+static void
+gen_sessionid(struct nfsd4_session *ses)
+{
+ struct nfs4_client *clp = ses->se_client;
+ struct nfsd4_sessionid *sid;
+
+ sid = (struct nfsd4_sessionid *)ses->se_sessionid.data;
+ sid->clientid = clp->cl_clientid;
+ sid->sequence = current_sessionid++;
+ sid->reserved = 0;
+}
+
+/*
+ * The protocol defines ca_maxresponssize_cached to include the size of
+ * the rpc header, but all we need to cache is the data starting after
+ * the end of the initial SEQUENCE operation--the rest we regenerate
+ * each time. Therefore we can advertise a ca_maxresponssize_cached
+ * value that is the number of bytes in our cache plus a few additional
+ * bytes. In order to stay on the safe side, and not promise more than
+ * we can cache, those additional bytes must be the minimum possible: 24
+ * bytes of rpc header (xid through accept state, with AUTH_NULL
+ * verifier), 12 for the compound header (with zero-length tag), and 44
+ * for the SEQUENCE op response:
+ */
+#define NFSD_MIN_HDR_SEQ_SZ (24 + 12 + 44)
+
+/*
+ * Give the client the number of ca_maxresponsesize_cached slots it
+ * requests, of size bounded by NFSD_SLOT_CACHE_SIZE,
+ * NFSD_MAX_MEM_PER_SESSION, and nfsd_drc_max_mem. Do not allow more
+ * than NFSD_MAX_SLOTS_PER_SESSION.
+ *
+ * If we run out of reserved DRC memory we should (up to a point)
+ * re-negotiate active sessions and reduce their slot usage to make
+ * rooom for new connections. For now we just fail the create session.
+ */
+static int set_forechannel_drc_size(struct nfsd4_channel_attrs *fchan)
+{
+ int mem, size = fchan->maxresp_cached;
+
+ if (fchan->maxreqs < 1)
+ return nfserr_inval;
+
+ if (size < NFSD_MIN_HDR_SEQ_SZ)
+ size = NFSD_MIN_HDR_SEQ_SZ;
+ size -= NFSD_MIN_HDR_SEQ_SZ;
+ if (size > NFSD_SLOT_CACHE_SIZE)
+ size = NFSD_SLOT_CACHE_SIZE;
+
+ /* bound the maxreqs by NFSD_MAX_MEM_PER_SESSION */
+ mem = fchan->maxreqs * size;
+ if (mem > NFSD_MAX_MEM_PER_SESSION) {
+ fchan->maxreqs = NFSD_MAX_MEM_PER_SESSION / size;
+ if (fchan->maxreqs > NFSD_MAX_SLOTS_PER_SESSION)
+ fchan->maxreqs = NFSD_MAX_SLOTS_PER_SESSION;
+ mem = fchan->maxreqs * size;
+ }
+
+ spin_lock(&nfsd_drc_lock);
+ /* bound the total session drc memory ussage */
+ if (mem + nfsd_drc_mem_used > nfsd_drc_max_mem) {
+ fchan->maxreqs = (nfsd_drc_max_mem - nfsd_drc_mem_used) / size;
+ mem = fchan->maxreqs * size;
+ }
+ nfsd_drc_mem_used += mem;
+ spin_unlock(&nfsd_drc_lock);
+
+ if (fchan->maxreqs == 0)
+ return nfserr_serverfault;
+
+ fchan->maxresp_cached = size + NFSD_MIN_HDR_SEQ_SZ;
+ return 0;
+}
+
+/*
+ * fchan holds the client values on input, and the server values on output
+ * sv_max_mesg is the maximum payload plus one page for overhead.
