Message-Id: <1238904094.4250.742.camel@haakon2.linux-iscsi.org>
Date:	Sat, 04 Apr 2009 21:01:34 -0700
From:	"Nicholas A. Bellinger" <nab@...ux-iscsi.org>
To:	LKML <linux-kernel@...r.kernel.org>,
	linux-scsi <linux-scsi@...r.kernel.org>
Cc:	James Bottomley <James.Bottomley@...senPartnership.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hannes Reinecke <hare@...e.de>,
	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
	Mike Christie <michaelc@...wisc.edu>,
	Joel Becker <joel.becker@...cle.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	Ming Zhang <blackmagic02881@...il.com>,
	Philipp Reisner <philipp.reisner@...bit.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [RFC PATCH 1/19] Target_Core_Mod Asymmetric Logical Unit
	Assignment (ALUA) support

This patch adds implict ALUA using Optimized and Non Optimized Access states
Logical Unit and Target Port Groups.

Signed-off-by: Nicholas A. Bellinger <nab@...ux-iscsi.org>

diff --git a/drivers/target/target_core_alua.c b/drivers/target/target_core_alua.c
new file mode 100644
index 0000000..1c8f35b
--- /dev/null
+++ b/drivers/target/target_core_alua.c
@@ -0,0 +1,718 @@
+/*******************************************************************************
+ * Filename:  target_core_alua.c
+ *
+ * This file contains SPC-3 compliant asymmetric logical unit assigntment (ALUA)
+ *
+ * Copyright (c) 2009 Rising Tide, Inc.
+ * Copyright (c) 2009 Linux-iSCSI.org
+ *
+ * Nicholas A. Bellinger <nab@...nel.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ ******************************************************************************/
+
+#define TARGET_CORE_ALUA_C
+
+#include <linux/version.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+
+#include <target/target_core_base.h>
+#include <target/target_core_device.h>
+#include <target/target_core_hba.h>
+#include <target/target_core_transport.h>
+#include <target/target_core_alua.h>
+#include <target/target_core_transport_plugin.h>
+#include <target/target_core_fabric_ops.h>
+#include <target/target_core_configfs.h>
+
+#undef TARGET_CORE_ALUA_C
+
+/*
+ * REPORT_TARGET_PORT_GROUPS
+ *
+ * See spc4r17 6.2.7
+ */
+int core_scsi3_emulate_report_target_port_groups(se_cmd_t *cmd)
+{
+	se_port_t *port;
+	t10_alua_tg_pt_gp_t *tg_pt_gp;
+	t10_alua_tg_pt_gp_member_t *tg_pt_gp_mem;
+	unsigned char *buf = (unsigned char *)T_TASK(cmd)->t_task_buf;
+	u32 rd_len = 0, off = 4;
+
+	spin_lock(&se_global->tg_pt_gps_lock);
+	list_for_each_entry(tg_pt_gp, &se_global->g_tg_pt_gps_list,
+			tg_pt_gp_list) {
+		/*
+		 * PREF: Preferred target port bit
+		 */
+/*		buf[off] = 0x80; */
+		/*
+		 * Set the ASYMMETRIC ACCESS State
+		 */
+		buf[off++] |= (tg_pt_gp->tg_pt_gp_alua_access_state & 0xff);
+		/*
+		 * Set supported ASYMMETRIC ACCESS State bits
+		 */
+/*		buf[off] = 0x80; // T_SUP */
+/*		buf[off] |= 0x40; // O_SUP */
+/*		buf[off] |= 0x8; // U_SUP */
+/*		buf[off] |= 0x4; // S_SUP */
+		buf[off] |= 0x2; /* AN_SUP */
+		buf[off++] |= 0x1; /* AO_SUP */
+		/*
+		 * TARGET PORT GROUP
+		 */
+		buf[off++] = ((tg_pt_gp->tg_pt_gp_id >> 8) & 0xff);
+		buf[off++] = (tg_pt_gp->tg_pt_gp_id & 0xff);
+
+		off++; /* Skip over Reserved */
+		/*
+		 * STATUS CODE
+		 */
+		buf[off++] = ALUA_STATUS_ALTERED_BY_IMPLICT_ALUA;
+		/*
+		 * Vendor Specific field
+		 */
+		buf[off++] = 0x00;
+		/*
+		 * TARGET PORT COUNT
+		 */
