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nvme-multipath: defer partition scanning

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We need to suppress the partition scan from occuring within the
controller's scan_work context. If a path error occurs here, the IO will
wait until a path becomes available or all paths are torn down, but that
action also occurs within scan_work, so it would deadlock. Defer the
partion scan to a different context that does not block scan_work.

Reported-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
This commit is contained in:
Keith Busch 2024-10-15 07:30:17 -07:00
parent 0ce96a6708
commit 1f021341ee
2 changed files with 34 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
drivers/nvme/host/multipath.c
View File

@ -579,6 +579,20 @@ static int nvme_add_ns_head_cdev(struct nvme_ns_head *head)
return ret;
}
static void nvme_partition_scan_work(struct work_struct *work)
{
struct nvme_ns_head *head =
container_of(work, struct nvme_ns_head, partition_scan_work);
if (WARN_ON_ONCE(!test_and_clear_bit(GD_SUPPRESS_PART_SCAN,
&head->disk->state)))
return;
mutex_lock(&head->disk->open_mutex);
bdev_disk_changed(head->disk, false);
mutex_unlock(&head->disk->open_mutex);
}
static void nvme_requeue_work(struct work_struct *work)
{
struct nvme_ns_head *head =
@ -605,6 +619,7 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head)
bio_list_init(&head->requeue_list);
spin_lock_init(&head->requeue_lock);
INIT_WORK(&head->requeue_work, nvme_requeue_work);
INIT_WORK(&head->partition_scan_work, nvme_partition_scan_work);
/*
* Add a multipath node if the subsystems supports multiple controllers.
@ -628,6 +643,16 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head)
return PTR_ERR(head->disk);
head->disk->fops = &nvme_ns_head_ops;
head->disk->private_data = head;
/*
* We need to suppress the partition scan from occuring within the
* controller's scan_work context. If a path error occurs here, the IO
* will wait until a path becomes available or all paths are torn down,
* but that action also occurs within scan_work, so it would deadlock.
* Defer the partion scan to a different context that does not block
* scan_work.
*/
set_bit(GD_SUPPRESS_PART_SCAN, &head->disk->state);
sprintf(head->disk->disk_name, "nvme%dn%d",
ctrl->subsys->instance, head->instance);
return 0;
@ -654,6 +679,7 @@ static void nvme_mpath_set_live(struct nvme_ns *ns)
return;
}
nvme_add_ns_head_cdev(head);
kblockd_schedule_work(&head->partition_scan_work);
}
mutex_lock(&head->lock);
@ -973,14 +999,14 @@ void nvme_mpath_shutdown_disk(struct nvme_ns_head *head)
return;
if (test_and_clear_bit(NVME_NSHEAD_DISK_LIVE, &head->flags)) {
nvme_cdev_del(&head->cdev, &head->cdev_device);
/*
* requeue I/O after NVME_NSHEAD_DISK_LIVE has been cleared
* to allow multipath to fail all I/O.
*/
synchronize_srcu(&head->srcu);
kblockd_schedule_work(&head->requeue_work);
del_gendisk(head->disk);
}
/*
* requeue I/O after NVME_NSHEAD_DISK_LIVE has been cleared
* to allow multipath to fail all I/O.
*/
synchronize_srcu(&head->srcu);
kblockd_schedule_work(&head->requeue_work);
}
void nvme_mpath_remove_disk(struct nvme_ns_head *head)
@ -990,6 +1016,7 @@ void nvme_mpath_remove_disk(struct nvme_ns_head *head)
/* make sure all pending bios are cleaned up */
kblockd_schedule_work(&head->requeue_work);
flush_work(&head->requeue_work);
flush_work(&head->partition_scan_work);
put_disk(head->disk);
}

1
drivers/nvme/host/nvme.h
View File

@ -494,6 +494,7 @@ struct nvme_ns_head {
struct bio_list requeue_list;
spinlock_t requeue_lock;
struct work_struct requeue_work;
struct work_struct partition_scan_work;
struct mutex lock;
unsigned long flags;
#define NVME_NSHEAD_DISK_LIVE 0