nfsd41: create_session operation

Implement the create_session operation confoming to
http://tools.ietf.org/html/draft-ietf-nfsv4-minorversion1-26

Look up the client id (generated by the server on exchange_id,
given by the client on create_session).
If neither a confirmed or unconfirmed client is found
then the client id is stale
If a confirmed cilent is found (i.e. we already received
create_session for it) then compare the sequence id
to determine if it's a replay or possibly a mis-ordered rpc.
If the seqid is in order, update the confirmed client seqid
and procedd with updating the session parameters.

If an unconfirmed client_id is found then verify the creds
and seqid.  If both match move the client id to confirmed state
and proceed with processing the create_session.

Currently, we do not support persistent sessions, and RDMA.

alloc_init_session generates a new sessionid and creates
a session structure.

NFSD_PAGES_PER_SLOT is used for the max response cached calculation, and for
the counting of DRC pages using the hard limits set in struct srv_serv.

A note on NFSD_PAGES_PER_SLOT:

Other patches in this series allow for NFSD_PAGES_PER_SLOT + 1 pages to be
cached in a DRC slot when the response size is less than NFSD_PAGES_PER_SLOT *
PAGE_SIZE but xdr_buf pages are used. e.g. a READDIR operation will encode a
small amount of data in the xdr_buf head, and then the READDIR in the xdr_buf
pages.  So, the hard limit calculation use of pages by a session is
underestimated by the number of cached operations using the xdr_buf pages.

Yet another patch caches no pages for the solo sequence operation, or any
compound where cache_this is False.  So the hard limit calculation use of
pages by a session is overestimated by the number of these operations in the
cache.

TODO: improve resource pre-allocation and negotiate session
parameters accordingly.  Respect and possibly adjust
backchannel attributes.

Signed-off-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: Dean Hildebrand <dhildeb@us.ibm.com>
[nfsd41: remove headerpadsz from channel attributes]
Our client and server only support a headerpadsz of 0.
[nfsd41: use DRC limits in fore channel init]
[nfsd41: do not change CREATE_SESSION back channel attrs]
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[use sessionid_lock spin lock]
[nfsd41: use bool inuse for slot state]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[nfsd41 remove sl_session from alloc_init_session]
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[simplify nfsd4_encode_create_session error handling]
[nfsd41: fix comment style in init_forechannel_attrs]
[nfsd41: allocate struct nfsd4_session and slot table in one piece]
[nfsd41: no need to INIT_LIST_HEAD in alloc_init_session just prior to list_add]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 187 insertions, 1 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index f25a7d2a9fa..463ae39df14 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -68,6 +68,7 @@ static u32 current_delegid = 1;
 static u32 nfs4_init;
 static stateid_t zerostateid;             /* bits all 0 */
 static stateid_t onestateid;              /* bits all 1 */
+static u64 current_sessionid = 1;
 
 #define ZERO_STATEID(stateid) (!memcmp((stateid), &zerostateid, sizeof(stateid_t)))
 #define ONE_STATEID(stateid)  (!memcmp((stateid), &onestateid, sizeof(stateid_t)))
@@ -401,6 +402,131 @@ dump_sessionid(const char *fn, struct nfs4_sessionid *sessionid)
 	dprintk("%s: %u:%u:%u:%u\n", fn, ptr[0], ptr[1], ptr[2], ptr[3]);
 }
 
