linux-ext4 - Re: [PATCH 3/8] nowait aio: return if direct write will trigger writeback

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Date:   Thu, 16 Mar 2017 08:46:31 -0500
From:   Goldwyn Rodrigues <rgoldwyn@...e.de>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     linux-fsdevel@...r.kernel.org, jack@...e.com, hch@...radead.org,
        linux-block@...r.kernel.org, linux-btrfs@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org,
        sagi@...mberg.me, avi@...lladb.com, axboe@...nel.dk,
        linux-api@...r.kernel.org, Goldwyn Rodrigues <rgoldwyn@...e.com>
Subject: Re: [PATCH 3/8] nowait aio: return if direct write will trigger
 writeback



On 03/16/2017 08:20 AM, Matthew Wilcox wrote:
> On Wed, Mar 15, 2017 at 04:51:02PM -0500, Goldwyn Rodrigues wrote:
>> From: Goldwyn Rodrigues <rgoldwyn@...e.com>
>>
>> Find out if the write will trigger a wait due to writeback. If yes,
>> return -EAGAIN.
>>
>> This introduces a new function filemap_range_has_page() which
>> returns true if the file's mapping has a page within the range
>> mentioned.
>>
>> Return -EINVAL for buffered AIO: there are multiple causes of
>> delay such as page locks, dirty throttling logic, page loading
>> from disk etc. which cannot be taken care of.
> 
> Also, this patch only touches the write path; we have a similar call to
> write_and_wait_range() in generic_file_read_iter().
> 

This patch series is concerned with direct-write AIO paths only.

-- 
Goldwyn