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-rw-r--r--drivers/nvme/host/multipath.c291
1 files changed, 291 insertions, 0 deletions
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
new file mode 100644
index 000000000000..78d92151a904
--- /dev/null
+++ b/drivers/nvme/host/multipath.c
@@ -0,0 +1,291 @@
+/*
+ * Copyright (c) 2017 Christoph Hellwig.
+ *
+ * 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.
+ */
+
+#include <linux/moduleparam.h>
+#include "nvme.h"
+
+static bool multipath = true;
+module_param(multipath, bool, 0644);
+MODULE_PARM_DESC(multipath,
+ "turn on native support for multiple controllers per subsystem");
+
+void nvme_failover_req(struct request *req)
+{
+ struct nvme_ns *ns = req->q->queuedata;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ns->head->requeue_lock, flags);
+ blk_steal_bios(&ns->head->requeue_list, req);
+ spin_unlock_irqrestore(&ns->head->requeue_lock, flags);
+ blk_mq_end_request(req, 0);
+
+ nvme_reset_ctrl(ns->ctrl);
+ kblockd_schedule_work(&ns->head->requeue_work);
+}
+
+bool nvme_req_needs_failover(struct request *req)
+{
+ if (!(req->cmd_flags & REQ_NVME_MPATH))
+ return false;
+
+ switch (nvme_req(req)->status & 0x7ff) {
+ /*
+ * Generic command status:
+ */
+ case NVME_SC_INVALID_OPCODE:
+ case NVME_SC_INVALID_FIELD:
+ case NVME_SC_INVALID_NS:
+ case NVME_SC_LBA_RANGE:
+ case NVME_SC_CAP_EXCEEDED:
+ case NVME_SC_RESERVATION_CONFLICT:
+ return false;
+
+ /*
+ * I/O command set specific error. Unfortunately these values are
+ * reused for fabrics commands, but those should never get here.
+ */
+ case NVME_SC_BAD_ATTRIBUTES:
+ case NVME_SC_INVALID_PI:
+ case NVME_SC_READ_ONLY:
+ case NVME_SC_ONCS_NOT_SUPPORTED:
+ WARN_ON_ONCE(nvme_req(req)->cmd->common.opcode ==
+ nvme_fabrics_command);
+ return false;
+
+ /*
+ * Media and Data Integrity Errors:
+ */
+ case NVME_SC_WRITE_FAULT:
+ case NVME_SC_READ_ERROR:
+ case NVME_SC_GUARD_CHECK:
+ case NVME_SC_APPTAG_CHECK:
+ case NVME_SC_REFTAG_CHECK:
+ case NVME_SC_COMPARE_FAILED:
+ case NVME_SC_ACCESS_DENIED:
+ case NVME_SC_UNWRITTEN_BLOCK:
+ return false;
+ }
+
+ /* Everything else could be a path failure, so should be retried */
+ return true;
+}
+
+void nvme_kick_requeue_lists(struct nvme_ctrl *ctrl)
+{
+ struct nvme_ns *ns;
+
+ mutex_lock(&ctrl->namespaces_mutex);
+ list_for_each_entry(ns, &ctrl->namespaces, list) {
+ if (ns->head->disk)
+ kblockd_schedule_work(&ns->head->requeue_work);
+ }
+ mutex_unlock(&ctrl->namespaces_mutex);
+}
+
+static struct nvme_ns *__nvme_find_path(struct nvme_ns_head *head)
+{
+ struct nvme_ns *ns;
+
+ list_for_each_entry_rcu(ns, &head->list, siblings) {
+ if (ns->ctrl->state == NVME_CTRL_LIVE) {
+ rcu_assign_pointer(head->current_path, ns);
+ return ns;
+ }
+ }
+
+ return NULL;
+}
+
+inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
+{
+ struct nvme_ns *ns = srcu_dereference(head->current_path, &head->srcu);
+
+ if (unlikely(!ns || ns->ctrl->state != NVME_CTRL_LIVE))
+ ns = __nvme_find_path(head);
+ return ns;
+}
+
+static blk_qc_t nvme_ns_head_make_request(struct request_queue *q,
+ struct bio *bio)
+{
+ struct nvme_ns_head *head = q->queuedata;
+ struct device *dev = disk_to_dev(head->disk);
+ struct nvme_ns *ns;
+ blk_qc_t ret = BLK_QC_T_NONE;
+ int srcu_idx;
+
+ srcu_idx = srcu_read_lock(&head->srcu);
+ ns = nvme_find_path(head);
+ if (likely(ns)) {
+ bio->bi_disk = ns->disk;
+ bio->bi_opf |= REQ_NVME_MPATH;
+ ret = direct_make_request(bio);
+ } else if (!list_empty_careful(&head->list)) {
+ dev_warn_ratelimited(dev, "no path available - requeing I/O\n");
+
+ spin_lock_irq(&head->requeue_lock);
+ bio_list_add(&head->requeue_list, bio);
+ spin_unlock_irq(&head->requeue_lock);
+ } else {
+ dev_warn_ratelimited(dev, "no path - failing I/O\n");
+
+ bio->bi_status = BLK_STS_IOERR;
+ bio_endio(bio);
+ }
+
+ srcu_read_unlock(&head->srcu, srcu_idx);
+ return ret;
+}
+
+static bool nvme_ns_head_poll(struct request_queue *q, blk_qc_t qc)
+{
+ struct nvme_ns_head *head = q->queuedata;
+ struct nvme_ns *ns;
+ bool found = false;
+ int srcu_idx;
+
+ srcu_idx = srcu_read_lock(&head->srcu);
+ ns = srcu_dereference(head->current_path, &head->srcu);
+ if (likely(ns && ns->ctrl->state == NVME_CTRL_LIVE))
+ found = ns->queue->poll_fn(q, qc);
+ srcu_read_unlock(&head->srcu, srcu_idx);
+ return found;
+}
+
+static void nvme_requeue_work(struct work_struct *work)
+{
+ struct nvme_ns_head *head =
+ container_of(work, struct nvme_ns_head, requeue_work);
+ struct bio *bio, *next;
+
+ spin_lock_irq(&head->requeue_lock);
+ next = bio_list_get(&head->requeue_list);
+ spin_unlock_irq(&head->requeue_lock);
+
+ while ((bio = next) != NULL) {
+ next = bio->bi_next;
+ bio->bi_next = NULL;
+
+ /*
+ * Reset disk to the mpath node and resubmit to select a new
+ * path.