+		buf[off++] = (tg_pt_gp->tg_pt_gp_members & 0xff);
+		rd_len += 8;
+
+		spin_lock(&tg_pt_gp->tg_pt_gp_lock);
+		list_for_each_entry(tg_pt_gp_mem, &tg_pt_gp->tg_pt_gp_mem_list,
+				tg_pt_gp_mem_list) {
+			port = tg_pt_gp_mem->tg_pt;
+			/*
+			 * Start Target Port descriptor format
+			 *
+			 * See spc4r17 section 6.2.7 Table 247
+			 */
+			off += 2; /* Skip over Obsolete */
+			/*
+			 * Set RELATIVE TARGET PORT IDENTIFIER
+			 */
+			buf[off++] = ((port->sep_rtpi >> 8) & 0xff);
+			buf[off++] = (port->sep_rtpi & 0xff);
+			rd_len += 4;
+		}
+		spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
+	}
+	spin_unlock(&se_global->tg_pt_gps_lock);
+	/*
+	 * Set the RETURN DATA LENGTH set in the header of the DataIN Payload
+	 */
+	buf[0] = ((rd_len >> 24) & 0xff);
+	buf[1] = ((rd_len >> 16) & 0xff);
+	buf[2] = ((rd_len >> 8) & 0xff);
+	buf[3] = (rd_len & 0xff);
+
+	return 0;
+}
+
+t10_alua_lu_gp_t *core_alua_allocate_lu_gp(const char *name)
+{
+	t10_alua_lu_gp_t *lu_gp, *lu_gp_tmp;
+
+	lu_gp = kmem_cache_zalloc(t10_alua_lu_gp_cache, GFP_KERNEL);
+	if (!(lu_gp)) {
+		printk(KERN_ERR "Unable to allocate t10_alua_lu_gp_t\n");
+		return NULL;
+	}
+	INIT_LIST_HEAD(&lu_gp->lu_gp_list);
+	INIT_LIST_HEAD(&lu_gp->lu_gp_mem_list);
+	spin_lock_init(&lu_gp->lu_gp_lock);
+	atomic_set(&lu_gp->lu_gp_ref_cnt, 0);
+	lu_gp->lu_gp_alua_access_state = ALUA_ACCESS_STATE_ACTIVE_OPTMIZED;
+
+	spin_lock(&se_global->lu_gps_lock);
+	if (se_global->alua_lu_gps_count == 0x0000ffff) {
+		spin_unlock(&se_global->lu_gps_lock);
+		kmem_cache_free(t10_alua_lu_gp_cache, lu_gp);
+		return NULL;
+	}
+again:
+	lu_gp->lu_gp_id = se_global->alua_lu_gps_counter++;
+
+	list_for_each_entry(lu_gp_tmp, &se_global->g_lu_gps_list, lu_gp_list) {
+		if (lu_gp_tmp->lu_gp_id == lu_gp->lu_gp_id)
+			goto again;
+	}
+
+	list_add_tail(&lu_gp->lu_gp_list, &se_global->g_lu_gps_list);
+	se_global->alua_lu_gps_count++;
+	spin_unlock(&se_global->lu_gps_lock);
+
+	return lu_gp;
+}
+
+t10_alua_lu_gp_member_t *core_alua_allocate_lu_gp_mem(
+	se_device_t *dev)
+{
+	t10_alua_lu_gp_member_t *lu_gp_mem;
+
+	lu_gp_mem = kmem_cache_zalloc(t10_alua_lu_gp_mem_cache, GFP_KERNEL);
+	if (!(lu_gp_mem)) {
+		printk(KERN_ERR "Unable to allocate t10_alua_lu_gp_member_t\n");
+		return ERR_PTR(-ENOMEM);
+	}
+	INIT_LIST_HEAD(&lu_gp_mem->lu_gp_mem_list);
+	spin_lock_init(&lu_gp_mem->lu_gp_mem_lock);
+
+	lu_gp_mem->lu_gp_mem_dev = dev;
+	dev->dev_alua_lu_gp_mem = lu_gp_mem;
+
+	return lu_gp_mem;
+}
+
+void core_alua_free_lu_gp(t10_alua_lu_gp_t *lu_gp)
+{
+	t10_alua_lu_gp_member_t *lu_gp_mem, *lu_gp_mem_tmp;
+	/*
+	 * Once we have reached this point, config_item_put() has
+	 * already been called from target_core_alua_drop_lu_gp().
+	 *
+	 * Here, we remove the *lu_gp from the global list so that
+	 * no associations can be made while we are releasing
+	 * t10_alua_lu_gp_t.
+	 */
+	spin_lock(&se_global->lu_gps_lock);
+	atomic_set(&lu_gp->lu_gp_shutdown, 1);
+	list_del(&lu_gp->lu_gp_list);
+	se_global->alua_lu_gps_count--;
+	spin_unlock(&se_global->lu_gps_lock);
+	/*
+	 * Allow t10_alua_lu_gp_t * referenced by core_alua_get_lu_gp_by_name()
+	 * in target_core_configfs.c:target_core_store_alua_lu_gp() to be
+	 * released with core_alua_put_lu_gp_from_name()
+	 */
+	while (atomic_read(&lu_gp->lu_gp_ref_cnt))
+		msleep(10);
+	/*
+	 * Release reference to t10_alua_lu_gp_t * from all associated
+	 * se_device_t.
