Re: [PATCH v7 06/27] libmultipath: Add delayed removal support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Setting `delayed_removal_secs` to 0 via sysfs clears the `MPATH_HEAD_QUEUE_IF_NO_PATH` flag but fails to kick the requeue list, leaving already-queued I/Os stranded indefinitely.
--

commit 751b8b804bd2a99a7fc5d0ec1509ae11a6846846
Author: John Garry <john.garry@linux.dev>
Subject: libmultipath: Add delayed removal support

This commit adds support for delayed removal of multipath devices, similar
to NVMe, to keep the disk and cdev present during intermittent periods with
no available paths. A delayed work callback is utilized to handle the teardown,
and sysfs helpers are exposed for the driver to configure the duration.

> diff --git a/lib/multipath.c b/lib/multipath.c
> index 6b8f6e846987a..fada92bf9754c 100644
> --- a/lib/multipath.c
> +++ b/lib/multipath.c

[ ... ]

> @@ -572,6 +620,47 @@ void mpath_device_set_live(struct mpath_device *mpath_device)
>  }
>  EXPORT_SYMBOL_GPL(mpath_device_set_live);

[ ... ]

> +ssize_t mpath_delayed_removal_secs_store(struct mpath_head *mpath_head,
> +			const char *buf, size_t count)
> +{
> +	unsigned int sec;
> +	ssize_t ret;
> +
> +	ret = kstrtouint(buf, 0, &sec);
> +	if (ret < 0)
> +		return ret;
> +
> +	mutex_lock(&mpath_head->lock);
> +	mpath_head->delayed_removal_secs = sec;
> +	if (sec)
> +		set_bit(MPATH_HEAD_QUEUE_IF_NO_PATH, &mpath_head->flags);
> +	else
> +		clear_bit(MPATH_HEAD_QUEUE_IF_NO_PATH, &mpath_head->flags);
> +	mutex_unlock(&mpath_head->lock);
> +
> +	/*
> +	 * Ensure that update to MPATH_HEAD_QUEUE_IF_NO_PATH is seen
> +	 * by its reader.
> +	 */
> +	mpath_synchronize(mpath_head);
> +
> +	return count;

[Severity: High]
When delayed_removal_secs is set to 0, this clears the
MPATH_HEAD_QUEUE_IF_NO_PATH flag, but does it also need to kick the requeue
list (e.g., via mpath_schedule_requeue_work())?

If there are I/Os already placed in mpath_head->requeue_list during a path
failure while the delay was active, could they remain stranded indefinitely
once the delay is disabled?

> +}
> +EXPORT_SYMBOL_GPL(mpath_delayed_removal_secs_store);

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260901104526.3850621-1-john.g.garry@oracle.com?part=6