From 423f49601e2eea96ee4711b590a034b8e098acfc Mon Sep 17 00:00:00 2001
From: David Disseldorp <ddiss@suse.de>
Date: Thu, 27 Aug 2015 17:46:39 +0200
Subject: [PATCH] target/rbd: add pr_clear support
Patch-mainline: Not yet, SES2 clustered LIO/RBD
References: fate#318836

Add a tcm_rbd_pr_ops handler for PR CLEAR requests, that removes any
reservation and all existing registrations.

Signed-off-by: David Disseldorp <ddiss@suse.de>
---
 drivers/target/target_core_rbd.c |  108 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)

--- a/drivers/target/target_core_rbd.c
+++ b/drivers/target/target_core_rbd.c
@@ -2061,6 +2061,113 @@ err_info_free:
 	return ret;
 }
 
+static sense_reason_t
+tcm_rbd_execute_pr_clear(struct se_cmd *cmd, u64 key)
+{
+	struct se_device *dev = cmd->se_dev;
+	struct tcm_rbd_dev *tcm_rbd_dev = TCM_RBD_DEV(dev);
+	char nexus_buf[TCM_RBD_PR_IT_NEXUS_MAXLEN];
+	struct tcm_rbd_pr_info *pr_info;
+	struct tcm_rbd_pr_reg *reg;
+	struct tcm_rbd_pr_reg *existing_reg;
+	char *pr_xattr;
+	int pr_xattr_len;
+	int rc;
+	sense_reason_t ret;
+	int retries = 0;
+
+	if (!cmd->se_sess || !cmd->se_lun) {
+		pr_err("SPC-3 PR: se_sess || struct se_lun is NULL!\n");
+		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+	}
+
+	rc = tcm_rbd_gen_it_nexus(cmd->se_sess, nexus_buf,
+				  ARRAY_SIZE(nexus_buf));
+	if (rc < 0)
+		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+
+retry:
+	pr_info = NULL;
+	pr_xattr = NULL;
+	pr_xattr_len = 0;
+	rc = tcm_rbd_pr_info_get(tcm_rbd_dev, &pr_info, &pr_xattr,
+				 &pr_xattr_len);
+	if (rc < 0) {
+		/* existing registration required for clear */
+		pr_err("failed to obtain PR info\n");
+		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+	}
+
+	/* check for an existing registration */
+	existing_reg = NULL;
+	list_for_each_entry(reg, &pr_info->regs, regs_node) {
+		if (!strncmp(reg->it_nexus, nexus_buf, ARRAY_SIZE(nexus_buf))) {
+			dout("found existing PR reg for %s\n", nexus_buf);
+			existing_reg = reg;
+			break;
+		}
+	}
+
+	if (!existing_reg) {
+		pr_err("SPC-3 PR: Unable to locate registration for CLEAR\n");
+		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+	}
+
+	if (key != existing_reg->key) {
+		pr_err("SPC-3 PR CLEAR: Received res_key: 0x%016Lx"
+			" does not match existing SA REGISTER res_key:"
+			" 0x%016Lx\n", key, existing_reg->key);
+		ret = TCM_RESERVATION_CONFLICT;
+		goto err_info_free;
+	}
+
+	/* release the persistent reservation, if any */
+	if (pr_info->rsv)
+		tcm_rbd_pr_info_rsv_clear(pr_info);
+
+	/* remove all registrations */
+	list_for_each_entry_safe(existing_reg, reg, &pr_info->regs, regs_node) {
+		tcm_rbd_pr_info_clear_reg(pr_info, existing_reg);
+	}
+
+	/*
+	 * TODO:
+	 * e) Establish a unit attention condition for the initiator
+	 *    port associated with every registered I_T nexus other
+	 *    than the I_T nexus on which the PERSISTENT RESERVE OUT
+	 *    command with CLEAR service action was received, with the
+	 *    additional sense code set to RESERVATIONS PREEMPTED.
+	 */
+
+	/* PR generation must be incremented on successful CLEAR */
+	pr_info->gen++;
+
+	rc = tcm_rbd_pr_info_replace(tcm_rbd_dev, pr_xattr, pr_xattr_len,
+				     pr_info);
+	if (rc == -ECANCELED) {
+		pr_warn("atomic PR info update failed due to parallel "
+			"change, expected(%d) %s. Retrying...\n",
+			pr_xattr_len, pr_xattr);
+		retries++;
+		if (retries <= TCM_RBD_PR_REG_MAX_RETRIES) {
+			tcm_rbd_pr_info_free(pr_info);
+			kfree(pr_xattr);
+			goto retry;
+		}
+	}
+	if (rc < 0) {
+		pr_err("atomic PR info update failed: %d\n", rc);
+		ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+		goto err_info_free;
+	}
+
+	ret = TCM_NO_SENSE;
+err_info_free:
+	tcm_rbd_pr_info_free(pr_info);
+	kfree(pr_xattr);
+	return ret;
+}
+
 static struct target_pr_ops tcm_rbd_pr_ops = {
 	.pr_read_keys		= tcm_rbd_execute_pr_read_keys,
 	.pr_read_reservation	= tcm_rbd_execute_pr_read_reservation,
@@ -2068,6 +2175,7 @@ static struct target_pr_ops tcm_rbd_pr_o
 	.pr_register		= tcm_rbd_execute_pr_register,
 	.pr_reserve		= tcm_rbd_execute_pr_reserve,
 	.pr_release		= tcm_rbd_execute_pr_release,
+	.pr_clear		= tcm_rbd_execute_pr_clear,
 };
 
 static const struct target_backend_ops tcm_rbd_ops = {