+	 */
+	spin_lock(&lu_gp->lu_gp_lock);
+	list_for_each_entry_safe(lu_gp_mem, lu_gp_mem_tmp,
+				&lu_gp->lu_gp_mem_list, lu_gp_mem_list) {
+		if (lu_gp_mem->lu_gp_assoc) {
+			list_del(&lu_gp_mem->lu_gp_mem_list);
+			lu_gp->lu_gp_members--;
+			lu_gp_mem->lu_gp_assoc = 0;
+		}
+		spin_unlock(&lu_gp->lu_gp_lock);
+		/*
+		 *
+		 * lu_gp_mem is assoicated with a single
+		 * se_device_t->dev_alua_lu_gp_mem, and is released when
+		 * se_device_t is released via core_alua_free_lu_gp_mem().
+		 *
+		 * If the passed lu_gp does NOT match the default_lu_gp, assume
+		 * we want to re-assocate a given lu_gp_mem with default_lu_gp.
+		 */
+		spin_lock(&lu_gp_mem->lu_gp_mem_lock);
+		if (lu_gp != se_global->default_lu_gp)
+			__core_alua_attach_lu_gp_mem(lu_gp_mem,
+					se_global->default_lu_gp);
+		else
+			lu_gp_mem->lu_gp = NULL;
+		spin_unlock(&lu_gp_mem->lu_gp_mem_lock);
+
+		spin_lock(&lu_gp->lu_gp_lock);
+	}
+	spin_unlock(&lu_gp->lu_gp_lock);
+
+	kmem_cache_free(t10_alua_lu_gp_cache, lu_gp);
+}
+
+void core_alua_free_lu_gp_mem(se_device_t *dev)
+{
+	se_subsystem_dev_t *su_dev = dev->se_sub_dev;
+	t10_alua_t *alua = T10_ALUA(su_dev);
+	t10_alua_lu_gp_t *lu_gp;
+	t10_alua_lu_gp_member_t *lu_gp_mem;
+
+	if (alua->alua_type != SPC3_ALUA_EMULATED)
+		return;
+
+	lu_gp_mem = dev->dev_alua_lu_gp_mem;
+	if (!(lu_gp_mem))
+		return;
+
+	spin_lock(&lu_gp_mem->lu_gp_mem_lock);
+	lu_gp = lu_gp_mem->lu_gp;
+	if ((lu_gp)) {
+		spin_lock(&lu_gp->lu_gp_lock);
+		if (lu_gp_mem->lu_gp_assoc) {
+			list_del(&lu_gp_mem->lu_gp_mem_list);
+			lu_gp->lu_gp_members--;
+			lu_gp_mem->lu_gp_assoc = 0;
+		}
+		spin_unlock(&lu_gp->lu_gp_lock);
+		lu_gp_mem->lu_gp = NULL;
+	}
+	spin_unlock(&lu_gp_mem->lu_gp_mem_lock);
+
+	kmem_cache_free(t10_alua_lu_gp_mem_cache, lu_gp_mem);
+}
+
+t10_alua_lu_gp_t *core_alua_get_lu_gp_by_name(const char *name)
+{
+	t10_alua_lu_gp_t *lu_gp;
+	struct config_item *ci;
+
+	spin_lock(&se_global->lu_gps_lock);
+	list_for_each_entry(lu_gp, &se_global->g_lu_gps_list, lu_gp_list) {
+		ci = &lu_gp->lu_gp_group.cg_item;
+		if (!(strcmp(config_item_name(ci), name))) {
+			atomic_inc(&lu_gp->lu_gp_ref_cnt);
+			spin_unlock(&se_global->lu_gps_lock);
+			return lu_gp;
+		}
+	}
+	spin_unlock(&se_global->lu_gps_lock);
+
+	return NULL;
+}
+
+void core_alua_put_lu_gp_from_name(t10_alua_lu_gp_t *lu_gp)
+{
+	spin_lock(&se_global->lu_gps_lock);
+	atomic_dec(&lu_gp->lu_gp_ref_cnt);
+	spin_unlock(&se_global->lu_gps_lock);
+}
+
+/*
+ * Called with t10_alua_lu_gp_member_t->lu_gp_mem_lock
+ */
+void __core_alua_attach_lu_gp_mem(
+	t10_alua_lu_gp_member_t *lu_gp_mem,
+	t10_alua_lu_gp_t *lu_gp)
+{
+	spin_lock(&lu_gp->lu_gp_lock);
+	lu_gp_mem->lu_gp = lu_gp;
+	lu_gp_mem->lu_gp_assoc = 1;
+	list_add_tail(&lu_gp_mem->lu_gp_mem_list, &lu_gp->lu_gp_mem_list);
+	lu_gp->lu_gp_members++;
+	spin_unlock(&lu_gp->lu_gp_lock);
+}
+
+/*
+ * Called with t10_alua_lu_gp_member_t->lu_gp_mem_lock
+ */
+void __core_alua_drop_lu_gp_mem(
+	t10_alua_lu_gp_member_t *lu_gp_mem,
