linux-kernel - Re: [PATCH] loop: change fsync to fdatasync when update dio

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Message-ID: <20230126053136.GC28355@lst.de>
Date:   Thu, 26 Jan 2023 06:31:36 +0100
From:   Christoph Hellwig <hch@....de>
To:     Huijin Park <huijin.park@...sung.com>
Cc:     Jens Axboe <axboe@...nel.dk>, Christoph Hellwig <hch@....de>,
        Chaitanya Kulkarni <kch@...dia.com>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        bbanghj.park@...il.com
Subject: Re: [PATCH] loop: change fsync to fdatasync when update dio

On Thu, Jan 26, 2023 at 02:16:57PM +0900, Huijin Park wrote:
> In general, fsync has a larger overhead than fdatasync. And since the
> dio option is for data, it seems like fdatasync is enough.
> So this patch changes it to fdatasync which has little load relatively.

The only difference is that fsync also syncs the timestamps.  So this
change looks correct, but also a bit useless given that buffered to
direct I/O or back changes aren't exactly a fast path.