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Date: Sun, 25 Jan 2015 05:35:14 -0800
From: Christoph Hellwig <hch@infradead.org>
To: Ming Lei <ming.lei@canonical.com>
Cc: linux-kernel@vger.kernel.org, Dave Kleikamp <dave.kleikamp@oracle.com>,
        Jens Axboe <axboe@kernel.dk>, Zach Brown <zab@zabbo.net>,
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        Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Benjamin LaHaise <bcrl@kvack.org>
Subject: Re: [PATCH v2 3/4] block: loop: introduce 'use_aio' sysfs file
Message-ID: <20150125133514.GC19445@infradead.org>
References: <1421163888-21452-1-git-send-email-ming.lei@canonical.com>
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On Tue, Jan 13, 2015 at 11:44:47PM +0800, Ming Lei wrote:
> So that users can control if kernel aio is used to submit I/O.

Why do you want a sysfs flag for this instead of a flags in ->lo_flags
at setup time?  That's how all other loop-related ABI flags work.