+	t10_alua_lu_gp_t *lu_gp)
+{
+	spin_lock(&lu_gp->lu_gp_lock);
+	list_del(&lu_gp_mem->lu_gp_mem_list);
+	lu_gp_mem->lu_gp = NULL;
+	lu_gp_mem->lu_gp_assoc = 0;
+	lu_gp->lu_gp_members--;
+	spin_unlock(&lu_gp->lu_gp_lock);
+}
+
+t10_alua_tg_pt_gp_t *core_alua_allocate_tg_pt_gp(const char *name)
+{
+	t10_alua_tg_pt_gp_t *tg_pt_gp, *tg_pt_gp_tmp;
+
+	tg_pt_gp = kmem_cache_zalloc(t10_alua_tg_pt_gp_cache, GFP_KERNEL);
+	if (!(tg_pt_gp)) {
+		printk(KERN_ERR "Unable to allocate t10_alua_tg_pt_gp_t\n");
+		return NULL;
+	}
+	INIT_LIST_HEAD(&tg_pt_gp->tg_pt_gp_list);
+	INIT_LIST_HEAD(&tg_pt_gp->tg_pt_gp_mem_list);
+	spin_lock_init(&tg_pt_gp->tg_pt_gp_lock);
+	atomic_set(&tg_pt_gp->tg_pt_gp_ref_cnt, 0);
+	tg_pt_gp->tg_pt_gp_alua_access_state =
+			ALUA_ACCESS_STATE_ACTIVE_OPTMIZED;
+
+	spin_lock(&se_global->tg_pt_gps_lock);
+	if (se_global->alua_tg_pt_gps_count == 0x0000ffff) {
+		spin_unlock(&se_global->tg_pt_gps_lock);
+		kmem_cache_free(t10_alua_tg_pt_gp_cache, tg_pt_gp);
+		return NULL;
+	}
+again:
+	tg_pt_gp->tg_pt_gp_id = se_global->alua_tg_pt_gps_counter++;
+
+	list_for_each_entry(tg_pt_gp_tmp, &se_global->g_tg_pt_gps_list,
+			tg_pt_gp_list) {
+		if (tg_pt_gp_tmp->tg_pt_gp_id == tg_pt_gp->tg_pt_gp_id)
+			goto again;
+	}
+
+	list_add_tail(&tg_pt_gp->tg_pt_gp_list, &se_global->g_tg_pt_gps_list);
+	se_global->alua_tg_pt_gps_count++;
+	spin_unlock(&se_global->tg_pt_gps_lock);
+
+	return tg_pt_gp;
+}
+
+t10_alua_tg_pt_gp_member_t *core_alua_allocate_tg_pt_gp_mem(
+	se_port_t *port)
+{
+	t10_alua_tg_pt_gp_member_t *tg_pt_gp_mem;
+
+	tg_pt_gp_mem = kmem_cache_zalloc(t10_alua_tg_pt_gp_mem_cache,
+				GFP_KERNEL);
+	if (!(tg_pt_gp_mem)) {
+		printk(KERN_ERR "Unable to allocate t10_alua_tg_pt_gp_member_t\n");
+		return ERR_PTR(-ENOMEM);
+	}
+	INIT_LIST_HEAD(&tg_pt_gp_mem->tg_pt_gp_mem_list);
+	spin_lock_init(&tg_pt_gp_mem->tg_pt_gp_mem_lock);
+
+	tg_pt_gp_mem->tg_pt = port;
+	port->sep_alua_tg_pt_gp_mem = tg_pt_gp_mem;
+
+	return tg_pt_gp_mem;
+}
+
+void core_alua_free_tg_pt_gp(t10_alua_tg_pt_gp_t *tg_pt_gp)
+{
+	t10_alua_tg_pt_gp_member_t *tg_pt_gp_mem, *tg_pt_gp_mem_tmp;
+	/*
+	 * Once we have reached this point, config_item_put() has already
+	 * been called from target_core_alua_drop_tg_pt_gp().
+	 *
+	 * Here we remove *tg_pt_gp from the global list so that
+	 * no assications *OR* explict ALUA via SET_TARGET_PORT_GROUPS
+	 * can be made while we are releasing t10_alua_tg_pt_gp_t.
+	 */
+	spin_lock(&se_global->tg_pt_gps_lock);
+	list_del(&tg_pt_gp->tg_pt_gp_list);
+	se_global->alua_tg_pt_gps_counter--;
+	spin_unlock(&se_global->tg_pt_gps_lock);
+	/*
+	 * Allow a t10_alua_tg_pt_gp_member_t * referenced by
+	 * core_alua_get_tg_pt_gp_by_name() in
+	 * target_core_configfs.c:target_core_store_alua_tg_pt_gp()
+	 * to be released with core_alua_put_tg_pt_gp_from_name().
+	 */
+	while (atomic_read(&tg_pt_gp->tg_pt_gp_ref_cnt))
+		msleep(10);
+	/*
+	 * Release reference to t10_alua_tg_pt_gp_t from all associated
+	 * se_port_t.
