[SCSI] tcm_fc: Adding FC_FC4 provider (tcm_fc) for FCoE target (TCM - target core) support

This is a comprehensive patch for FC-FC4 provider. tcm_fc is a FC-FC4
provider which glues target core (TCM) with Fiber channel library
(libfc). tcm_fc uses existing FC4 provider hooks from Fiber channel
library. This Fiber channel library is used by FCoE (transport - FC
over Ethernet) protocol driver as well.

Combination of modules such as Fiber channel library, tcm_fc, TCM
target core, and FCoE protocol driver enables functional FCoE target.

This patch includes initial commit for tcm_fc plus additional
enhancement, bug fixes.

This tcm_fc module essentially contains 3 entry points such as "prli",
"prlo", "recv".  When process login request (ELS_PRLI) request is
received, Fiber channel library (libfc) module calls passive providers
(FC-FC4, tcm_fc) (if any registered) "prli" function. Likewise when
LOGO request is received, "prlo" function of passive provider is
invoked by libfc.  For all other request (e.g. any read/write, task
management, LUN inquiry commands), "recv" function of passiver
provider is invoked by libfc. Those passive providers "prli, prlo,
recv" functions interact with TCM target core for requested operation.

This module was primarily developed by "Joe Eykholt" and there were
significant contributions from the people listed under signed-off.

Signed-off-by: Joe Eykholt <jeykholt@cisco.com>
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: Kiran Patil <kiran.patil@intel.com>

Acked-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <jbottomley@parallels.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 541 insertions, 0 deletions

