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Wed, 08 Jul 2020 07:59:51 -0700 (PDT) Subject: Re: [PATCH v3 4/4] io_uring: add support for zone-append To: Matthew Wilcox Cc: Kanchan Joshi , viro@zeniv.linux.org.uk, bcrl@kvack.org, hch@infradead.org, Damien.LeMoal@wdc.com, asml.silence@gmail.com, linux-fsdevel@vger.kernel.org, mb@lightnvm.io, linux-kernel@vger.kernel.org, linux-aio@kvack.org, io-uring@vger.kernel.org, linux-block@vger.kernel.org, Selvakumar S , Nitesh Shetty , Javier Gonzalez References: <20200706143208.GA25523@casper.infradead.org> <20200707151105.GA23395@test-zns> <20200707155237.GM25523@casper.infradead.org> <20200707202342.GA28364@test-zns> <7a44d9c6-bf7d-0666-fc29-32c3cba9d1d8@kernel.dk> <20200707221812.GN25523@casper.infradead.org> <145cc0ad-af86-2d6a-78b3-9ade007aae52@kernel.dk> <20200708125805.GA16495@test-zns> <2962cd68-de34-89be-0464-8b102a3f1d0e@kernel.dk> <20200708145826.GS25523@casper.infradead.org> From: Jens Axboe Message-ID: Date: Wed, 8 Jul 2020 08:59:50 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200708145826.GS25523@casper.infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 7/8/20 8:58 AM, Matthew Wilcox wrote: > On Wed, Jul 08, 2020 at 08:54:07AM -0600, Jens Axboe wrote: >> On 7/8/20 6:58 AM, Kanchan Joshi wrote: >>>>> +#define IOCB_NO_CMPL (15 << 28) >>>>> >>>>> struct kiocb { >>>>> [...] >>>>> - void (*ki_complete)(struct kiocb *iocb, long ret, long ret2); >>>>> + loff_t __user *ki_uposp; >>>>> - int ki_flags; >>>>> + unsigned int ki_flags; >>>>> >>>>> +typedef void ki_cmpl(struct kiocb *, long ret, long ret2); >>>>> +static ki_cmpl * const ki_cmpls[15]; >>>>> >>>>> +void ki_complete(struct kiocb *iocb, long ret, long ret2) >>>>> +{ >>>>> + unsigned int id = iocb->ki_flags >> 28; >>>>> + >>>>> + if (id < 15) >>>>> + ki_cmpls[id](iocb, ret, ret2); >>>>> +} >>>>> >>>>> +int kiocb_cmpl_register(void (*cb)(struct kiocb *, long, long)) >>>>> +{ >>>>> + for (i = 0; i < 15; i++) { >>>>> + if (ki_cmpls[id]) >>>>> + continue; >>>>> + ki_cmpls[id] = cb; >>>>> + return id; >>>>> + } >>>>> + WARN(); >>>>> + return -1; >>>>> +} >>>> >>>> That could work, we don't really have a lot of different completion >>>> types in the kernel. >>> >>> Thanks, this looks sorted. >> >> Not really, someone still needs to do that work. I took a quick look, and >> most of it looks straight forward. The only potential complication is >> ocfs2, which does a swap of the completion for the kiocb. That would just >> turn into an upper flag swap. And potential sync kiocb with NULL >> ki_complete. The latter should be fine, I think we just need to reserve >> completion nr 0 for being that. > > I was reserving completion 15 for that ;-) > > +#define IOCB_NO_CMPL (15 << 28) > ... > + if (id < 15) > + ki_cmpls[id](iocb, ret, ret2); > > Saves us one pointer in the array ... That works. Are you going to turn this into an actual series of patches, adding the functionality and converting users? -- Jens Axboe