+ */
+static int init_forechannel_attrs(struct svc_rqst *rqstp,
+ struct nfsd4_channel_attrs *session_fchan,
+ struct nfsd4_channel_attrs *fchan)
+{
+ int status = 0;
+ __u32 maxcount = nfsd_serv->sv_max_mesg;
+
+ /* headerpadsz set to zero in encode routine */
+
+ /* Use the client's max request and max response size if possible */
+ if (fchan->maxreq_sz > maxcount)
+ fchan->maxreq_sz = maxcount;
+ session_fchan->maxreq_sz = fchan->maxreq_sz;
+
+ if (fchan->maxresp_sz > maxcount)
+ fchan->maxresp_sz = maxcount;
+ session_fchan->maxresp_sz = fchan->maxresp_sz;
+
+ /* Use the client's maxops if possible */
+ if (fchan->maxops > NFSD_MAX_OPS_PER_COMPOUND)
+ fchan->maxops = NFSD_MAX_OPS_PER_COMPOUND;
+ session_fchan->maxops = fchan->maxops;
+
+ /* FIXME: Error means no more DRC pages so the server should
+ * recover pages from existing sessions. For now fail session
+ * creation.
+ */
+ status = set_forechannel_drc_size(fchan);
+
+ session_fchan->maxresp_cached = fchan->maxresp_cached;
+ session_fchan->maxreqs = fchan->maxreqs;
+
+ dprintk("%s status %d\n", __func__, status);
+ return status;
+}
+
+static void
+free_session_slots(struct nfsd4_session *ses)
+{
+ int i;
+
+ for (i = 0; i < ses->se_fchannel.maxreqs; i++)
+ kfree(ses->se_slots[i]);
+}
+
+/*
+ * We don't actually need to cache the rpc and session headers, so we
+ * can allocate a little less for each slot:
+ */
+static inline int slot_bytes(struct nfsd4_channel_attrs *ca)
+{
+ return ca->maxresp_cached - NFSD_MIN_HDR_SEQ_SZ;
+}
+
+static int
+alloc_init_session(struct svc_rqst *rqstp, struct nfs4_client *clp,
+ struct nfsd4_create_session *cses)
+{
+ struct nfsd4_session *new, tmp;
+ struct nfsd4_slot *sp;
+ int idx, slotsize, cachesize, i;
+ int status;
+
+ memset(&tmp, 0, sizeof(tmp));
+
+ /* FIXME: For now, we just accept the client back channel attributes. */
+ tmp.se_bchannel = cses->back_channel;
+ status = init_forechannel_attrs(rqstp, &tmp.se_fchannel,
+ &cses->fore_channel);
+ if (status)
+ goto out;
+
+ BUILD_BUG_ON(NFSD_MAX_SLOTS_PER_SESSION * sizeof(struct nfsd4_slot)
+ + sizeof(struct nfsd4_session) > PAGE_SIZE);
+
+ status = nfserr_serverfault;
+ /* allocate struct nfsd4_session and slot table pointers in one piece */
+ slotsize = tmp.se_fchannel.maxreqs * sizeof(struct nfsd4_slot *);
+ new = kzalloc(sizeof(*new) + slotsize, GFP_KERNEL);
+ if (!new)
+ goto out;
+
+ memcpy(new, &tmp, sizeof(*new));
+
+ /* allocate each struct nfsd4_slot and data cache in one piece */
+ cachesize = slot_bytes(&new->se_fchannel);
+ for (i = 0; i < new->se_fchannel.maxreqs; i++) {
+ sp = kzalloc(sizeof(*sp) + cachesize, GFP_KERNEL);
+ if (!sp)
+ goto out_free;
+ new->se_slots[i] = sp;
+ }
+
+ new->se_client = clp;
+ gen_sessionid(new);
+ idx = hash_sessionid(&new->se_sessionid);
+ memcpy(clp->cl_sessionid.data, new->se_sessionid.data,
+ NFS4_MAX_SESSIONID_LEN);
+
+ new->se_flags = cses->flags;
+ kref_init(&new->se_ref);
+ spin_lock(&client_lock);
+ list_add(&new->se_hash, &sessionid_hashtbl[idx]);
+ list_add(&new->se_perclnt, &clp->cl_sessions);
+ spin_unlock(&client_lock);
+
+ status = nfs_ok;
+out:
+ return status;
+out_free:
+ free_session_slots(new);
+ kfree(new);
+ goto out;
+}
+
+/* caller must hold client_lock */