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Date:   Mon, 4 Dec 2023 08:51:34 +0100
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: [RFC v2 2/3] nvme: move ns id info to struct nvme_ns_head
Message-ID: <20231204075134.GB29377@lst.de>
References: <20231201092735.28592-1-dwagner@suse.de> <20231201092735.28592-3-dwagner@suse.de>
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> +	if (head) {
>  		pr_err_ratelimited("%s: %s(0x%x) @ LBA %llu, %llu blocks, %s (sct 0x%x / sc 0x%x) %s%s\n",
> -		       ns->disk ? ns->disk->disk_name : "?",
> +		       head->disk ? head->disk->disk_name : "?",
>  		       nvme_get_opcode_str(nr->cmd->common.opcode),
>  		       nr->cmd->common.opcode,
> -		       (unsigned long long)nvme_sect_to_lba(ns, blk_rq_pos(req)),
> -		       (unsigned long long)blk_rq_bytes(req) >> ns->lba_shift,
> +		       (unsigned long long)nvme_sect_to_lba(head, blk_rq_pos(req)),

Please avoid the overly long line here.  Best done by removing the pointless
unsigned long long casts, as u64 is always an unsigned long long in the
kernel these days.

> -			u64 slba = nvme_sect_to_lba(ns, bio->bi_iter.bi_sector);
> -			u32 nlb = bio->bi_iter.bi_size >> ns->lba_shift;
> +			u64 slba = nvme_sect_to_lba(head, bio->bi_iter.bi_sector);

Please avoid the overly long line here as well.

> +static void nvme_set_ref_tag(struct nvme_ns_head *head, struct nvme_command *cmnd,

.. and here.  I'm going to stop now, please also fix up all other
places.

>  void nvme_failover_req(struct request *req)
>  {
> -	struct nvme_ns *ns = req->q->queuedata;
> +	struct nvme_ns_head *head = req->q->queuedata;
> +	struct nvme_ctrl *ctrl = nvme_req(req)->ctrl;
> +	struct nvme_ns *ns;
>  	u16 status = nvme_req(req)->status & 0x7ff;
>  	unsigned long flags;
>  	struct bio *bio;
>  
> -	nvme_mpath_clear_current_path(ns);
> +	nvme_mpath_clear_current_path(head);
>  
>  	/*
>  	 * If we got back an ANA error, we know the controller is alive but not
>  	 * ready to serve this namespace.  Kick of a re-read of the ANA
>  	 * information page, and just try any other available path for now.
>  	 */
> -	if (nvme_is_ana_error(status) && ns->ctrl->ana_log_buf) {
> +	if (nvme_is_ana_error(status) && ctrl->ana_log_buf) {
> +		ns = nvme_find_get_ns(ctrl, head->ns_id);

This looks unrelated.

> -bool nvme_mpath_clear_current_path(struct nvme_ns *ns)
> +bool nvme_mpath_clear_current_path(struct nvme_ns_head *head)
>  {
> -	struct nvme_ns_head *head = ns->head;
>  	bool changed = false;
>  	int node;
>  
> @@ -181,7 +183,7 @@ bool nvme_mpath_clear_current_path(struct nvme_ns *ns)
>  		goto out;
>  
>  	for_each_node(node) {
> -		if (ns == rcu_access_pointer(head->current_path[node])) {
> +		if (head == rcu_access_pointer(head->current_path[node])->head) {

and this can't work.  We need to check the actual ns for the path
selection, as that's kindof the point.