diff --git a/drivers/target/tcm_fc/tfc_sess.c b/drivers/target/tcm_fc/tfc_sess.c
new file mode 100644
index 0000000..a3bd57f
--- /dev/null
+++ b/drivers/target/tcm_fc/tfc_sess.c
@@ -0,0 +1,541 @@
+/*
+ * Copyright (c) 2010 Cisco Systems, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/* XXX TBD some includes may be extraneous */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/version.h>
+#include <generated/utsrelease.h>
+#include <linux/utsname.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/kthread.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/configfs.h>
+#include <linux/ctype.h>
+#include <linux/hash.h>
+#include <linux/rcupdate.h>
+#include <linux/rculist.h>
+#include <linux/kref.h>
+#include <asm/unaligned.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/libfc.h>
+
+#include <target/target_core_base.h>
+#include <target/target_core_transport.h>
+#include <target/target_core_fabric_ops.h>
+#include <target/target_core_device.h>
+#include <target/target_core_tpg.h>
+#include <target/target_core_configfs.h>
+#include <target/target_core_base.h>
+#include <target/configfs_macros.h>
+
+#include <scsi/libfc.h>
+#include "tcm_fc.h"
+
+static void ft_sess_delete_all(struct ft_tport *);
+
+/*
+ * Lookup or allocate target local port.
+ * Caller holds ft_lport_lock.
+ */
+static struct ft_tport *ft_tport_create(struct fc_lport *lport)
+{
+	struct ft_tpg *tpg;
+	struct ft_tport *tport;
+	int i;
+
+	tport = rcu_dereference(lport->prov[FC_TYPE_FCP]);
+	if (tport && tport->tpg)
+		return tport;
+
+	tpg = ft_lport_find_tpg(lport);
+	if (!tpg)
+		return NULL;
+
+	if (tport) {
+		tport->tpg = tpg;
+		return tport;
+	}
+
+	tport = kzalloc(sizeof(*tport), GFP_KERNEL);
+	if (!tport)
+		return NULL;
+
+	tport->lport = lport;
+	tport->tpg = tpg;
+	tpg->tport = tport;
+	for (i = 0; i < FT_SESS_HASH_SIZE; i++)
+		INIT_HLIST_HEAD(&tport->hash[i]);
+
+	rcu_assign_pointer(lport->prov[FC_TYPE_FCP], tport);
+	return tport;
+}
+
+/*
+ * Free tport via RCU.
+ */
+static void ft_tport_rcu_free(struct rcu_head *rcu)
+{
+	struct ft_tport *tport = container_of(rcu, struct ft_tport, rcu);
+
+	kfree(tport);
+}
+
+/*
+ * Delete a target local port.
+ * Caller holds ft_lport_lock.
+ */
+static void ft_tport_delete(struct ft_tport *tport)
+{
+	struct fc_lport *lport;
+	struct ft_tpg *tpg;
+
+	ft_sess_delete_all(tport);
+	lport = tport->lport;
+	BUG_ON(tport != lport->prov[FC_TYPE_FCP]);
+	rcu_assign_pointer(lport->prov[FC_TYPE_FCP], NULL);
+
+	tpg = tport->tpg;
+	if (tpg) {
+		tpg->tport = NULL;
+		tport->tpg = NULL;
+	}
+	call_rcu(&tport->rcu, ft_tport_rcu_free);
+}
+
+/*
+ * Add local port.
+ * Called thru fc_lport_iterate().
+ */
+void ft_lport_add(struct fc_lport *lport, void *arg)
+{
+	mutex_lock(&ft_lport_lock);
+	ft_tport_create(lport);
+	mutex_unlock(&ft_lport_lock);
+}
+
+/*
+ * Delete local port.
+ * Called thru fc_lport_iterate().
+ */
+void ft_lport_del(struct fc_lport *lport, void *arg)
+{
+	struct ft_tport *tport;
+
+	mutex_lock(&ft_lport_lock);
+	tport = lport->prov[FC_TYPE_FCP];
+	if (tport)
+		ft_tport_delete(tport);
+	mutex_unlock(&ft_lport_lock);
+}
+
+/*
+ * Notification of local port change from libfc.
+ * Create or delete local port and associated tport.
+ */
+int ft_lport_notify(struct notifier_block *nb, unsigned long event, void *arg)
+{
+	struct fc_lport *lport = arg;
+
+	switch (event) {
+	case FC_LPORT_EV_ADD:
+		ft_lport_add(lport, NULL);
+		break;
+	case FC_LPORT_EV_DEL:
+		ft_lport_del(lport, NULL);
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+/*
+ * Hash function for FC_IDs.
+ */
+static u32 ft_sess_hash(u32 port_id)
+{
+	return hash_32(port_id, FT_SESS_HASH_BITS);
+}
+
+/*
+ * Find session in local port.
+ * Sessions and hash lists are RCU-protected.
+ * A reference is taken which must be eventually freed.
+ */
+static struct ft_sess *ft_sess_get(struct fc_lport *lport, u32 port_id)
+{
+	struct ft_tport *tport;
+	struct hlist_head *head;
+	struct hlist_node *pos;
+	struct ft_sess *sess;
+
+	rcu_read_lock();
+	tport = rcu_dereference(lport->prov[FC_TYPE_FCP]);
+	if (!tport)
+		goto out;
+
+	head = &tport->hash[ft_sess_hash(port_id)];
+	hlist_for_each_entry_rcu(sess, pos, head, hash) {
