[PATCH blktests] nvme/068: add a test for multipath delayed removal

[Nilay Shroff]

> diff --git a/tests/nvme/068 b/tests/nvme/068
> new file mode 100644
> index 0000000..e06fd6b
> --- /dev/null
> +++ b/tests/nvme/068
> @@ -0,0 +1,118 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-3.0+
> +# Copyright (C) 2026 John Garry
> +#
> +# Test NVMe multipath delayed removal works as expected
> +
Should we also reference the commit 62188639ec16 ("nvme-multipath:
introduce delayed removal of the multipath head node") which introduced
this feature in the kernel?

> +. tests/nvme/rc
> +. common/xfs
> +
> +DESCRIPTION="NVMe multipath delayed removal test"
> +QUICK=1
> +
> +requires() {
> +	_nvme_requires
> +	_have_loop
> +	_have_module_param_value nvme_core multipath Y
> +	_require_nvme_trtype_is_fabrics
> +}
> +
> +set_conditions() {
> +	_set_nvme_trtype "$@"
> +}
> +
> +_delayed_nvme_reconnect_ctrl() {
> +	sleep 5
> +	_nvme_connect_subsys
> +}
> +
> +test() {
> +	echo "Running ${TEST_NAME}"
> +
> +	_setup_nvmet
> +
> +	local nvmedev
> +	local ns
> +	local bytes_written
> +	local refcnt_orig
> +	local refcnt
> +	_nvmet_target_setup
> +
> +	_nvme_connect_subsys
> +
> +	# Part a: Prove that writes fail when no path returns. Any reads or
> +	#	  writes are queued during the delayed removal period. If no
> +	#	  paths return before the timer expires, then those IOs should
> +	#	  fail.
> +	#	  During the delayed removal period, ensure that the module
> +	#	  refcnt is incremented, to prove that we cannot remove the
> +	#	  driver during this period.
> +	nvmedev=$(_find_nvme_dev "${def_subsysnqn}")
> +	ns=$(_find_nvme_ns "${def_subsys_uuid}")
> +	refcnt=$(_module_use_count nvme_core)

Should the refcount be stored in $refcnt_orig instead of $refcnt?

> +	echo 10 > "/sys/block/"$ns"/delayed_removal_secs"
> +	refcnt_orig=$(_module_use_count nvme_core)

We may not need to again store refcnt here if we store it
before enabling delayed_removal_sec above.

Other than above trivial comments, this looks good to me.

Thanks,
--Nilay