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authorAndy Adamson <andros@netapp.com>2009-04-03 08:28:48 +0300
committerJ. Bruce Fields <bfields@citi.umich.edu>2009-04-03 17:41:20 -0700
commit496c262cf01106a546ffb7df6fea84b8b881ee19 (patch)
treec1b609cd82d7f64a14eedfc308ce21bdf5b05431
parent6668958fac1d05f55420de702f3678d46c1e93a5 (diff)
nfsd41: check encode size for sessions maxresponse cached
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@netapp.com> [nfsd41: non-page DRC for solo sequence responses] [fixed nfsd4_check_drc_limit cosmetics] Signed-off-by: Benny Halevy <bhalevy@panasas.com> [nfsd41: use cstate session in nfsd4_check_drc_limit] Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
-rw-r--r--fs/nfsd/nfs4xdr.c51
1 files changed, 51 insertions, 0 deletions
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index dd81ac1a1c6c..7fdee828f44e 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(),