diff options
| -rw-r--r-- | fs/nfsd/nfs4xdr.c | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index dd81ac1a1c6..7fdee828f44 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -3078,6 +3078,54 @@ static nfsd4_enc nfsd4_enc_ops[] = { [OP_RECLAIM_COMPLETE] = (nfsd4_enc)nfsd4_encode_noop, }; +/* + * Calculate the total amount of memory that the compound response has taken + * after encoding the current operation. + * + * pad: add on 8 bytes for the next operation's op_code and status so that + * there is room to cache a failure on the next operation. + * + * Compare this length to the session se_fmaxresp_cached. + * + * Our se_fmaxresp_cached will always be a multiple of PAGE_SIZE, and so + * will be at least a page and will therefore hold the xdr_buf head. + */ +static int nfsd4_check_drc_limit(struct nfsd4_compoundres *resp) +{ + int status = 0; + struct xdr_buf *xb = &resp->rqstp->rq_res; + struct nfsd4_compoundargs *args = resp->rqstp->rq_argp; + struct nfsd4_session *session = NULL; + struct nfsd4_slot *slot = resp->cstate.slot; + u32 length, tlen = 0, pad = 8; + + if (!nfsd4_has_session(&resp->cstate)) + return status; + + session = resp->cstate.session; + if (session == NULL || slot->sl_cache_entry.ce_cachethis == 0) + return status; + + if (resp->opcnt >= args->opcnt) + pad = 0; /* this is the last operation */ + + if (xb->page_len == 0) { + length = (char *)resp->p - (char *)xb->head[0].iov_base + pad; + } else { + if (xb->tail[0].iov_base && xb->tail[0].iov_len > 0) + tlen = (char *)resp->p - (char *)xb->tail[0].iov_base; + + length = xb->head[0].iov_len + xb->page_len + tlen + pad; + } + dprintk("%s length %u, xb->page_len %u tlen %u pad %u\n", __func__, + length, xb->page_len, tlen, pad); + + if (length <= session->se_fmaxresp_cached) + return status; + else + return nfserr_rep_too_big_to_cache; +} + void nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op) { @@ -3094,6 +3142,9 @@ nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op) BUG_ON(op->opnum < 0 || op->opnum >= ARRAY_SIZE(nfsd4_enc_ops) || !nfsd4_enc_ops[op->opnum]); op->status = nfsd4_enc_ops[op->opnum](resp, op->status, &op->u); + /* nfsd4_check_drc_limit guarantees enough room for error status */ + if (!op->status && nfsd4_check_drc_limit(resp)) + op->status = nfserr_rep_too_big_to_cache; status: /* * Note: We write the status directly, instead of using WRITE32(), |