SUNRPC: Prepare for xdr_stream-style decoding on the server-side

A "permanent" struct xdr_stream is allocated in struct svc_rqst so
that it is usable by all server-side decoders. A per-rqst scratch
buffer is also allocated to handle decoding XDR data items that
cross page boundaries.

To demonstrate how it will be used, add the first call site for the
new svcxdr_init_decode() API.

As an additional part of the overall conversion, add symbolic
constants for successful and failed XDR operations. Returning "0" is
overloaded. Sometimes it means something failed, but sometimes it
means success. To make it more clear when XDR decoding functions
succeed or fail, introduce symbolic constants.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 27b1ad1361508b2813d9d521734f41b927f95968..74d5e58eadb05ec890a229f076f5958b214e33db 100644 (file)
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -1020,6 +1020,8 @@ int nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
         * (necessary in the NFSv4.0 compound case)
         */
        rqstp->rq_cachetype = proc->pc_cachetype;
+
+       svcxdr_init_decode(rqstp);
        if (!proc->pc_decode(rqstp, argv->iov_base))
                goto out_decode_err;
 

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index c220b734fa69e857151f5d0552a935d1660a16c5..34c2a69820e930d8b30693d1790ebbae1422b602 100644 (file)
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -247,6 +247,8 @@ struct svc_rqst {
 
        size_t                  rq_xprt_hlen;   /* xprt header len */
        struct xdr_buf          rq_arg;
+       struct xdr_stream       rq_arg_stream;
+       struct page             *rq_scratch_page;
        struct xdr_buf          rq_res;
        struct page             *rq_pages[RPCSVC_MAXPAGES + 1];
        struct page *           *rq_respages;   /* points into rq_pages */
@@ -557,4 +559,18 @@ static inline void svc_reserve_auth(struct svc_rqst *rqstp, int space)
        svc_reserve(rqstp, space + rqstp->rq_auth_slack);
 }
 
+/**
+ * svcxdr_init_decode - Prepare an xdr_stream for svc Call decoding
+ * @rqstp: controlling server RPC transaction context
+ *
+ */
+static inline void svcxdr_init_decode(struct svc_rqst *rqstp)
+{
+       struct xdr_stream *xdr = &rqstp->rq_arg_stream;
+       struct kvec *argv = rqstp->rq_arg.head;
+
+       xdr_init_decode(xdr, &rqstp->rq_arg, argv->iov_base, NULL);
+       xdr_set_scratch_page(xdr, rqstp->rq_scratch_page);
+}
+
 #endif /* SUNRPC_SVC_H */

diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index b41500645c3f05092fe307015e2ba526555ad678..4187745887f0f946017853924df0f6f2054f88ec 100644 (file)
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -614,6 +614,10 @@ svc_rqst_alloc(struct svc_serv *serv, struct svc_pool *pool, int node)
        rqstp->rq_server = serv;
        rqstp->rq_pool = pool;
 
+       rqstp->rq_scratch_page = alloc_pages_node(node, GFP_KERNEL, 0);
+       if (!rqstp->rq_scratch_page)
+               goto out_enomem;
+
        rqstp->rq_argp = kmalloc_node(serv->sv_xdrsize, GFP_KERNEL, node);
        if (!rqstp->rq_argp)
                goto out_enomem;
@@ -842,6 +846,7 @@ void
 svc_rqst_free(struct svc_rqst *rqstp)
 {
        svc_release_buffer(rqstp);
+       put_page(rqstp->rq_scratch_page);
        kfree(rqstp->rq_resp);
        kfree(rqstp->rq_argp);
        kfree(rqstp->rq_auth_data);