[PATCH v2 14/28] nfsd: add callback encoding and decoding linkages for CB_NOTIFY

Jeff Layton
2026-04-16T17:35:49Z

Add routines for encoding and decoding CB_NOTIFY messages. These call
into the code generated by xdrgen to do the actual encoding and
decoding.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
fs/nfsd/nfs4callback.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
fs/nfsd/state.h | 8 ++++++++
fs/nfsd/xdr4cb.h | 12 ++++++++++++
3 files changed, 66 insertions(+)

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 25bbf5b8814d..ea3e7deb06fa 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -865,6 +865,51 @@ static void encode_stateowner(struct xdr_stream *xdr, struct nfs4_stateowner *so
xdr_encode_opaque(p, so->so_owner.data, so->so_owner.len);
}

+static void nfs4_xdr_enc_cb_notify(struct rpc_rqst *req,
+ struct xdr_stream *xdr,
+ const void *data)
+{
+ const struct nfsd4_callback *cb = data;
+ struct nfs4_cb_compound_hdr hdr = {
+ .ident = 0,
+ .minorversion = cb->cb_clp->cl_minorversion,
+ };
+ struct CB_NOTIFY4args args = { };
+
+ WARN_ON_ONCE(hdr.minorversion == 0);
+
+ encode_cb_compound4args(xdr, &hdr);
+ encode_cb_sequence4args(xdr, cb, &hdr);
+
+ /*
+ * FIXME: get stateid and fh from delegation. Inline the cna_changes
+ * buffer, and zero it.
+ */
+ WARN_ON_ONCE(!xdrgen_encode_CB_NOTIFY4args(xdr, &args));
+
+ hdr.nops++;
+ encode_cb_nops(&hdr);
+}
+
+static int nfs4_xdr_dec_cb_notify(struct rpc_rqst *rqstp,
+ struct xdr_stream *xdr,
+ void *data)
+{
+ struct nfsd4_callback *cb = data;
+ struct nfs4_cb_compound_hdr hdr;
+ int status;
+
+ status = decode_cb_compound4res(xdr, &hdr);
+ if (unlikely(status))
+ return status;
+
+ status = decode_cb_sequence4res(xdr, cb);
+ if (unlikely(status || cb->cb_seq_status))
+ return status;
+
+ return decode_cb_op_status(xdr, OP_CB_NOTIFY, &cb->cb_status);
+}
+
static void nfs4_xdr_enc_cb_notify_lock(struct rpc_rqst *req,
struct xdr_stream *xdr,
const void *data)
@@ -1026,6 +1071,7 @@ static const struct rpc_procinfo nfs4_cb_procedures[] = {
#ifdef CONFIG_NFSD_PNFS
PROC(CB_LAYOUT, COMPOUND, cb_layout, cb_layout),
#endif
+ PROC(CB_NOTIFY, COMPOUND, cb_notify, cb_notify),
PROC(CB_NOTIFY_LOCK, COMPOUND, cb_notify_lock, cb_notify_lock),
PROC(CB_OFFLOAD, COMPOUND, cb_offload, cb_offload),
PROC(CB_RECALL_ANY, COMPOUND, cb_recall_any, cb_recall_any),
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index 7d2afe7dcc3e..22c9a1e7d8fd 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -190,6 +190,13 @@ struct nfs4_cb_fattr {
u64 ncf_cur_fsize;
};

+/*
+ * FIXME: the current backchannel encoder can't handle a send buffer longer
+ * than a single page (see bc_alloc/bc_free).
+ */
+#define NOTIFY4_EVENT_QUEUE_SIZE 3
+#define NOTIFY4_PAGE_ARRAY_SIZE 1
+
/*
* Represents a delegation stateid. The nfs4_client holds references to these
* and they are put when it is being destroyed or when the delegation is
@@ -774,6 +781,7 @@ enum nfsd4_cb_op {
NFSPROC4_CLNT_CB_NOTIFY_LOCK,
NFSPROC4_CLNT_CB_RECALL_ANY,
NFSPROC4_CLNT_CB_GETATTR,
+ NFSPROC4_CLNT_CB_NOTIFY,
};

/* Returns true iff a is later than b: */
diff --git a/fs/nfsd/xdr4cb.h b/fs/nfsd/xdr4cb.h
index f4e29c0c701c..b06d0170d7c4 100644
--- a/fs/nfsd/xdr4cb.h
+++ b/fs/nfsd/xdr4cb.h
@@ -33,6 +33,18 @@
cb_sequence_dec_sz + \
op_dec_sz)

+#define NFS4_enc_cb_notify_sz (cb_compound_enc_hdr_sz + \
+ cb_sequence_enc_sz + \
+ 1 + enc_stateid_sz + \
+ enc_nfs4_fh_sz + \
+ 1 + \
+ NOTIFY4_EVENT_QUEUE_SIZE * \
+ (2 + (NFS4_OPAQUE_LIMIT >> 2)))
+
+#define NFS4_dec_cb_notify_sz (cb_compound_dec_hdr_sz + \
+ cb_sequence_dec_sz + \
+ op_dec_sz)
+
#define NFS4_enc_cb_notify_lock_sz (cb_compound_enc_hdr_sz + \
cb_sequence_enc_sz + \
2 + 1 + \

--
2.53.0