+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;
+}
+
+/*
+ * Give the client the number of slots it requests bound by
+ * NFSD_MAX_SLOTS_PER_SESSION and by sv_drc_max_pages.
+ *
+ * If we run out of pages (sv_drc_pages_used == sv_drc_max_pages) 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_maxreqs(struct nfsd4_channel_attrs *fchan)
+{
+	int status = 0, np = fchan->maxreqs * NFSD_PAGES_PER_SLOT;
+
+	spin_lock(&nfsd_serv->sv_lock);
+	if (np + nfsd_serv->sv_drc_pages_used > nfsd_serv->sv_drc_max_pages)
+		np = nfsd_serv->sv_drc_max_pages - nfsd_serv->sv_drc_pages_used;
+	nfsd_serv->sv_drc_pages_used += np;
+	spin_unlock(&nfsd_serv->sv_lock);
+
+	if (np <= 0) {
+		status = nfserr_resource;
+		fchan->maxreqs = 0;
+	} else
+		fchan->maxreqs = np / NFSD_PAGES_PER_SLOT;
+
+	return status;
+}
+
+/*
+ * fchan holds the client values on input, and the server values on output
+ */
+static int init_forechannel_attrs(struct svc_rqst *rqstp,
+				    struct nfsd4_session *session,
+				    struct nfsd4_channel_attrs *fchan)
+{
+	int status = 0;
+	__u32   maxcount = svc_max_payload(rqstp);
+
+	/* 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->se_fmaxreq_sz = fchan->maxreq_sz;
+
+	if (fchan->maxresp_sz > maxcount)
+		fchan->maxresp_sz = maxcount;
+	session->se_fmaxresp_sz = fchan->maxresp_sz;
+
+	/* Set the max response cached size our default which is
+	 * a multiple of PAGE_SIZE and small */
+	session->se_fmaxresp_cached = NFSD_PAGES_PER_SLOT * PAGE_SIZE;
+	fchan->maxresp_cached = session->se_fmaxresp_cached;
+
+	/* Use the client's maxops if possible */
+	if (fchan->maxops > NFSD_MAX_OPS_PER_COMPOUND)
+		fchan->maxops = NFSD_MAX_OPS_PER_COMPOUND;
+	session->se_fmaxops = fchan->maxops;
+
+	/* try to use the client requested number of slots */
+	if (fchan->maxreqs > NFSD_MAX_SLOTS_PER_SESSION)
+		fchan->maxreqs = NFSD_MAX_SLOTS_PER_SESSION;
+
+	/* FIXME: Error means no more DRC pages so the server should
+	 * recover pages from existing sessions. For now fail session
+	 * creation.
+	 */
+	status = set_forechannel_maxreqs(fchan);
+
+	session->se_fnumslots = fchan->maxreqs;
+	return status;
+}
+
+static int
+alloc_init_session(struct svc_rqst *rqstp, struct nfs4_client *clp,
+		   struct nfsd4_create_session *cses)
+{
+	struct nfsd4_session *new, tmp;
+	int idx, status = nfserr_resource, slotsize;
+
+	memset(&tmp, 0, sizeof(tmp));
+
+	/* FIXME: For now, we just accept the client back channel attributes. */
+	status = init_forechannel_attrs(rqstp, &tmp, &cses->fore_channel);
+	if (status)
+		goto out;
+
+	/* allocate struct nfsd4_session and slot table in one piece */
+	slotsize = tmp.se_fnumslots * sizeof(struct nfsd4_slot);
+	new = kzalloc(sizeof(*new) + slotsize, GFP_KERNEL);
+	if (!new)
+		goto out;
+
+	memcpy(new, &tmp, sizeof(*new));
+
+	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(&sessionid_lock);
+	list_add(&new->se_hash, &sessionid_hashtbl[idx]);
+	list_add(&new->se_perclnt, &clp->cl_sessions);
+	spin_unlock(&sessionid_lock);
+
+	status = nfs_ok;
+out:
+	return status;
+}
+
 /* caller must hold sessionid_lock */
 static struct nfsd4_session *
 find_in_sessionid_hashtbl(struct nfs4_sessionid *sessionid)
@@ -1182,7 +1308,67 @@ nfsd4_create_session(struct svc_rqst *rqstp,
 		     struct nfsd4_compound_state *cstate,
 		     struct nfsd4_create_session *cr_ses)
 {
-	return -1;	/* stub */
+	u32 ip_addr = svc_addr_in(rqstp)->sin_addr.s_addr;
+	struct nfs4_client *conf, *unconf;
+	int status = 0;
+
+	nfs4_lock_state();
+	unconf = find_unconfirmed_client(&cr_ses->clientid);
+	conf = find_confirmed_client(&cr_ses->clientid);
+
+	if (conf) {
+		status = nfs_ok;
+		if (conf->cl_seqid == cr_ses->seqid) {
+			dprintk("Got a create_session replay! seqid= %d\n",
+				conf->cl_seqid);
+			goto out_replay;
+		} else if (cr_ses->seqid != conf->cl_seqid + 1) {
+			status = nfserr_seq_misordered;
+			dprintk("Sequence misordered!\n");
+			dprintk("Expected seqid= %d but got seqid= %d\n",
+				conf->cl_seqid, cr_ses->seqid);
+			goto out;
+		}
+		conf->cl_seqid++;
+	} else if (unconf) {
+		if (!same_creds(&unconf->cl_cred, &rqstp->rq_cred) ||
+		    (ip_addr != unconf->cl_addr)) {
+			status = nfserr_clid_inuse;
+			goto out;
+		}
+
+		if (unconf->cl_seqid != cr_ses->seqid) {
+			status = nfserr_seq_misordered;
+			goto out;
+		}
+
+		move_to_confirmed(unconf);
+
+		/*
+		 * We do not support RDMA or persistent sessions
+		 */
+		cr_ses->flags &= ~SESSION4_PERSIST;
+		cr_ses->flags &= ~SESSION4_RDMA;
+
+		conf = unconf;
+	} else {
+		status = nfserr_stale_clientid;
+		goto out;
+	}
+
+	status = alloc_init_session(rqstp, conf, cr_ses);
+	if (status)
+		goto out;
+
+out_replay:
+	memcpy(cr_ses->sessionid.data, conf->cl_sessionid.data,
+	       NFS4_MAX_SESSIONID_LEN);
+	cr_ses->seqid = conf->cl_seqid;
+
+out:
+	nfs4_unlock_state();
+	dprintk("%s returns %d\n", __func__, ntohl(status));
+	return status;
 }
 
 __be32