linux-ext4 - Re: [PATCH 2/6] ext4: Use i_mutex to serialize unaligned AIO DIO

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Message-ID: <20160309035346.GB3150@thunk.org>
Date:	Tue, 8 Mar 2016 22:53:46 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	Jan Kara <jack@...e.cz>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 2/6] ext4: Use i_mutex to serialize unaligned AIO DIO

On Fri, Feb 19, 2016 at 04:59:38PM +0100, Jan Kara wrote:
> Currently we've used hashed aio_mutex to serialize unaligned AIO DIO.
> However the code cleanups that happened after 2011 when the lock was
> introduced made aio_mutex acquired at almost the same places where we
> already have exclusion using i_mutex. So just use i_mutex for the
> exclusion of unaligned AIO DIO.
> 
> The change moves waiting for pending unwritten extent conversion under
> i_mutex. That makes special handling of O_APPEND writes unnecessary and
> also avoids possible livelocking of unaligned AIO DIO with aligned one
> (nothing was preventing contiguous stream of aligned AIO DIOs to let
> unaligned AIO DIO wait forever).
> 
> Signed-off-by: Jan Kara <jack@...e.cz>

Thanks, applied.

						- Ted
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