+	 */
+	spin_lock(&tg_pt_gp->tg_pt_gp_lock);
+	list_for_each_entry_safe(tg_pt_gp_mem, tg_pt_gp_mem_tmp,
+			&tg_pt_gp->tg_pt_gp_mem_list, tg_pt_gp_mem_list) {
+		if (tg_pt_gp_mem->tg_pt_gp_assoc) {
+			list_del(&tg_pt_gp_mem->tg_pt_gp_mem_list);
+			tg_pt_gp->tg_pt_gp_members--;
+			tg_pt_gp_mem->tg_pt_gp_assoc = 0;
+		}
+		spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
+		/*
+		 * tg_pt_gp_mem is assoicated with a single
+		 * se_portt->sep_alua_tg_pt_gp_mem, and is released via
+		 * core_alua_free_tg_pt_gp_mem().
+		 *
+		 * If the passed tg_pt_gp does NOT match the default_tg_pt_gp,
+		 * assume we want to re-assocate a given tg_pt_gp_mem with
+		 * default_tg_pt_gp.
+		 */
+		spin_lock(&tg_pt_gp_mem->tg_pt_gp_mem_lock);
+		if (tg_pt_gp != se_global->default_tg_pt_gp) {
+			__core_alua_attach_tg_pt_gp_mem(tg_pt_gp_mem,
+					se_global->default_tg_pt_gp);
+		} else
+			tg_pt_gp_mem->tg_pt_gp = NULL;
+		spin_unlock(&tg_pt_gp_mem->tg_pt_gp_mem_lock);
+
+		spin_lock(&tg_pt_gp->tg_pt_gp_lock);
+	}
+	spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
+
+	kmem_cache_free(t10_alua_tg_pt_gp_cache, tg_pt_gp);
+}
+
+void core_alua_free_tg_pt_gp_mem(se_port_t *port)
+{
+	se_subsystem_dev_t *su_dev = port->sep_lun->se_dev->se_sub_dev;
+	t10_alua_t *alua = T10_ALUA(su_dev);
+	t10_alua_tg_pt_gp_t *tg_pt_gp;
+	t10_alua_tg_pt_gp_member_t *tg_pt_gp_mem;
+
+	if (alua->alua_type != SPC3_ALUA_EMULATED)
+		return;
+
+	tg_pt_gp_mem = port->sep_alua_tg_pt_gp_mem;
+	if (!(tg_pt_gp_mem))
+		return;
+
+	spin_lock(&tg_pt_gp_mem->tg_pt_gp_mem_lock);
+	tg_pt_gp = tg_pt_gp_mem->tg_pt_gp;
+	if ((tg_pt_gp)) {
+		spin_lock(&tg_pt_gp->tg_pt_gp_lock);
+		if (tg_pt_gp_mem->tg_pt_gp_assoc) {
+			list_del(&tg_pt_gp_mem->tg_pt_gp_mem_list);
+			tg_pt_gp->tg_pt_gp_members--;
+			tg_pt_gp_mem->tg_pt_gp_assoc = 0;
+		}
+		spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
+		tg_pt_gp_mem->tg_pt_gp = NULL;
+	}
+	spin_unlock(&tg_pt_gp_mem->tg_pt_gp_mem_lock);
+
+	kmem_cache_free(t10_alua_tg_pt_gp_mem_cache, tg_pt_gp_mem);
+}
+
+t10_alua_tg_pt_gp_t *core_alua_get_tg_pt_gp_by_name(const char *name)
+{
+	t10_alua_tg_pt_gp_t *tg_pt_gp;
+	struct config_item *ci;
+
+	spin_lock(&se_global->tg_pt_gps_lock);
+	list_for_each_entry(tg_pt_gp, &se_global->g_tg_pt_gps_list,
+			tg_pt_gp_list) {
+		ci = &tg_pt_gp->tg_pt_gp_group.cg_item;
+		if (!(strcmp(config_item_name(ci), name))) {
+			atomic_inc(&tg_pt_gp->tg_pt_gp_ref_cnt);
+			spin_unlock(&se_global->tg_pt_gps_lock);
+			return tg_pt_gp;
+		}
+	}
+	spin_unlock(&se_global->tg_pt_gps_lock);
+
+	return NULL;
+}
+
+void core_alua_put_tg_pt_gp_from_name(t10_alua_tg_pt_gp_t *tg_pt_gp)
+{
+	spin_lock(&se_global->tg_pt_gps_lock);
+	atomic_dec(&tg_pt_gp->tg_pt_gp_ref_cnt);
+	spin_unlock(&se_global->tg_pt_gps_lock);
+}
+
+/*
+ * Called with t10_alua_tg_pt_gp_member_t->tg_pt_gp_mem_lock held
+ */
+void __core_alua_attach_tg_pt_gp_mem(
