From 4b3c4e992c6ab397b2e56f832b972d57d857583e Mon Sep 17 00:00:00 2001
From: David Disseldorp <ddiss@suse.de>
Date: Fri, 28 Aug 2015 11:09:09 +0200
Subject: [PATCH] target/rbd: add pr_preempt support
Patch-mainline: Not yet, SES2 clustered LIO/RBD
References: fate#318836
Add a tcm_rbd_pr_ops handler for PR PREEMPT requests, that can be used
to remove existing registrations, and/or replace reservations.
Signed-off-by: David Disseldorp <ddiss@suse.de>
---
drivers/target/target_core_rbd.c | 225 +++++++++++++++++++++++++++++++++++++++
1 file changed, 225 insertions(+)
--- a/drivers/target/target_core_rbd.c
+++ b/drivers/target/target_core_rbd.c
@@ -2168,6 +2168,230 @@ err_info_free:
return ret;
}
+static int
+tcm_rbd_pr_info_rm_regs_key(struct tcm_rbd_pr_info *pr_info,
+ struct tcm_rbd_pr_reg *existing_reg,
+ u64 new_key)
+{
+ struct tcm_rbd_pr_reg *reg;
+ struct tcm_rbd_pr_reg *reg_n;
+ bool found = false;
+
+ if (new_key == 0) {
+ dout("removing all non-nexus regs\n");
+ }
+
+ list_for_each_entry_safe(reg, reg_n, &pr_info->regs, regs_node) {
+ if (reg == existing_reg)
+ continue;
+
+ if (new_key && (reg->key != new_key))
+ continue;
+
+ tcm_rbd_pr_info_clear_reg(pr_info, reg);
+ found = true;
+
+ /* TODO flag UA if different IT nexus */
+ }
+
+ if (!found) {
+ return -ENOENT;
+ }
+
+ return 0;
+}
+
+/*
+ * Preempt logic is pretty complex. This implementation attempts to resemble
+ * SPC4r37 Figure 9 — Device server interpretation of PREEMPT service action.
+ */
+static sense_reason_t
+tcm_rbd_execute_pr_preempt(struct se_cmd *cmd, u64 old_key, u64 new_key,
+ int type, bool abort)
+{
+ 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_rsv *rsv;
+ struct tcm_rbd_pr_reg *reg;
+ struct tcm_rbd_pr_reg *existing_reg;
+ bool all_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;
+ }
+
+ if (abort) {
+ pr_err("PR PREEMPT AND ABORT not supported by RBD backend\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;
+ all_reg = false;
+ rc = tcm_rbd_pr_info_get(tcm_rbd_dev, &pr_info, &pr_xattr,
+ &pr_xattr_len);
+ if (rc == -ENODATA) {
+ pr_err("SPC-3 PR: no registrations for PREEMPT\n");
+ return TCM_RESERVATION_CONFLICT;
+ } else if (rc < 0) {
+ 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 PREEMPT\n");
+ ret = TCM_RESERVATION_CONFLICT;
+ goto err_info_free;
+ }
+
+ if (old_key != existing_reg->key) {
+ pr_err("SPC-3 PR PREEMPT: Received res_key: 0x%016Lx"
+ " does not match existing SA REGISTER res_key:"
+ " 0x%016Lx\n", old_key, existing_reg->key);
+ ret = TCM_RESERVATION_CONFLICT;
+ goto err_info_free;
+ }
+
+ if (!pr_info->rsv) {
+ /* no reservation, remove regs indicated by new_key */
+ if (new_key == 0) {
+ ret = TCM_INVALID_PARAMETER_LIST;
+ goto err_info_free;
+ }
+ rc = tcm_rbd_pr_info_rm_regs_key(pr_info, existing_reg,
+ new_key);
+ if (rc == -ENOENT) {
+ ret = TCM_RESERVATION_CONFLICT;
+ goto err_info_free;
+ } else if (rc < 0) {
+ ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+ goto err_info_free;
+ }
+ goto commit;
+ }
+
+
+ rsv = pr_info->rsv;
+ if ((rsv->type == PR_TYPE_WRITE_EXCLUSIVE_ALLREG)
+ || (rsv->type == PR_TYPE_EXCLUSIVE_ACCESS_ALLREG)) {
+ all_reg = true;
+ }
+
+ if (all_reg) {
+ /* if key is zero, then remove all non-nexus regs */
+ rc = tcm_rbd_pr_info_rm_regs_key(pr_info, existing_reg,
+ new_key);
+ if (rc == -ENOENT) {
+ ret = TCM_RESERVATION_CONFLICT;
+ goto err_info_free;
+ } else if (rc < 0) {
+ ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+ goto err_info_free;
+ }
+
+ if (new_key == 0) {
+ tcm_rbd_pr_info_rsv_clear(pr_info);
+ rsv = NULL;
+ rc = tcm_rbd_pr_info_rsv_set(pr_info, existing_reg->key,
+ existing_reg->it_nexus, type);
+ if (rc < 0) {
+ pr_err("failed to set PR info reservation\n");
+ ret = TCM_OUT_OF_RESOURCES;
+ goto err_info_free;
+ }
+ }
+ goto commit;
+ }
+
+ if (rsv->key != new_key) {
+ if (new_key == 0) {
+ ret = TCM_INVALID_PARAMETER_LIST;
+ goto err_info_free;
+ }
+ rc = tcm_rbd_pr_info_rm_regs_key(pr_info, existing_reg,
+ new_key);
+ if (rc == -ENOENT) {
+ ret = TCM_RESERVATION_CONFLICT;
+ goto err_info_free;
+ } else if (rc < 0) {
+ ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+ goto err_info_free;
+ }
+ goto commit;
+ }
+
+ rc = tcm_rbd_pr_info_rm_regs_key(pr_info, existing_reg, new_key);
+ if (rc == -ENOENT) {
+ ret = TCM_RESERVATION_CONFLICT;
+ goto err_info_free;
+ } else if (rc < 0) {
+ ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+ goto err_info_free;
+ }
+ tcm_rbd_pr_info_rsv_clear(pr_info);
+ rsv = NULL;
+ rc = tcm_rbd_pr_info_rsv_set(pr_info, existing_reg->key,
+ existing_reg->it_nexus, type);
+ if (rc < 0) {
+ pr_err("failed to set PR info reservation\n");
+ ret = TCM_OUT_OF_RESOURCES;
+ goto err_info_free;
+ }
+commit:
+ /* PR generation must be incremented on successful PREEMPT */
+ 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,
@@ -2176,6 +2400,7 @@ static struct target_pr_ops tcm_rbd_pr_o
.pr_reserve = tcm_rbd_execute_pr_reserve,
.pr_release = tcm_rbd_execute_pr_release,
.pr_clear = tcm_rbd_execute_pr_clear,
+ .pr_preempt = tcm_rbd_execute_pr_preempt,
};
static const struct target_backend_ops tcm_rbd_ops = {