From: Gao Xiang <hsiangkao@aol.com>
To: Richard Weinberger <richard.weinberger@gmail.com>
Cc: Richard Weinberger <richard@nod.at>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-erofs@lists.ozlabs.org,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: erofs: Question on unused fields in on-disk structs
Date: Thu, 22 Aug 2019 06:03:03 +0800 [thread overview]
Message-ID: <20190821220251.GA3954@hsiangkao-HP-ZHAN-66-Pro-G1> (raw)
In-Reply-To: <CAFLxGvxr2UMeVa29M9pjLtWMFPz7w6udRV38CRxEF1moyA9_Rw@mail.gmail.com>
Hi Richard,
On Wed, Aug 21, 2019 at 11:37:30PM +0200, Richard Weinberger wrote:
> Gao Xiang,
>
> On Mon, Aug 19, 2019 at 10:45 PM Gao Xiang via Linux-erofs
> <linux-erofs@lists.ozlabs.org> wrote:
> > > struct erofs_super_block has "checksum" and "features" fields,
> > > but they are not used in the source.
> > > What is the plan for these?
> >
> > Yes, both will be used laterly (features is used for compatible
> > features, we already have some incompatible features in 5.3).
>
> Good. :-)
> I suggest to check the fields being 0 right now.
> Otherwise you are in danger that they get burned if an mkfs.erofs does not
> initialize the fields.
Sorry... I cannot get the point...
super block chksum could be a compatible feature right? which means
new kernel can support it (maybe we can add a warning if such image
doesn't have a chksum then when mounting) but old kernel doesn't
care it.
Or maybe you mean these reserved fields? I have no idea all other
filesystems check these fields to 0 or not... But I think it should
be used with some other flag is set rather than directly use, right?
Thanks,
Gao Xiang
>
> --
> Thanks,
> //richard
next prev parent reply other threads:[~2019-08-21 22:03 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-19 17:10 erofs: Question on unused fields in on-disk structs Richard Weinberger
2019-08-19 20:45 ` Gao Xiang
2019-08-21 21:37 ` Richard Weinberger
2019-08-21 22:03 ` Gao Xiang [this message]
2019-08-22 8:33 ` Richard Weinberger
2019-08-22 9:05 ` Gao Xiang
2019-08-22 9:08 ` Gao Xiang
2019-08-22 14:21 ` Theodore Y. Ts'o
2019-08-22 14:29 ` Richard Weinberger
2019-08-22 14:38 ` Gao Xiang
2019-08-22 14:34 ` Gao Xiang
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