+ */
+ bio->bi_disk = head->disk;
+ generic_make_request(bio);
+ }
+}
+
+int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head)
+{
+ struct request_queue *q;
+ bool vwc = false;
+
+ bio_list_init(&head->requeue_list);
+ spin_lock_init(&head->requeue_lock);
+ INIT_WORK(&head->requeue_work, nvme_requeue_work);
+
+ /*
+ * Add a multipath node if the subsystems supports multiple controllers.
+ * We also do this for private namespaces as the namespace sharing data could
+ * change after a rescan.
+ */
+ if (!(ctrl->subsys->cmic & (1 << 1)) || !multipath)
+ return 0;
+
+ q = blk_alloc_queue_node(GFP_KERNEL, NUMA_NO_NODE);
+ if (!q)
+ goto out;
+ q->queuedata = head;
+ blk_queue_make_request(q, nvme_ns_head_make_request);
+ q->poll_fn = nvme_ns_head_poll;
+ queue_flag_set_unlocked(QUEUE_FLAG_NONROT, q);
+ /* set to a default value for 512 until disk is validated */
+ blk_queue_logical_block_size(q, 512);
+
+ /* we need to propagate up the VMC settings */
+ if (ctrl->vwc & NVME_CTRL_VWC_PRESENT)
+ vwc = true;
+ blk_queue_write_cache(q, vwc, vwc);
+
+ head->disk = alloc_disk(0);
+ if (!head->disk)
+ goto out_cleanup_queue;
+ head->disk->fops = &nvme_ns_head_ops;
+ head->disk->private_data = head;
+ head->disk->queue = q;
+ head->disk->flags = GENHD_FL_EXT_DEVT;
+ sprintf(head->disk->disk_name, "nvme%dn%d",
+ ctrl->subsys->instance, head->instance);
+ return 0;
+
+out_cleanup_queue:
+ blk_cleanup_queue(q);
+out:
+ return -ENOMEM;
+}
+
+void nvme_mpath_add_disk(struct nvme_ns_head *head)
+{
+ if (!head->disk)
+ return;
+ device_add_disk(&head->subsys->dev, head->disk);
+ if (sysfs_create_group(&disk_to_dev(head->disk)->kobj,
+ &nvme_ns_id_attr_group))
+ pr_warn("%s: failed to create sysfs group for identification\n",
+ head->disk->disk_name);
+}
+
+void nvme_mpath_add_disk_links(struct nvme_ns *ns)
+{
+ struct kobject *slave_disk_kobj, *holder_disk_kobj;
+
+ if (!ns->head->disk)
+ return;
+
+ slave_disk_kobj = &disk_to_dev(ns->disk)->kobj;
+ if (sysfs_create_link(ns->head->disk->slave_dir, slave_disk_kobj,
+ kobject_name(slave_disk_kobj)))
+ return;
+
+ holder_disk_kobj = &disk_to_dev(ns->head->disk)->kobj;
+ if (sysfs_create_link(ns->disk->part0.holder_dir, holder_disk_kobj,
+ kobject_name(holder_disk_kobj)))
+ sysfs_remove_link(ns->head->disk->slave_dir,
+ kobject_name(slave_disk_kobj));
+}
+
+void nvme_mpath_remove_disk(struct nvme_ns_head *head)
+{
+ if (!head->disk)
+ return;
+ sysfs_remove_group(&disk_to_dev(head->disk)->kobj,
+ &nvme_ns_id_attr_group);
+ del_gendisk(head->disk);
+ blk_set_queue_dying(head->disk->queue);
+ /* make sure all pending bios are cleaned up */
+ kblockd_schedule_work(&head->requeue_work);
+ flush_work(&head->requeue_work);
+ blk_cleanup_queue(head->disk->queue);
+ put_disk(head->disk);
+}
+
+void nvme_mpath_remove_disk_links(struct nvme_ns *ns)
+{
+ if (!ns->head->disk)
+ return;
+
+ sysfs_remove_link(ns->disk->part0.holder_dir,
+ kobject_name(&disk_to_dev(ns->head->disk)->kobj));
+ sysfs_remove_link(ns->head->disk->slave_dir,
+ kobject_name(&disk_to_dev(ns->disk)->kobj));
+}