nfs41: back channel drc minimal implementation

For now the back channel ca_maxresponsesize_cached is 0 and there is no
backchannel DRC. Return NFS4ERR_REP_TOO_BIG_TO_CACHE when a cb_sequence
cachethis is true.  When it is false, return NFS4ERR_RETRY_UNCACHED_REP as the
next operation error.

Remember the replay error accross compound operation processing.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 15 insertions, 4 deletions

diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c
index a6f2ded72b17..08b430d922c4 100644
--- a/fs/nfs/callback_xdr.c
+++ b/fs/nfs/callback_xdr.c
@@ -605,7 +605,7 @@ preprocess_nfs4_op(unsigned int op_nr, struct callback_op **op)
 static __be32 process_op(uint32_t minorversion, int nop,
                 struct svc_rqst *rqstp,
                 struct xdr_stream *xdr_in, void *argp,
-                struct xdr_stream *xdr_out, void *resp)
+                struct xdr_stream *xdr_out, void *resp, int* drc_status)
 {
         struct callback_op *op = &callback_ops[0];
         unsigned int op_nr;
@@ -628,6 +628,11 @@ static __be32 process_op(uint32_t minorversion, int nop,
         if (status)
                 goto encode_hdr;
 
+        if (*drc_status) {
+                status = *drc_status;
+                goto encode_hdr;
+        }
+
         maxlen = xdr_out->end - xdr_out->p;
         if (maxlen > 0 && maxlen < PAGE_SIZE) {
                 status = op->decode_args(rqstp, xdr_in, argp);
@@ -636,6 +641,12 @@ static __be32 process_op(uint32_t minorversion, int nop,
         } else
                 status = htonl(NFS4ERR_RESOURCE);
 
+        /* Only set by OP_CB_SEQUENCE processing */
+        if (status == htonl(NFS4ERR_RETRY_UNCACHED_REP)) {
+                *drc_status = status;
+                status = 0;
+        }
+
 encode_hdr:
         res = encode_op_hdr(xdr_out, op_nr, status);
         if (unlikely(res))
@@ -655,7 +666,7 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r
         struct cb_compound_hdr_res hdr_res = { NULL };
         struct xdr_stream xdr_in, xdr_out;
         __be32 *p;
-        __be32 status;
+        __be32 status, drc_status = 0;
         unsigned int nops = 0;
 
         dprintk("%s: start\n", __func__);
@@ -675,8 +686,8 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r
                 return rpc_system_err;
 
         while (status == 0 && nops != hdr_arg.nops) {
-                status = process_op(hdr_arg.minorversion, nops,
-                                    rqstp, &xdr_in, argp, &xdr_out, resp);
+                status = process_op(hdr_arg.minorversion, nops, rqstp,
+                                    &xdr_in, argp, &xdr_out, resp, &drc_status);
                 nops++;
         }