+	t10_alua_tg_pt_gp_member_t *tg_pt_gp_mem,
+	t10_alua_tg_pt_gp_t *tg_pt_gp)
+{
+	spin_lock(&tg_pt_gp->tg_pt_gp_lock);
+	tg_pt_gp_mem->tg_pt_gp = tg_pt_gp;
+	tg_pt_gp_mem->tg_pt_gp_assoc = 1;
+	list_add_tail(&tg_pt_gp_mem->tg_pt_gp_mem_list,
+			&tg_pt_gp->tg_pt_gp_mem_list);
+	tg_pt_gp->tg_pt_gp_members++;
+	spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
+}
+
+/*
+ * Called with t10_alua_tg_pt_gp_member_t->tg_pt_gp_mem_lock held
+ */
+void __core_alua_drop_tg_pt_gp_mem(
+	t10_alua_tg_pt_gp_member_t *tg_pt_gp_mem,
+	t10_alua_tg_pt_gp_t *tg_pt_gp)
+{
+	spin_lock(&tg_pt_gp->tg_pt_gp_lock);
+	list_del(&tg_pt_gp_mem->tg_pt_gp_mem_list);
+	tg_pt_gp_mem->tg_pt_gp = NULL;
+	tg_pt_gp_mem->tg_pt_gp_assoc = 0;
+	tg_pt_gp->tg_pt_gp_members--;
+	spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
+}
+
+ssize_t core_alua_show_tg_pt_gp_info(se_port_t *port, char *page)
+{
+	se_subsystem_dev_t *su_dev = port->sep_lun->se_dev->se_sub_dev;
+	struct config_item *tg_pt_ci;
+	t10_alua_t *alua = T10_ALUA(su_dev);
+	t10_alua_tg_pt_gp_t *tg_pt_gp;
+	t10_alua_tg_pt_gp_member_t *tg_pt_gp_mem;
+	ssize_t len = 0;
+
+	if (alua->alua_type != SPC3_ALUA_EMULATED)
+		return len;
+
+	tg_pt_gp_mem = port->sep_alua_tg_pt_gp_mem;
+	if (!(tg_pt_gp_mem))
+		return len;
+
+	spin_lock(&tg_pt_gp_mem->tg_pt_gp_mem_lock);
+	tg_pt_gp = tg_pt_gp_mem->tg_pt_gp;
+	if ((tg_pt_gp)) {
+		tg_pt_ci = &tg_pt_gp->tg_pt_gp_group.cg_item;
+		len += sprintf(page, "TG Port Alias: %s\nTG Port Group ID:"
+			" %hu\n", config_item_name(tg_pt_ci),
+			tg_pt_gp->tg_pt_gp_id);
+	}
+	spin_unlock(&tg_pt_gp_mem->tg_pt_gp_mem_lock);
+
+	return len;
+}
+EXPORT_SYMBOL(core_alua_show_tg_pt_gp_info);
+
+ssize_t core_alua_store_tg_pt_gp_info(
+	se_port_t *port,
+	const char *page,
+	size_t count)
+{
+	se_portal_group_t *tpg;
+	se_lun_t *lun;
+	se_subsystem_dev_t *su_dev = port->sep_lun->se_dev->se_sub_dev;
+	t10_alua_tg_pt_gp_t *tg_pt_gp = NULL, *tg_pt_gp_new = NULL;
+	t10_alua_tg_pt_gp_member_t *tg_pt_gp_mem;
+	unsigned char buf[TG_PT_GROUP_NAME_BUF];
+	int move = 0;
+
+	tpg = port->sep_tpg;
+	lun = port->sep_lun;
+
+	if (T10_ALUA(su_dev)->alua_type != SPC3_ALUA_EMULATED) {
+		printk(KERN_WARNING "SPC3_ALUA_EMULATED not enabled for"
+			" %s/tpgt_%hu/%s\n", TPG_TFO(tpg)->tpg_get_wwn(tpg),
+			TPG_TFO(tpg)->tpg_get_tag(tpg),
+			config_item_name(&lun->lun_group.cg_item));
+		return -EINVAL;
+	}
+	if (count > TG_PT_GROUP_NAME_BUF) {
+		printk(KERN_ERR "ALUA Target Port Group alias too large!\n");
+		return -EINVAL;
+	}
+	memset(buf, 0, TG_PT_GROUP_NAME_BUF);
+	memcpy(buf, page, count);
+	/*
+	 * Any ALUA target port group alias besides "NULL" means we will be
+	 * making a new group association.
+	 */
+	if (strcmp(strstrip(buf), "NULL")) {
+		/*
+		 * core_alua_get_tg_pt_gp_by_name() will increment reference to
+		 * t10_alua_tg_pt_gp_t.  This reference is released with
+		 * core_alua_put_tg_pt_gp_from_name() below.
