From: Christoph Hellwig <hch@lst.de>
To: Daniel Wagner <dwagner@suse.de>
Cc: linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
Keith Busch <kbusch@kernel.org>, Christoph Hellwig <hch@lst.de>,
Sagi Grimberg <sagi@grimberg.me>, Hannes Reinecke <hare@suse.de>
Subject: Re: [PATCH v3 4/4] nvme: add csi, ms and nuse to sysfs
Date: Wed, 6 Dec 2023 09:59:45 +0100 [thread overview]
Message-ID: <20231206085945.GC24484@lst.de> (raw)
In-Reply-To: <20231206081244.32733-5-dwagner@suse.de>
On Wed, Dec 06, 2023 at 09:12:44AM +0100, Daniel Wagner wrote:
> libnvme is using the sysfs for enumarating the nvme resources. Though
> there are few missing attritbutes in the sysfs. For these libnvme issues
> commands during discovering.
>
> As the kernel already knows all these attributes and we would like to
> avoid libnvme to issue commands all the time, expose these missing
> attributes.
>
> The nuse value is updated on request because the nuse is a volatile
> value. Since any user can read the sysfs attribute, a very simple rate
> limit is added (update max every 5 seconds). A more sophisticated update
> strategy can be added later if there is actually a need for it.
>
> Signed-off-by: Daniel Wagner <dwagner@suse.de>
> ---
> drivers/nvme/host/core.c | 28 ++++++++++++++++++++++++++++
> drivers/nvme/host/nvme.h | 2 ++
> drivers/nvme/host/sysfs.c | 31 +++++++++++++++++++++++++++++++
> 3 files changed, 61 insertions(+)
>
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index caa52c2f57c8..e7dd64ee1653 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -1663,6 +1663,33 @@ static void nvme_ns_release(struct nvme_ns *ns)
> nvme_put_ns(ns);
> }
>
> +int nvme_ns_update_nuse(struct nvme_ns_head *head)
> +{
> + static DEFINE_RATELIMIT_STATE(_rs, 5 * HZ, 1);
> + struct nvme_id_ns *id;
> + struct nvme_ns *ns;
> + int srcu_idx, ret = -EWOULDBLOCK;
> +
> + if (__ratelimit(&_rs))
> + return 0;
Can you add a comment on the ratelimiting here?
> +
> + srcu_idx = srcu_read_lock(&head->srcu);
> + ns = nvme_find_path(head);
> + if (!ns)
> + goto out_unlock;
> +
> + ret = nvme_identify_ns(ns->ctrl, head->ns_id, &id);
> + if (ret)
> + goto out_unlock;
> +
> + head->nuse = le64_to_cpu(id->nuse);
This looks like the wrong thing to do for the non-multipath nodes,
which should be able to go straight to the ns.
I'd move this to sysfs.c, and then do a similar trick to say
nvme_send_pr_command to directly use the ns for the non-multipath
nodes, and do what you're doing here for the multipath nodes.
> static struct attribute *nvme_ns_id_attrs[] = {
And I duess the _id is not correct now, I'd just drop it.
prev parent reply other threads:[~2023-12-06 8:59 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-06 8:12 [PATCH v3 0/4] nvme: add csi, ms and nuse to sysfs Daniel Wagner
2023-12-06 8:12 ` [PATCH v3 1/4] nvme: lookup ctrl from request instead from namespace Daniel Wagner
2023-12-06 8:12 ` [PATCH v3 2/4] nvme: initialize head before namespace Daniel Wagner
2023-12-06 8:50 ` Christoph Hellwig
2023-12-06 8:12 ` [PATCH v3 3/4] nvme: move ns id info to struct nvme_ns_head Daniel Wagner
2023-12-06 8:54 ` Christoph Hellwig
2023-12-07 10:53 ` Daniel Wagner
2023-12-06 17:38 ` kernel test robot
2023-12-06 17:38 ` kernel test robot
2023-12-07 5:36 ` Dan Carpenter
2023-12-06 8:12 ` [PATCH v3 4/4] nvme: add csi, ms and nuse to sysfs Daniel Wagner
2023-12-06 8:59 ` Christoph Hellwig [this message]
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