drivers/nvme/host/multipath.c

   1 /*
   2  * Copyright (c) 2017 Christoph Hellwig.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms and conditions of the GNU General Public License,
   6  * version 2, as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  */
  13
  14 #include <linux/moduleparam.h>
  15 #include "nvme.h"
  16
  17 static bool multipath = true;
  18 module_param(multipath, bool, 0644);
  19 MODULE_PARM_DESC(multipath,
  20         "turn on native support for multiple controllers per subsystem");
  21
  22 void nvme_failover_req(struct request *req)
  23 {
  24         struct nvme_ns *ns = req->q->queuedata;
  25         unsigned long flags;
  26
  27         spin_lock_irqsave(&ns->head->requeue_lock, flags);
  28         blk_steal_bios(&ns->head->requeue_list, req);
  29         spin_unlock_irqrestore(&ns->head->requeue_lock, flags);
  30         blk_mq_end_request(req, 0);
  31
  32         nvme_reset_ctrl(ns->ctrl);
  33         kblockd_schedule_work(&ns->head->requeue_work);
  34 }
  35
  36 bool nvme_req_needs_failover(struct request *req, blk_status_t error)
  37 {
  38         if (!(req->cmd_flags & REQ_NVME_MPATH))
  39                 return false;
  40         return blk_path_error(error);
  41 }
  42
  43 void nvme_kick_requeue_lists(struct nvme_ctrl *ctrl)
  44 {
  45         struct nvme_ns *ns;
  46
  47         down_read(&ctrl->namespaces_rwsem);
  48         list_for_each_entry(ns, &ctrl->namespaces, list) {
  49                 if (ns->head->disk)
  50                         kblockd_schedule_work(&ns->head->requeue_work);
  51         }
  52         up_read(&ctrl->namespaces_rwsem);
  53 }
  54
  55 static struct nvme_ns *__nvme_find_path(struct nvme_ns_head *head)
  56 {
  57         struct nvme_ns *ns;
  58
  59         list_for_each_entry_rcu(ns, &head->list, siblings) {
  60                 if (ns->ctrl->state == NVME_CTRL_LIVE) {
  61                         rcu_assign_pointer(head->current_path, ns);
  62                         return ns;
  63                 }
  64         }
  65
  66         return NULL;
  67 }
  68
  69 inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
  70 {
  71         struct nvme_ns *ns = srcu_dereference(head->current_path, &head->srcu);
  72
  73         if (unlikely(!ns || ns->ctrl->state != NVME_CTRL_LIVE))
  74                 ns = __nvme_find_path(head);
  75         return ns;
  76 }
  77
  78 static blk_qc_t nvme_ns_head_make_request(struct request_queue *q,
  79                 struct bio *bio)
  80 {
  81         struct nvme_ns_head *head = q->queuedata;
  82         struct device *dev = disk_to_dev(head->disk);
  83         struct nvme_ns *ns;
  84         blk_qc_t ret = BLK_QC_T_NONE;
  85         int srcu_idx;
  86
  87         srcu_idx = srcu_read_lock(&head->srcu);
  88         ns = nvme_find_path(head);
  89         if (likely(ns)) {
  90                 bio->bi_disk = ns->disk;
  91                 bio->bi_opf |= REQ_NVME_MPATH;
  92                 ret = direct_make_request(bio);
  93         } else if (!list_empty_careful(&head->list)) {
  94                 dev_warn_ratelimited(dev, "no path available - requeuing I/O\n");
  95
  96                 spin_lock_irq(&head->requeue_lock);
  97                 bio_list_add(&head->requeue_list, bio);
  98                 spin_unlock_irq(&head->requeue_lock);
  99         } else {
 100                 dev_warn_ratelimited(dev, "no path - failing I/O\n");
 101
 102                 bio->bi_status = BLK_STS_IOERR;
 103                 bio_endio(bio);
 104         }
 105
 106         srcu_read_unlock(&head->srcu, srcu_idx);
 107         return ret;
 108 }
 109
 110 static bool nvme_ns_head_poll(struct request_queue *q, blk_qc_t qc)
 111 {
 112         struct nvme_ns_head *head = q->queuedata;
 113         struct nvme_ns *ns;
 114         bool found = false;
 115         int srcu_idx;
 116
 117         srcu_idx = srcu_read_lock(&head->srcu);
 118         ns = srcu_dereference(head->current_path, &head->srcu);
 119         if (likely(ns && ns->ctrl->state == NVME_CTRL_LIVE))
 120                 found = ns->queue->poll_fn(q, qc);
 121         srcu_read_unlock(&head->srcu, srcu_idx);
 122         return found;
 123 }
 124
 125 static void nvme_requeue_work(struct work_struct *work)
 126 {
 127         struct nvme_ns_head *head =
 128                 container_of(work, struct nvme_ns_head, requeue_work);
 129         struct bio *bio, *next;
 130
 131         spin_lock_irq(&head->requeue_lock);
 132         next = bio_list_get(&head->requeue_list);
 133         spin_unlock_irq(&head->requeue_lock);
 134
 135         while ((bio = next) != NULL) {
 136                 next = bio->bi_next;
 137                 bio->bi_next = NULL;
 138
 139                 /*
 140                  * Reset disk to the mpath node and resubmit to select a new
 141                  * path.
