linux-kernel - Re: [PATCH V2] exfat: fdatasync flag should be same like generic_write

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Message-ID:
 <PUZPR04MB631659A25F27D1F0957E78A6817DA@PUZPR04MB6316.apcprd04.prod.outlook.com>
Date: Thu, 19 Jun 2025 09:34:08 +0000
From: "Yuezhang.Mo@...y.com" <Yuezhang.Mo@...y.com>
To: Zhengxu Zhang <zhengxu.zhang@...soc.com>,
        "linkinjeon@...nel.org"
	<linkinjeon@...nel.org>,
        "sj1557.seo@...sung.com" <sj1557.seo@...sung.com>
CC: "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "cixi.geng@...ux.dev" <cixi.geng@...ux.dev>,
        "hao_hao.wang@...soc.com"
	<hao_hao.wang@...soc.com>,
        "zhiguo.niu@...soc.com" <zhiguo.niu@...soc.com>
Subject: Re: [PATCH V2] exfat: fdatasync flag should be same like
 generic_write_sync()

> Test: androbench by default setting, use 64GB sdcard.
>  the random write speed:
>         without this patch 3.5MB/s
>         with this patch 7MB/s
> 
> After patch "11a347fb6cef", the random write speed decreased significantly.
> the .write_iter() interface had been modified, and check the differences with
> generic_file_write_iter(), when calling generic_write_sync() and
> exfat_file_write_iter() to call vfs_fsync_range(), the fdatasync flag is wrong,
> and make not use the fdatasync mode, and make random write speed decreased.
> 
> So use generic_write_sync() instead of vfs_fsync_range().
> 
> Fixes: 11a347fb6cef ("exfat: change to get file size from DataLength")
> 
> Signed-off-by: Zhengxu Zhang <zhengxu.zhang@...soc.com>
> ---
>  fs/exfat/file.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/exfat/file.c b/fs/exfat/file.c
> index 841a5b18e3df..7ac5126aa4f1 100644
> --- a/fs/exfat/file.c
> +++ b/fs/exfat/file.c
> @@ -623,9 +623,8 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter)
>         if (pos > valid_size)
>                 pos = valid_size;
> 
> -       if (iocb_is_dsync(iocb) && iocb->ki_pos > pos) {
> -               ssize_t err = vfs_fsync_range(file, pos, iocb->ki_pos - 1,
> -                               iocb->ki_flags & IOCB_SYNC);
> +       if (iocb->ki_pos > pos) {
> +               ssize_t err = generic_write_sync(iocb, iocb->ki_pos - pos);
>                 if (err < 0)
>                         return err;
>         }

It's good to me.
Acked-by: Yuezhang Mo <Yuezhang.Mo@...y.com>