From: Keith Busch kbusch@kernel.org
[ Upstream commit 1f021341eef41e77a633186e9be5223de2ce5d48 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/nvme/host/multipath.c | 33 +++++++++++++++++++++++++++++++++ drivers/nvme/host/nvme.h | 1 + 2 files changed, 34 insertions(+)
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c index 93ada8941a4c5..43b89c7d585f0 100644 --- a/drivers/nvme/host/multipath.c +++ b/drivers/nvme/host/multipath.c @@ -463,6 +463,20 @@ 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 = @@ -489,6 +503,7 @@ 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. @@ -504,6 +519,16 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head) return -ENOMEM; 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);
@@ -552,6 +577,7 @@ 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); @@ -851,6 +877,12 @@ void nvme_mpath_shutdown_disk(struct nvme_ns_head *head) kblockd_schedule_work(&head->requeue_work); if (test_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); } } @@ -862,6 +894,7 @@ 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); }
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h index 5f8a146b70148..0f49b779dec65 100644 --- a/drivers/nvme/host/nvme.h +++ b/drivers/nvme/host/nvme.h @@ -460,6 +460,7 @@ 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