From: Andy Adamson <andros@xxxxxxxxxx>
Calculate the space 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 and return
nfserr_rep_too_big_to_cache if the length is too large.
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.
Signed-off-by: Andy Adamson <andros@xxxxxxxxxx>
[nfsd41: non-page DRC for solo sequence responses]
[fixed nfsd4_check_drc_limit cosmetics]
Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
---
fs/nfsd/nfs4xdr.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 58 insertions(+), 0 deletions(-)
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index a2682e8..52ca833 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3089,6 +3089,61 @@ static nfsd4_enc nfsd4_enc_ops[] = {
#endif /* CONFIG_NFSD_V4_1 */
};
+#if defined(CONFIG_NFSD_V4_1)
+/*
+ * 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 = slot->sl_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;
+}
+#else /* CONFIG_NFSD_V4_1 */
+static inline int nfsd4_check_drc_limit(struct nfsd4_compoundres *resp)
+{
+ return 0;
+}
+#endif /* CONFIG_NFSD_V4_1 */
+
void
nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op)
{
@@ -3105,6 +3160,9 @@ 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(),
--
1.6.2.1
--
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