 142                  */
 143                 bio->bi_disk = head->disk;
 144                 generic_make_request(bio);
 145         }
 146 }
 147
 148 int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head)
 149 {
 150         struct request_queue *q;
 151         bool vwc = false;
 152
 153         bio_list_init(&head->requeue_list);
 154         spin_lock_init(&head->requeue_lock);
 155         INIT_WORK(&head->requeue_work, nvme_requeue_work);
 156
 157         /*
 158          * Add a multipath node if the subsystems supports multiple controllers.
 159          * We also do this for private namespaces as the namespace sharing data could
 160          * change after a rescan.
 161          */
 162         if (!(ctrl->subsys->cmic & (1 << 1)) || !multipath)
 163                 return 0;
 164
 165         q = blk_alloc_queue_node(GFP_KERNEL, NUMA_NO_NODE, NULL);
 166         if (!q)
 167                 goto out;
 168         q->queuedata = head;
 169         blk_queue_make_request(q, nvme_ns_head_make_request);
 170         q->poll_fn = nvme_ns_head_poll;
 171         blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
 172         /* set to a default value for 512 until disk is validated */
 173         blk_queue_logical_block_size(q, 512);
 174
 175         /* we need to propagate up the VMC settings */
 176         if (ctrl->vwc & NVME_CTRL_VWC_PRESENT)
 177                 vwc = true;
 178         blk_queue_write_cache(q, vwc, vwc);
 179
 180         head->disk = alloc_disk(0);
 181         if (!head->disk)
 182                 goto out_cleanup_queue;
 183         head->disk->fops = &nvme_ns_head_ops;
 184         head->disk->private_data = head;
 185         head->disk->queue = q;
 186         head->disk->flags = GENHD_FL_EXT_DEVT;
 187         sprintf(head->disk->disk_name, "nvme%dn%d",
 188                         ctrl->subsys->instance, head->instance);
 189         return 0;
 190
 191 out_cleanup_queue:
 192         blk_cleanup_queue(q);
 193 out:
 194         return -ENOMEM;
 195 }
 196
 197 void nvme_mpath_add_disk(struct nvme_ns_head *head)
 198 {
 199         if (!head->disk)
 200                 return;
 201
 202         mutex_lock(&head->subsys->lock);
 203         if (!(head->disk->flags & GENHD_FL_UP)) {
 204                 device_add_disk(&head->subsys->dev, head->disk);
 205                 if (sysfs_create_group(&disk_to_dev(head->disk)->kobj,
 206                                 &nvme_ns_id_attr_group))
 207                         pr_warn("%s: failed to create sysfs group for identification\n",
 208                                 head->disk->disk_name);
 209         }
 210         mutex_unlock(&head->subsys->lock);
 211 }
 212
 213 void nvme_mpath_remove_disk(struct nvme_ns_head *head)
 214 {
 215         if (!head->disk)
 216                 return;
 217         sysfs_remove_group(&disk_to_dev(head->disk)->kobj,
 218                            &nvme_ns_id_attr_group);
 219         del_gendisk(head->disk);
 220         blk_set_queue_dying(head->disk->queue);
 221         /* make sure all pending bios are cleaned up */
 222         kblockd_schedule_work(&head->requeue_work);
 223         flush_work(&head->requeue_work);
 224         blk_cleanup_queue(head->disk->queue);
 225         put_disk(head->disk);
 226 }