+		 */
+		tg_pt_gp_new = core_alua_get_tg_pt_gp_by_name(strstrip(buf));
+		if (!(tg_pt_gp_new))
+			return -ENODEV;
+	}
+	tg_pt_gp_mem = port->sep_alua_tg_pt_gp_mem;
+	if (!(tg_pt_gp_mem)) {
+		if (tg_pt_gp_new)
+			core_alua_put_tg_pt_gp_from_name(tg_pt_gp_new);
+		printk(KERN_ERR "NULL se_port_t->sep_alua_tg_pt_gp_mem pointer\n");
+		return -EINVAL;
+	}
+
+	spin_lock(&tg_pt_gp_mem->tg_pt_gp_mem_lock);
+	tg_pt_gp = tg_pt_gp_mem->tg_pt_gp;
+	if ((tg_pt_gp)) {
+		/*
+		 * Clearing an existing tg_pt_gp association, and replacing
+		 * with NULL
+		 */
+		if (!(tg_pt_gp_new)) {
+			printk(KERN_INFO "Target_Core_ConfigFS: Releasing"
+				" %s/tpgt_%hu/%s from ALUA Target Port Group:"
+				" core/alua/tg_pt_gps/%s, ID: %hu\n",
+				TPG_TFO(tpg)->tpg_get_wwn(tpg),
+				TPG_TFO(tpg)->tpg_get_tag(tpg),
+				config_item_name(&lun->lun_group.cg_item),
+				config_item_name(
+					&tg_pt_gp->tg_pt_gp_group.cg_item),
+				tg_pt_gp->tg_pt_gp_id);
+
+			__core_alua_drop_tg_pt_gp_mem(tg_pt_gp_mem, tg_pt_gp);
+			spin_unlock(&tg_pt_gp_mem->tg_pt_gp_mem_lock);
+
+			return count;
+		}
+		/*
+		 * Removing existing association of tg_pt_gp_mem with tg_pt_gp
+		 */
+		__core_alua_drop_tg_pt_gp_mem(tg_pt_gp_mem, tg_pt_gp);
+		move = 1;
+	}
+	/*
+	 * Associate tg_pt_gp_mem with tg_pt_gp_new.
+	 */
+	__core_alua_attach_tg_pt_gp_mem(tg_pt_gp_mem, tg_pt_gp_new);
+	spin_unlock(&tg_pt_gp_mem->tg_pt_gp_mem_lock);
+
+	printk("Target_Core_ConfigFS: %s %s/tpgt_%hu/%s to ALUA Target Port"
+		" Group: core/alua/tg_pt_gps/%s, ID: %hu\n", (move) ?
+		"Moving" : "Adding", TPG_TFO(tpg)->tpg_get_wwn(tpg),
+		TPG_TFO(tpg)->tpg_get_tag(tpg),
+		config_item_name(&lun->lun_group.cg_item),
+		config_item_name(&tg_pt_gp_new->tg_pt_gp_group.cg_item),
+		tg_pt_gp_new->tg_pt_gp_id);
+
+	core_alua_put_tg_pt_gp_from_name(tg_pt_gp_new);
+	return count;
+}
+EXPORT_SYMBOL(core_alua_store_tg_pt_gp_info);
+
+int core_setup_alua(se_device_t *dev)
+{
+	se_subsystem_dev_t *su_dev = dev->se_sub_dev;
+	t10_alua_t *alua = T10_ALUA(su_dev);
+	t10_alua_lu_gp_member_t *lu_gp_mem;
+	/*
+	 * If this device is from Target_Core_Mod/pSCSI, use the ALUA logic
+	 * of the Underlying SCSI hardware.  In Linux/SCSI terms, this can
+	 * cause a problem because libata and some SATA RAID HBAs appear
+	 * under Linux/SCSI, but emulate SCSI logic themselves.
+	 */
+	if ((TRANSPORT(dev)->transport_type == TRANSPORT_PLUGIN_PHBA_PDEV) &&
+	    !(DEV_ATTRIB(dev)->emulate_alua)) {
+		alua->alua_type = SPC_ALUA_PASSTHROUGH;
+		printk(KERN_INFO "%s: Using SPC_ALUA_PASSTHROUGH, no ALUA"
+			" emulation\n", TRANSPORT(dev)->name);
+		return 0;
+	}
+	/*
+	 * If SPC-3 or above is reported by real or emulated se_device_t,
+	 * use emulated ALUA.
+	 */
+	if (TRANSPORT(dev)->get_device_rev(dev) >= SCSI_3) {
+		printk(KERN_INFO "%s: Enabling ALUA Emulation for SPC-3"
+			" device\n", TRANSPORT(dev)->name);
+		/*
+		 * Assoicate this se_device_t with the default ALUA
+		 * LUN Group.
