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Date:   Thu, 23 Mar 2023 16:46:22 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Damien Le Moal <Damien.LeMoal@wdc.com>
Cc:     "hch@infradead.org" <hch@infradead.org>,
        Aravind Ramesh <Aravind.Ramesh@wdc.com>,
        "linux-f2fs-devel@lists.sourceforge.net" 
        <linux-f2fs-devel@lists.sourceforge.net>,
        "hans@owltronix.com" <hans@owltronix.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Hans Holmberg <Hans.Holmberg@wdc.com>,
        "chao@kernel.org" <chao@kernel.org>
Subject: Re: [RFC PATCH] f2fs: preserve direct write semantics when buffering
 is forced
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References: <20230220122004.26555-1-hans.holmberg@wdc.com>
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On 03/23, Damien Le Moal wrote:
> On Thu, 2023-03-23 at 15:14 -0700, Jaegeuk Kim wrote:
> > On 03/20, Christoph Hellwig wrote:
> > > On Mon, Feb 20, 2023 at 01:20:04PM +0100, Hans Holmberg wrote:
> > > > A) Supporting proper direct writes for zoned block devices would
> > > > be the best, but it is currently not supported (probably for
> > > > a good but non-obvious reason). Would it be feasible to
> > > > implement proper direct IO?
> > > 
> > > I don't think why not.? In many ways direct writes to zoned devices
> > > should be easier than non-direct writes.
> > > 
> > > Any comments from the maintainers why the direct I/O writes to
> > > zoned
> > > devices are disabled?? I could not find anything helpful in the
> > > comments
> > > or commit logs.
> > 
> > The direct IO wants to overwrite the data on the same block address,
> > while
> > zoned device does not support it?
> 
> Surely that is not the case with LFS mode, doesn't it ? Otherwise, even
> buffered overwrites would have an issue.

Zoned device only supports LFS mode.

>