+		if (sess->port_id == port_id) {
+			kref_get(&sess->kref);
+			rcu_read_unlock();
+			FT_SESS_DBG("port_id %x found %p\n", port_id, sess);
+			return sess;
+		}
+	}
+out:
+	rcu_read_unlock();
+	FT_SESS_DBG("port_id %x not found\n", port_id);
+	return NULL;
+}
+
+/*
+ * Allocate session and enter it in the hash for the local port.
+ * Caller holds ft_lport_lock.
+ */
+static struct ft_sess *ft_sess_create(struct ft_tport *tport, u32 port_id,
+				      struct ft_node_acl *acl)
+{
+	struct ft_sess *sess;
+	struct hlist_head *head;
+	struct hlist_node *pos;
+
+	head = &tport->hash[ft_sess_hash(port_id)];
+	hlist_for_each_entry_rcu(sess, pos, head, hash)
+		if (sess->port_id == port_id)
+			return sess;
+
+	sess = kzalloc(sizeof(*sess), GFP_KERNEL);
+	if (!sess)
+		return NULL;
+
+	sess->se_sess = transport_init_session();
+	if (!sess->se_sess) {
+		kfree(sess);
+		return NULL;
+	}
+	sess->se_sess->se_node_acl = &acl->se_node_acl;
+	sess->tport = tport;
+	sess->port_id = port_id;
+	kref_init(&sess->kref);	/* ref for table entry */
+	hlist_add_head_rcu(&sess->hash, head);
+	tport->sess_count++;
+
+	FT_SESS_DBG("port_id %x sess %p\n", port_id, sess);
+
+	transport_register_session(&tport->tpg->se_tpg, &acl->se_node_acl,
+				   sess->se_sess, sess);
+	return sess;
+}
+
+/*
+ * Unhash the session.
+ * Caller holds ft_lport_lock.
+ */
+static void ft_sess_unhash(struct ft_sess *sess)
+{
+	struct ft_tport *tport = sess->tport;
+
+	hlist_del_rcu(&sess->hash);
+	BUG_ON(!tport->sess_count);
+	tport->sess_count--;
+	sess->port_id = -1;
+	sess->params = 0;
+}
+
+/*
+ * Delete session from hash.
+ * Caller holds ft_lport_lock.
+ */
+static struct ft_sess *ft_sess_delete(struct ft_tport *tport, u32 port_id)
+{
+	struct hlist_head *head;
+	struct hlist_node *pos;
+	struct ft_sess *sess;
+
+	head = &tport->hash[ft_sess_hash(port_id)];
+	hlist_for_each_entry_rcu(sess, pos, head, hash) {
+		if (sess->port_id == port_id) {
+			ft_sess_unhash(sess);
+			return sess;
+		}
+	}
+	return NULL;
+}
+
+/*
+ * Delete all sessions from tport.
+ * Caller holds ft_lport_lock.
+ */
+static void ft_sess_delete_all(struct ft_tport *tport)
+{
+	struct hlist_head *head;
+	struct hlist_node *pos;
+	struct ft_sess *sess;
+
+	for (head = tport->hash;
+	     head < &tport->hash[FT_SESS_HASH_SIZE]; head++) {
+		hlist_for_each_entry_rcu(sess, pos, head, hash) {
+			ft_sess_unhash(sess);
+			transport_deregister_session_configfs(sess->se_sess);
+			ft_sess_put(sess);	/* release from table */
+		}
+	}
+}
+
+/*
+ * TCM ops for sessions.
+ */
+
+/*
+ * Determine whether session is allowed to be shutdown in the current context.
+ * Returns non-zero if the session should be shutdown.
+ */
+int ft_sess_shutdown(struct se_session *se_sess)
+{
+	struct ft_sess *sess = se_sess->fabric_sess_ptr;
+
+	FT_SESS_DBG("port_id %x\n", sess->port_id);
+	return 1;
+}
+
+/*
+ * Remove session and send PRLO.
+ * This is called when the ACL is being deleted or queue depth is changing.
+ */
+void ft_sess_close(struct se_session *se_sess)
+{
+	struct ft_sess *sess = se_sess->fabric_sess_ptr;
+	struct fc_lport *lport;
+	u32 port_id;
+
+	mutex_lock(&ft_lport_lock);
+	lport = sess->tport->lport;
+	port_id = sess->port_id;
+	if (port_id == -1) {
+		mutex_lock(&ft_lport_lock);
+		return;
+	}
+	FT_SESS_DBG("port_id %x\n", port_id);
+	ft_sess_unhash(sess);
+	mutex_unlock(&ft_lport_lock);
+	transport_deregister_session_configfs(se_sess);
+	ft_sess_put(sess);
+	/* XXX Send LOGO or PRLO */
+	synchronize_rcu();		/* let transport deregister happen */
+}
+
+void ft_sess_stop(struct se_session *se_sess, int sess_sleep, int conn_sleep)
+{
+	struct ft_sess *sess = se_sess->fabric_sess_ptr;
+
+	FT_SESS_DBG("port_id %x\n", sess->port_id);
+}
+
+int ft_sess_logged_in(struct se_session *se_sess)
+{
+	struct ft_sess *sess = se_sess->fabric_sess_ptr;
+
+	return sess->port_id != -1;
+}
+
+u32 ft_sess_get_index(struct se_session *se_sess)
+{
+	struct ft_sess *sess = se_sess->fabric_sess_ptr;
+
+	return sess->port_id;	/* XXX TBD probably not what is needed */
+}
+
+u32 ft_sess_get_port_name(struct se_session *se_sess,
+			  unsigned char *buf, u32 len)
+{
+	struct ft_sess *sess = se_sess->fabric_sess_ptr;
+
+	return ft_format_wwn(buf, len, sess->port_name);
