This is a note to let you know that I've just added the patch titled
nvme-multipath: defer partition scanning
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nvme-multipath-defer-partition-scanning.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 140c4c128feef40e95909a3e3060156ac6d6d4f4
Author: Keith Busch <kbusch@xxxxxxxxxx>
Date: Tue Oct 15 07:30:17 2024 -0700
nvme-multipath: defer partition scanning
[ 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@xxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 37ea0fa421da8..ede2a14dad8be 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -499,6 +499,20 @@ 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 =
@@ -525,6 +539,7 @@ 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.
@@ -540,6 +555,16 @@ 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);
@@ -589,6 +614,7 @@ 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);
@@ -889,6 +915,12 @@ 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);
}
}
@@ -900,6 +932,7 @@ 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 799f8a2bb0b4f..14a867245c29f 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -476,6 +476,7 @@ 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
