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Subject: Re: [PATCH v2] eventfd: convert to ->write_iter()
To:     Christoph Hellwig <hch@infradead.org>,
        Michal Kubecek <mkubecek@suse.cz>
Cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
References: <ed4484a3dc8297296bfcd16810f7dc1976d6f7d0.1605808477.git.mkubecek@suse.cz>
 <20201119180315.GB24054@infradead.org>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <ffb060aa-e3ed-3dbe-9418-8ccf8d798974@kernel.dk>
Date:   Thu, 19 Nov 2020 11:48:04 -0700
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On 11/19/20 11:03 AM, Christoph Hellwig wrote:
> On Thu, Nov 19, 2020 at 07:00:19PM +0100, Michal Kubecek wrote:
>> While eventfd ->read() callback was replaced by ->read_iter() recently by
>> commit 12aceb89b0bc ("eventfd: convert to f_op->read_iter()"), ->write()
>> was not replaced.
>>
>> Convert also ->write() to ->write_iter() to make the interface more
>> consistent and allow non-blocking writes from e.g. io_uring. Also
>> reorganize the code and return value handling in a similar way as it was
>> done in eventfd_read().
> 
> But this patch does not allow non-blocking writes.

What am I missing here? He checks the file and IOCB non-block flags,
and returns -EAGAIN if there's no space. If not, it waits and schedules.

-- 
Jens Axboe