+}
+
+void ft_sess_set_erl0(struct se_session *se_sess)
+{
+	/* XXX TBD called when out of memory */
+}
+
+/*
+ * libfc ops involving sessions.
+ */
+
+static int ft_prli_locked(struct fc_rport_priv *rdata, u32 spp_len,
+			  const struct fc_els_spp *rspp, struct fc_els_spp *spp)
+{
+	struct ft_tport *tport;
+	struct ft_sess *sess;
+	struct ft_node_acl *acl;
+	u32 fcp_parm;
+
+	tport = ft_tport_create(rdata->local_port);
+	if (!tport)
+		return 0;	/* not a target for this local port */
+
+	acl = ft_acl_get(tport->tpg, rdata);
+	if (!acl)
+		return 0;
+
+	if (!rspp)
+		goto fill;
+
+	if (rspp->spp_flags & (FC_SPP_OPA_VAL | FC_SPP_RPA_VAL))
+		return FC_SPP_RESP_NO_PA;
+
+	/*
+	 * If both target and initiator bits are off, the SPP is invalid.
+	 */
+	fcp_parm = ntohl(rspp->spp_params);
+	if (!(fcp_parm & (FCP_SPPF_INIT_FCN | FCP_SPPF_TARG_FCN)))
+		return FC_SPP_RESP_INVL;
+
+	/*
+	 * Create session (image pair) only if requested by
+	 * EST_IMG_PAIR flag and if the requestor is an initiator.
+	 */
+	if (rspp->spp_flags & FC_SPP_EST_IMG_PAIR) {
+		spp->spp_flags |= FC_SPP_EST_IMG_PAIR;
+		if (!(fcp_parm & FCP_SPPF_INIT_FCN))
+			return FC_SPP_RESP_CONF;
+		sess = ft_sess_create(tport, rdata->ids.port_id, acl);
+		if (!sess)
+			return FC_SPP_RESP_RES;
+		if (!sess->params)
+			rdata->prli_count++;
+		sess->params = fcp_parm;
+		sess->port_name = rdata->ids.port_name;
+		sess->max_frame = rdata->maxframe_size;
+
+		/* XXX TBD - clearing actions.  unit attn, see 4.10 */
+	}
+
+	/*
+	 * OR in our service parameters with other provider (initiator), if any.
+	 * TBD XXX - indicate RETRY capability?
+	 */
+fill:
+	fcp_parm = ntohl(spp->spp_params);
+	spp->spp_params = htonl(fcp_parm | FCP_SPPF_TARG_FCN);
+	return FC_SPP_RESP_ACK;
+}
+
+/**
+ * tcm_fcp_prli() - Handle incoming or outgoing PRLI for the FCP target
+ * @rdata: remote port private
+ * @spp_len: service parameter page length
+ * @rspp: received service parameter page (NULL for outgoing PRLI)
+ * @spp: response service parameter page
+ *
+ * Returns spp response code.
+ */
+static int ft_prli(struct fc_rport_priv *rdata, u32 spp_len,
+		   const struct fc_els_spp *rspp, struct fc_els_spp *spp)
+{
+	int ret;
+
+	mutex_lock(&ft_lport_lock);
+	ret = ft_prli_locked(rdata, spp_len, rspp, spp);
+	mutex_unlock(&ft_lport_lock);
+	FT_SESS_DBG("port_id %x flags %x ret %x\n",
+	       rdata->ids.port_id, rspp ? rspp->spp_flags : 0, ret);
+	return ret;
+}
+
+static void ft_sess_rcu_free(struct rcu_head *rcu)
+{
+	struct ft_sess *sess = container_of(rcu, struct ft_sess, rcu);
+
+	transport_deregister_session(sess->se_sess);
+	kfree(sess);
+}
+
+static void ft_sess_free(struct kref *kref)
+{
+	struct ft_sess *sess = container_of(kref, struct ft_sess, kref);
+
+	call_rcu(&sess->rcu, ft_sess_rcu_free);
+}
+
+void ft_sess_put(struct ft_sess *sess)
+{
+	int sess_held = atomic_read(&sess->kref.refcount);
+
+	BUG_ON(!sess_held);
+	kref_put(&sess->kref, ft_sess_free);
+}
+
+static void ft_prlo(struct fc_rport_priv *rdata)
+{
+	struct ft_sess *sess;
+	struct ft_tport *tport;
+
+	mutex_lock(&ft_lport_lock);
+	tport = rcu_dereference(rdata->local_port->prov[FC_TYPE_FCP]);
+	if (!tport) {
+		mutex_unlock(&ft_lport_lock);
+		return;
+	}
+	sess = ft_sess_delete(tport, rdata->ids.port_id);
+	if (!sess) {
+		mutex_unlock(&ft_lport_lock);
+		return;
+	}
+	mutex_unlock(&ft_lport_lock);
+	transport_deregister_session_configfs(sess->se_sess);
+	ft_sess_put(sess);		/* release from table */
+	rdata->prli_count--;
+	/* XXX TBD - clearing actions.  unit attn, see 4.10 */
+}
+
+/*
+ * Handle incoming FCP request.
+ * Caller has verified that the frame is type FCP.
+ */
+static void ft_recv(struct fc_lport *lport, struct fc_frame *fp)
+{
+	struct ft_sess *sess;
+	u32 sid = fc_frame_sid(fp);
+
+	FT_SESS_DBG("sid %x\n", sid);
+
+	sess = ft_sess_get(lport, sid);
+	if (!sess) {
+		FT_SESS_DBG("sid %x sess lookup failed\n", sid);
+		/* TBD XXX - if FCP_CMND, send PRLO */
+		fc_frame_free(fp);
+		return;
+	}
+	ft_recv_req(sess, fp);	/* must do ft_sess_put() */
+}
+
+/*
+ * Provider ops for libfc.
+ */
+struct fc4_prov ft_prov = {
+	.prli = ft_prli,
+	.prlo = ft_prlo,
+	.recv = ft_recv,
+	.module = THIS_MODULE,
+};