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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <52218ac9664b406d897ca3c0bd0bef5e@BJMBX01.spreadtrum.com>
Date: Tue, 17 Jun 2025 09:53:57 +0000
From: 张政旭 (Zhengxu Zhang)
	<Zhengxu.Zhang@...soc.com>
To: "Yuezhang.Mo@...y.com" <Yuezhang.Mo@...y.com>,
        Cixi Geng
	<cixi.geng@...ux.dev>,
        "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>,
        王皓 (Hao_hao Wang) <Hao_hao.Wang@...soc.com>,
        牛志国 (Zhiguo Niu) <Zhiguo.Niu@...soc.com>
Subject: 答复: [PATCH] exfat: fdatasync flag should be same like generic_write_sync()



> -----邮件原件-----
> 发件人: Yuezhang.Mo@...y.com <Yuezhang.Mo@...y.com>
> 发送时间: 2025年6月17日 11:32
> 收件人: 张政旭 (Zhengxu Zhang) <Zhengxu.Zhang@...soc.com>; Cixi Geng
> <cixi.geng@...ux.dev>; linkinjeon@...nel.org; sj1557.seo@...sung.com
> 抄送: linux-fsdevel@...r.kernel.org; linux-kernel@...r.kernel.org; 王皓 (Hao_hao
> Wang) <Hao_hao.Wang@...soc.com>
> 主题: Re: [PATCH] exfat: fdatasync flag should be same like generic_write_sync()
> 
> 
> 
> > > > --- a/fs/exfat/file.c
> > > > +++ b/fs/exfat/file.c
> > > > @@ -625,7 +625,7 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb,
> > > > struct iov_iter *iter)
> > > >
> > > >        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);
> > > > +                               (iocb->ki_flags & IOCB_SYNC) ? 0 : 1);
> > >
> > > How about calling generic_write_sync() instead of vfs_fsync_range(), like in
> > > generic_file_write_iter()?
> > The second arg of vfs_fsync_range "pos" maybe changed by valid_size (if pos >
> valid_size).
> > It can not replace by iocb->ki_pos - ret (ret by __generic_file_write_iter).
> > So current way maybe better.
> 
> Here we synchronize the areas written by exfat_extend_valid_size() and
> __generic_file_write_iter() if valid_size < pos.
> 
> The lengths of these two write areas are 'pos-valid_size' and 'ret'.
> We can use generic_write_sync() and pass it the sum of these two lengths.
> 
> Of course, regardless of whether valid_size < pos, exfat_file_write_iter() only
> needs to return the length written by __generic_file_write_iter().

I try the sum of 'pos-valid_size' and 'ret',like this:
        if (iocb->ki_pos > pos) {
                ssize_t err = generic_write_sync(iocb, pos + ret - valid_size);
                if (err < 0)
                        return err;
        }
The test crashed, that maybe io error. 
So I try a simple way that use iocb->ki_pos - pos. like this:
        if (iocb->ki_pos > pos) {
                ssize_t err = generic_write_sync(iocb, iocb->ki_pos - pos);
                if (err < 0)
                        return err;
        }
The test pass. pls check again.