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From:   "Javier =?utf-8?B?R29uesOhbGV6?=" <javier@javigon.com>
Date:   Thu, 18 Jun 2020 10:27:40 +0200
To:     Matias =?utf-8?B?QmrDuHJsaW5n?= <mb@lightnvm.io>
Cc:     Kanchan Joshi <joshi.k@samsung.com>, axboe@kernel.dk,
        viro@zeniv.linux.org.uk, bcrl@kvack.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-aio@kvack.org, io-uring@vger.kernel.org,
        linux-block@vger.kernel.org, selvakuma.s1@samsung.com,
        nj.shetty@samsung.com, Damien Le Moal <Damien.LeMoal@wdc.com>,
        Keith Busch <keith.busch@wdc.com>,
        Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 0/3] zone-append support in aio and io-uring
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On 18.06.2020 10:04, Matias Bjørling wrote:
>On 17/06/2020 19.23, Kanchan Joshi wrote:
>>This patchset enables issuing zone-append using aio and io-uring direct-io interface.
>>
>>For aio, this introduces opcode IOCB_CMD_ZONE_APPEND. Application uses start LBA
>>of the zone to issue append. On completion 'res2' field is used to return
>>zone-relative offset.
>>
>>For io-uring, this introduces three opcodes: IORING_OP_ZONE_APPEND/APPENDV/APPENDV_FIXED.
>>Since io_uring does not have aio-like res2, cqe->flags are repurposed to return zone-relative offset
>
>Please provide a pointers to applications that are updated and ready 
>to take advantage of zone append.

Good point. We are posting a RFC with fio support for append. We wanted
to start the conversation here before.

We can post a fork for improve the reviews in V2.

>
>I do not believe it's beneficial at this point to change the libaio 
>API, applications that would want to use this API, should anyway 
>switch to use io_uring.

I can see why you say this, but isn't it too restrictive to directly
drop libaio support? We can split the patches and merge uring first- no
proble,.

>
>Please also note that applications and libraries that want to take 
>advantage of zone append, can already use the zonefs file-system, as 
>it will use the zone append command when applicable.

Sure. There are different paths available already, which is great. We
have use cases for uring and would like to enable them too.

Thanks,
Javier