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Date: Wed, 17 Jul 2024 14:46:39 -0600
From: Keith Busch <kbusch@kernel.org>
To: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: linux-kernel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
	Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	linux-nvme@lists.infradead.org, Hannes Reinecke <hare@suse.de>,
	Martin Wilck <martin.wilck@suse.com>,
	Ayush Siddarath <ayush.siddarath@dell.com>
Subject: Re: [PATCH v4] nvme_core: scan namespaces asynchronously
Message-ID: <Zpgtr33uqbMogK7c@kbusch-mbp.dhcp.thefacebook.com>
References: <20240717185550.22102-1-stuart.w.hayes@gmail.com>
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In-Reply-To: <20240717185550.22102-1-stuart.w.hayes@gmail.com>

On Wed, Jul 17, 2024 at 01:55:50PM -0500, Stuart Hayes wrote:

Looks good to me. Just one minor comment below.

> @@ -3978,11 +4008,15 @@ static int nvme_scan_ns_list(struct nvme_ctrl *ctrl)
>  	__le32 *ns_list;
>  	u32 prev = 0;
>  	int ret = 0, i;
> +	ASYNC_DOMAIN(domain);
> +	struct async_scan_info scan_info;
>  
>  	ns_list = kzalloc(NVME_IDENTIFY_DATA_SIZE, GFP_KERNEL);
>  	if (!ns_list)
>  		return -ENOMEM;
>  
> +	scan_info.ctrl = ctrl;
> +	scan_info.ns_list = ns_list;
>  	for (;;) {
>  		struct nvme_command cmd = {
>  			.identify.opcode	= nvme_admin_identify,
> @@ -3998,19 +4032,23 @@ static int nvme_scan_ns_list(struct nvme_ctrl *ctrl)
>  			goto free;
>  		}
>  
> +		atomic_set(&scan_info.next_nsid, 0);
>  		for (i = 0; i < nr_entries; i++) {
>  			u32 nsid = le32_to_cpu(ns_list[i]);
>  
>  			if (!nsid)	/* end of the list? */
>  				goto out;
> -			nvme_scan_ns(ctrl, nsid);
> +			async_schedule_domain(nvme_scan_ns_async, &scan_info,
> +						&domain);
>  			while (++prev < nsid)
>  				nvme_ns_remove_by_nsid(ctrl, prev);
>  		}
> +		async_synchronize_full_domain(&domain);
>  	}
>   out:
>  	nvme_remove_invalid_namespaces(ctrl, prev);
>   free:
> +	async_synchronize_full_domain(&domain);

A goto this "free" label appears to mean the async domain has nothing
scheduled, so synchronizing won't be necessary. This should be moved up
tharmlesso the "out" label, I think.

I can change that up when applying; just wanted to mention it in case
I'm missing something.