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Date:   Sat, 30 Jul 2022 18:22:17 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Eunhee Rho <eunhee83.rho@samsung.com>
Cc:     "chao@kernel.org" <chao@kernel.org>,
        "linux-f2fs-devel@lists.sourceforge.net" 
        <linux-f2fs-devel@lists.sourceforge.net>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v0] f2fs: allow direct read for zoned device
Message-ID: <YuXZSTw4reBDtLgk@google.com>
References: <CGME20220729002517epcms2p35eed262c3349287436c1848ab350c2d4@epcms2p3>
 <20220729002517epcms2p35eed262c3349287436c1848ab350c2d4@epcms2p3>
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In-Reply-To: <20220729002517epcms2p35eed262c3349287436c1848ab350c2d4@epcms2p3>
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On 07/29, Eunhee Rho wrote:
> For zoned devices, f2fs forbids direct IO and forces buffered IO
> to serialize write IOs. However, the constraint does not apply to
> read IOs.
> 
> Signed-off-by: Eunhee Rho <eunhee83.rho@samsung.com>
> ---
>  fs/f2fs/f2fs.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index d0f428aef34b..f69731f17402 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -4471,7 +4471,7 @@ static inline bool f2fs_force_buffered_io(struct inode *inode,
>  	 * for blkzoned device, fallback direct IO to buffered IO, so
>  	 * all IOs can be serialized by log-structured write.
>  	 */
> -	if (f2fs_sb_has_blkzoned(sbi))
> +	if (f2fs_sb_has_blkzoned(sbi) && (rw == WRITE))
>  		return true;

Actually we don't need to check the device type, but rely on the
filesystem allocation policy like the below lfs mode. Can we remove this
line simply?

>  	if (f2fs_lfs_mode(sbi) && (rw == WRITE)) {
>  		if (block_unaligned_IO(inode, iocb, iter))
> -- 
> 2.25.1