+		 */
+		lu_gp_mem = core_alua_allocate_lu_gp_mem(dev);
+		if (IS_ERR(lu_gp_mem) || !lu_gp_mem)
+			return -1;
+
+		alua->alua_type = SPC3_ALUA_EMULATED;
+		spin_lock(&lu_gp_mem->lu_gp_mem_lock);
+		__core_alua_attach_lu_gp_mem(lu_gp_mem,
+				se_global->default_lu_gp);
+		spin_unlock(&lu_gp_mem->lu_gp_mem_lock);
+
+		printk(KERN_INFO "%s: Adding to default ALUA LU Group:"
+			" core/alua/lu_gps/default_lu_gp\n",
+			TRANSPORT(dev)->name);
+	} else {
+		alua->alua_type = SPC2_ALUA_DISABLED;
+		printk("%s: Disabling ALUA Emulation for SPC-2 device\n",
+				TRANSPORT(dev)->name);
+	}
+
+	return 0;
+}
diff --git a/include/target/target_core_alua.h b/include/target/target_core_alua.h
new file mode 100644
index 0000000..468e99b
--- /dev/null
+++ b/include/target/target_core_alua.h
@@ -0,0 +1,71 @@
+#ifndef TARGET_CORE_ALUA_H
+#define TARGET_CORE_ALUA_H
+
+/*
+ * INQUIRY response data, TPGS Field
+ *
+ * from spc4r17 section 6.4.2 Table 135
+ */
+#define TPGS_NO_ALUA				0x00
+#define TPGS_IMPLICT_ALUA			0x10
+#define TPGS_EXPLICT_ALUA			0x20
+#define TPGS_EXPLICT_AND_IMPLICT_ALUA		0x40
+
+/*
+ * ASYMMETRIC ACCESS STATE field
+ *
+ * from spc4r17 section 6.27 Table 245
+ */
+#define ALUA_ACCESS_STATE_ACTIVE_OPTMIZED	0x0
+#define ALUA_ACCESS_STATE_ACTIVE_NON_OPTIMIZED	0x1
+#define ALUA_ACCESS_STATE_STANDBY		0x2
+#define ALUA_ACCESS_STATE_UNAVAILABLE		0x3
+#define ALUA_ACCESS_STATE_OFFLINE		0xe
+#define ALUA_ACCESS_STATE_TRANSITION		0xf
+
+/*
+ * REPORT_TARGET_PORT_GROUP STATUS CODE
+ *
+ * from spc4r17 section 6.27 Table 246
+ */
+#define ALUA_STATUS_NONE				0x00
+#define ALUA_STATUS_ALTERED_BY_EXPLICT_STPG		0x01
+#define ALUA_STATUS_ALTERED_BY_IMPLICT_ALUA		0x02
+
+extern se_global_t *se_global;
+
+extern struct kmem_cache *t10_alua_lu_gp_cache;
+extern struct kmem_cache *t10_alua_lu_gp_mem_cache;
+extern struct kmem_cache *t10_alua_tg_pt_gp_cache;
+extern struct kmem_cache *t10_alua_tg_pt_gp_mem_cache;
+
+extern int core_scsi3_emulate_report_target_port_groups(struct se_cmd_s *);
+extern struct t10_alua_lu_gp_s *core_alua_allocate_lu_gp(const char *);
+extern struct t10_alua_lu_gp_member_s *core_alua_allocate_lu_gp_mem(
+					struct se_device_s *);
+extern void core_alua_free_lu_gp(struct t10_alua_lu_gp_s *);
+extern void core_alua_free_lu_gp_mem(struct se_device_s *);
+extern struct t10_alua_lu_gp_s *core_alua_get_lu_gp_by_name(const char *);
+extern void core_alua_put_lu_gp_from_name(struct t10_alua_lu_gp_s *);
+extern void __core_alua_attach_lu_gp_mem(struct t10_alua_lu_gp_member_s *,
+					struct t10_alua_lu_gp_s *);
+extern void __core_alua_drop_lu_gp_mem(struct t10_alua_lu_gp_member_s *,
+					struct t10_alua_lu_gp_s *);
+extern void core_alua_drop_lu_gp_dev(struct se_device_s *);
+extern struct t10_alua_tg_pt_gp_s *core_alua_allocate_tg_pt_gp(const char *);
+extern struct t10_alua_tg_pt_gp_member_s *core_alua_allocate_tg_pt_gp_mem(
+					struct se_port_s *);
+extern void core_alua_free_tg_pt_gp(struct t10_alua_tg_pt_gp_s *);
+extern void core_alua_free_tg_pt_gp_mem(struct se_port_s *);
+extern struct t10_alua_tg_pt_gp_s *core_alua_get_tg_pt_gp_by_name(const char *);
+extern void core_alua_put_tg_pt_gp_from_name(struct t10_alua_tg_pt_gp_s *);
+extern void __core_alua_attach_tg_pt_gp_mem(struct t10_alua_tg_pt_gp_member_s *,
+					struct t10_alua_tg_pt_gp_s *);
+extern void __core_alua_drop_tg_pt_gp_mem(struct t10_alua_tg_pt_gp_member_s *,
+					struct t10_alua_tg_pt_gp_s *);
+extern ssize_t core_alua_show_tg_pt_gp_info(struct se_port_s *, char *);
+extern ssize_t core_alua_store_tg_pt_gp_info(struct se_port_s *, const char *,
+						size_t);
+extern int core_setup_alua(struct se_device_s *);
+
+#endif /* TARGET_CORE_ALUA_H */



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