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Date:   Wed, 2 Mar 2022 01:59:49 -0800
From:   Christoph Hellwig <hch@infradead.org>
To:     Ming Lei <ming.lei@redhat.com>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        Yu Kuai <yukuai3@huawei.com>
Subject: Re: [PATCH 6/6] blk-mq: manage hctx map via xarray
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On Wed, Mar 02, 2022 at 05:53:44PM +0800, Ming Lei wrote:
> Another point is that 'unsigned long *' is passed to xa_find() as index.
> However, almost all users of queue_for_each_hw_ctx() defines hctx index
> as 'unsigned int'.
> 
> If we switch to xa_for_each(), the type of hctx index needs to be changed
> to 'unsigned long' for every queue_for_each_hw_ctx(). But xa_load()
> needn't such change.
> 
> Also from user viewpoint, looks 'unsigned long' change for hctx index is
> still a bit confusing, IMO.

If you use xarray you need to fit the convention it expects, that should
not be in any way a surprise.