--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 Oracle Corporation
+ *
+ * Module Author: Mike Christie
+ */
+#include "dm-path-selector.h"
+
+#include <linux/device-mapper.h>
+#include <linux/module.h>
+
+#define DM_MSG_PREFIX "multipath io-affinity"
+
+struct path_info {
+ struct dm_path *path;
+ cpumask_var_t cpumask;
+ refcount_t refcount;
+ bool failed;
+};
+
+struct selector {
+ struct path_info **path_map;
+ cpumask_var_t path_mask;
+ atomic_t map_misses;
+};
+
+static void ioa_free_path(struct selector *s, unsigned int cpu)
+{
+ struct path_info *pi = s->path_map[cpu];
+
+ if (!pi)
+ return;
+
+ if (refcount_dec_and_test(&pi->refcount)) {
+ cpumask_clear_cpu(cpu, s->path_mask);
+ free_cpumask_var(pi->cpumask);
+ kfree(pi);
+
+ s->path_map[cpu] = NULL;
+ }
+}
+
+static int ioa_add_path(struct path_selector *ps, struct dm_path *path,
+ int argc, char **argv, char **error)
+{
+ struct selector *s = ps->context;
+ struct path_info *pi = NULL;
+ unsigned int cpu;
+ int ret;
+
+ if (argc != 1) {
+ *error = "io-affinity ps: invalid number of arguments";
+ return -EINVAL;
+ }
+
+ pi = kzalloc(sizeof(*pi), GFP_KERNEL);
+ if (!pi) {
+ *error = "io-affinity ps: Error allocating path context";
+ return -ENOMEM;
+ }
+
+ pi->path = path;
+ path->pscontext = pi;
+ refcount_set(&pi->refcount, 1);
+
+ if (!zalloc_cpumask_var(&pi->cpumask, GFP_KERNEL)) {
+ *error = "io-affinity ps: Error allocating cpumask context";
+ ret = -ENOMEM;
+ goto free_pi;
+ }
+
+ ret = cpumask_parse(argv[0], pi->cpumask);
+ if (ret) {
+ *error = "io-affinity ps: invalid cpumask";
+ ret = -EINVAL;
+ goto free_mask;
+ }
+
+ for_each_cpu(cpu, pi->cpumask) {
+ if (cpu >= nr_cpu_ids) {
+ DMWARN_LIMIT("Ignoring mapping for CPU %u. Max CPU is %u",
+ cpu, nr_cpu_ids);
+ break;
+ }
+
+ if (s->path_map[cpu]) {
+ DMWARN("CPU mapping for %u exists. Ignoring.", cpu);
+ continue;
+ }
+
+ cpumask_set_cpu(cpu, s->path_mask);
+ s->path_map[cpu] = pi;
+ refcount_inc(&pi->refcount);
+ continue;
+ }
+
+ if (refcount_dec_and_test(&pi->refcount)) {
+ *error = "io-affinity ps: No new/valid CPU mapping found";
+ ret = -EINVAL;
+ goto free_mask;
+ }
+
+ return 0;
+
+free_mask:
+ free_cpumask_var(pi->cpumask);
+free_pi:
+ kfree(pi);
+ return ret;
+}
+
+static int ioa_create(struct path_selector *ps, unsigned argc, char **argv)
+{
+ struct selector *s;
+
+ s = kmalloc(sizeof(*s), GFP_KERNEL);
+ if (!s)
+ return -ENOMEM;
+
+ s->path_map = kzalloc(nr_cpu_ids * sizeof(struct path_info *),
+ GFP_KERNEL);
+ if (!s->path_map)
+ goto free_selector;
+
+ if (!zalloc_cpumask_var(&s->path_mask, GFP_KERNEL))
+ goto free_map;
+
+ atomic_set(&s->map_misses, 0);
+ ps->context = s;
+ return 0;
+
+free_map:
+ kfree(s->path_map);
+free_selector:
+ kfree(s);
+ return -ENOMEM;
+}
+
