_buf, sizeof(rqstp->rq_res));



	/* Adjust the argument buffer length */

	rqstp->rq_arg.len = req->rq_private_buf.len;

	if (rqstp->rq_arg.len <= rqstp->rq_arg.head[0].iov_len) {

		rqstp->rq_arg.head[0].iov_len = rqstp->rq_arg.len;

		rqstp->rq_arg.page_len = 0;

	} else if (rqstp->rq_arg.len <= rqstp->rq_arg.head[0].iov_len +

			rqstp->rq_arg.page_len)

		rqstp->rq_arg.page_len = rqstp->rq_arg.len -

			rqstp->rq_arg.head[0].iov_len;

	else

		rqstp->rq_arg.len = rqstp->rq_arg.head[0].iov_len +

			rqstp->rq_arg.page_len;



	/* reset result send buffer "put" position */

	resv->iov_len = 0;