On Sun, Jul 05, 2020 at 03:12:50PM -0600, Jens Axboe wrote:

On 7/5/20 3:09 PM, Matthew Wilcox wrote:

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On Sun, Jul 05, 2020 at 03:00:47PM -0600, Jens Axboe wrote:

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On 7/5/20 12:47 PM, Kanchan Joshi wrote:

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From: Selvakumar S <redacted>

For zone-append, block-layer will return zone-relative offset via ret2
of ki_complete interface. Make changes to collect it, and send to
user-space using cqe->flags.

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I'm surprised you aren't more upset by the abuse of cqe->flags for the
address.

Yeah, it's not great either, but we have less leeway there in terms of
how much space is available to pass back extra data.

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What do you think to my idea of interpreting the user_data as being a
pointer to somewhere to store the address?  Obviously other things
can be stored after the address in the user_data.

I don't like that at all, as all other commands just pass user_data
through. This means the application would have to treat this very
differently, and potentially not have a way to store any data for
locating the original command on the user side.

I think you misunderstood me.  You seem to have thought I meant
"use the user_data field to return the address" when I actually meant
"interpret the user_data field as a pointer to where userspace
wants the address stored".