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/*
* 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);
}
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