[PATCHv3] nvme: correctly account for namespace head reference counter

[Daniel Wagner]

On Thu, Jun 26, 2025 at 10:49:19AM +0530, Nilay Shroff wrote:
> This change prevents stale kobject entries from lingering in sysfs and
> eliminates the module reload failures observed just after running
> nvme/058.
> 
> [1] https://lore.kernel.org/all/CAHj4cs8fOBS-eSjsd5LUBzy7faKXJtgLkCN+mDy_-ezCLLLq+Q@mail.gmail.com/
> 
> Reported-by: yi.zhang at redhat.com
> Closes: https://lore.kernel.org/all/CAHj4cs8fOBS-eSjsd5LUBzy7faKXJtgLkCN+mDy_-ezCLLLq+Q@mail.gmail.com/
> Fixes: 62188639ec16 ("nvme-multipath: introduce delayed removal of the multipath head node")
> Tested-by: yi.zhang at redhat.com
> Signed-off-by: Nilay Shroff <nilay at linux.ibm.com>

Reviewed-by: Daniel Wagner <dwagner at suse.de>

>  		list_del_init(&ns->head->entry);
> +		/*
> +		 * If multipath is not configured, we still create a namespace
> +		 * head (nshead), but head->disk is not initialized in that case.
> +		 * As a result, only a single reference to nshead is held (via
> +		 * kref_init()) when it is created. Therefore, ensure that we
> +		 * do not release the reference to nshead twice if head->disk
> +		 * is not present.
> +		 */
> +		if (ns->head->disk)
> +			last_path = true;

just nitpicking: what about renaming the variable to something like
'multipath' which matches more with the comment.