nfsd41: try to check reply size before operation
For checking the size of reply before calling a operation,
we need try to get maxsize of the operation's reply.
v3: using new method as Bruce said,
"we could handle operations in two different ways:
- For operations that actually change something (write, rename,
open, close, ...), do it the way we're doing it now: be
very careful to estimate the size of the response before even
processing the operation.
- For operations that don't change anything (read, getattr, ...)
just go ahead and do the operation. If you realize after the
fact that the response is too large, then return the error at
that point.
So we'd add another flag to op_flags: say, OP_MODIFIES_SOMETHING. And for
operations with OP_MODIFIES_SOMETHING set, we'd do the first thing. For
operations without it set, we'd do the second."
Signed-off-by: Mi Jinlong <mijinlong@cn.fujitsu.com>
[bfields@redhat.com: crash, don't attempt to handle, undefined op_rsize_bop]
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 5252d66..f4116cf 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3387,34 +3387,29 @@
/*
* Calculate the total amount of memory that the compound response has taken
- * after encoding the current operation.
+ * after encoding the current operation with pad.
*
- * 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.
+ * pad: if operation is non-idempotent, pad was calculate by op_rsize_bop()
+ * which was specified at nfsd4_operation, else pad is zero.
*
- * Compare this length to the session se_fmaxresp_cached.
+ * Compare this length to the session se_fmaxresp_sz and 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 nfsd4_check_resp_size(struct nfsd4_compoundres *resp, u32 pad)
{
- 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;
+ u32 length, tlen = 0;
if (!nfsd4_has_session(&resp->cstate))
- return status;
+ return 0;
session = resp->cstate.session;
- if (session == NULL || slot->sl_cachethis == 0)
- return status;
-
- if (resp->opcnt >= args->opcnt)
- pad = 0; /* this is the last operation */
+ if (session == NULL)
+ return 0;
if (xb->page_len == 0) {
length = (char *)resp->p - (char *)xb->head[0].iov_base + pad;
@@ -3427,10 +3422,14 @@
dprintk("%s length %u, xb->page_len %u tlen %u pad %u\n", __func__,
length, xb->page_len, tlen, pad);
- if (length <= session->se_fchannel.maxresp_cached)
- return status;
- else
+ if (length > session->se_fchannel.maxresp_sz)
+ return nfserr_rep_too_big;
+
+ if (slot->sl_cachethis == 1 &&
+ length > session->se_fchannel.maxresp_cached)
return nfserr_rep_too_big_to_cache;
+
+ return 0;
}
void
@@ -3450,8 +3449,8 @@
!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;
+ if (!op->status)
+ op->status = nfsd4_check_resp_size(resp, 0);
status:
/*
* Note: We write the status directly, instead of using WRITE32(),