summaryrefslogtreecommitdiffstats
path: root/drivers/nvme/host/multipath.c
blob: 956e0b8e9c4d726b9d8d8d1025f04ca75252cbd2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
/*
 * 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, blk_status_t error)
{
	if (!(req->cmd_flags & REQ_NVME_MPATH))
		return false;
	return blk_path_error(error);
}

void nvme_kick_requeue_lists(struct nvme_ctrl *ctrl)
{
	struct nvme_ns *ns;

	down_read(&ctrl->namespaces_rwsem);
	list_for_each_entry(ns, &ctrl->namespaces, list) {
		if (ns->head->disk)
			kblockd_schedule_work(&ns->head->requeue_work);
	}
	up_read(&ctrl->namespaces_rwsem);
}

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 - requeuing 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, NULL);
	if (!q)
		goto out;
	q->queuedata = head;
	blk_queue_make_request(q, nvme_ns_head_make_request);
	q->poll_fn = nvme_ns_head_poll;
	blk_queue_flag_set(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;

	mutex_lock(&head->subsys->lock);
	if (!(head->disk->flags & GENHD_FL_UP)) {
		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);
	}
	mutex_unlock(&head->subsys->lock);
}

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);
}