+static void ioa_destroy(struct path_selector *ps)
+{
+ struct selector *s = ps->context;
+ unsigned cpu;
+
+ for_each_cpu(cpu, s->path_mask)
+ ioa_free_path(s, cpu);
+
+ free_cpumask_var(s->path_mask);
+ kfree(s->path_map);
+ kfree(s);
+
+ ps->context = NULL;
+}
+
+static int ioa_status(struct path_selector *ps, struct dm_path *path,
+ status_type_t type, char *result, unsigned int maxlen)
+{
+ struct selector *s = ps->context;
+ struct path_info *pi;
+ int sz = 0;
+
+ if (!path) {
+ DMEMIT("0 ");
+ return sz;
+ }
+
+ switch(type) {
+ case STATUSTYPE_INFO:
+ DMEMIT("%d ", atomic_read(&s->map_misses));
+ break;
+ case STATUSTYPE_TABLE:
+ pi = path->pscontext;
+ DMEMIT("%*pb ", cpumask_pr_args(pi->cpumask));
+ break;
+ }
+
+ return sz;
+}
+
+static void ioa_fail_path(struct path_selector *ps, struct dm_path *p)
+{
+ struct path_info *pi = p->pscontext;
+
+ pi->failed = true;
+}
+
+static int ioa_reinstate_path(struct path_selector *ps, struct dm_path *p)
+{
+ struct path_info *pi = p->pscontext;
+
+ pi->failed = false;
+ return 0;
+}
+
+static struct dm_path *ioa_select_path(struct path_selector *ps,
+ size_t nr_bytes)
+{
+ unsigned int cpu, node;
+ struct selector *s = ps->context;
+ const struct cpumask *cpumask;
+ struct path_info *pi;
+ int i;
+
+ cpu = get_cpu();
+
+ pi = s->path_map[cpu];
+ if (pi && !pi->failed)
+ goto done;
+
+ /*
+ * Perf is not optimal, but we at least try the local node then just
+ * try not to fail.
+ */
+ if (!pi)
+ atomic_inc(&s->map_misses);
+
+ node = cpu_to_node(cpu);
+ cpumask = cpumask_of_node(node);
+ for_each_cpu(i, cpumask) {
+ pi = s->path_map[i];
+ if (pi && !pi->failed)
+ goto done;
+ }
+
+ for_each_cpu(i, s->path_mask) {
+ pi = s->path_map[i];
+ if (pi && !pi->failed)
+ goto done;
+ }
+ pi = NULL;
+
+done:
+ put_cpu();
+ return pi ? pi->path : NULL;
+}
+
+static struct path_selector_type ioa_ps = {
+ .name = "io-affinity",
+ .module = THIS_MODULE,
+ .table_args = 1,
+ .info_args = 1,
+ .create = ioa_create,
+ .destroy = ioa_destroy,
+ .status = ioa_status,
+ .add_path = ioa_add_path,
+ .fail_path = ioa_fail_path,
+ .reinstate_path = ioa_reinstate_path,
+ .select_path = ioa_select_path,
+};
+
+static int __init dm_ioa_init(void)
+{
+ int ret = dm_register_path_selector(&ioa_ps);
+
+ if (ret < 0)
+ DMERR("register failed %d", ret);
+ return ret;
+}
+
+static void __exit dm_ioa_exit(void)
+{
+ int ret = dm_unregister_path_selector(&ioa_ps);
+
+ if (ret < 0)
+ DMERR("unregister failed %d", ret);
+}
+
+module_init(dm_ioa_init);
+module_exit(dm_ioa_exit);
+
+MODULE_DESCRIPTION(DM_NAME " multipath path selector that selects paths based on the CPU IO is being executed on");
+MODULE_AUTHOR("Mike Christie <michael.christie@oracle.com>");
+MODULE_LICENSE("GPL");
projects / users / hch / configfs.git / commitdiff