Re: [PATCH] ubifs: Add freeze support

From	Richard Weinberger <richard@nod.at>
Newsgroups	linux.kernel
Subject	Re: [PATCH] ubifs: Add freeze support
Date	2017-05-29 11:10 +0200
Message-ID	<tMoQy-66X-17@gated-at.bofh.it> (permalink)
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Amir, Hyunchul,

Am 29.05.2017 um 07:40 schrieb Amir Goldstein:
> On Mon, May 29, 2017 at 7:40 AM, Hyunchul Lee <hyc.lee@gmail.com> wrote:
>>
>> and I missed the following case.
>>
>> in some embedded systems, clean-up for shutdown should be fast.
>> during this clean-up, freeze file system to guarantee integrity.
>> umount with MNT_DETACH is not suitable because of not killing tasks.

more details please, UBIFS is designed to survive a power-cut/reboot/etc.
at any time. How would it corrupt?

> Interesting point. It seems that good old "sync; reboot" does not cut
> it anymore.
> Not even emergency remount read-only sysrq trigger.
> 
> Some of you may have been following this thread on fsdevel:
> https://www.spinics.net/lists/linux-xfs/msg06953.html
> 
> Probably less have been following this longer thread on xfs list:
> https://www.spinics.net/lists/linux-xfs/msg06883.html

Well, UBIFS is a bit different.
The UBIFS journal is not an add-on feature, you have to replay it in
any case. Otherwise you're facing corrupted data.
What simple bootloaders often do is it replaying the journal only to memory
but don't write back to the MTD.

Thanks,
//richard

Thread

[PATCH] ubifs: Add freeze support Hyunchul Lee <hyc.lee@gmail.com> - 2017-05-26 01:40 +0200
  Re: [PATCH] ubifs: Add freeze support Richard Weinberger <richard@nod.at> - 2017-05-26 12:00 +0200
    Re: [PATCH] ubifs: Add freeze support Christoph Hellwig <hch@infradead.org> - 2017-05-27 10:20 +0200
    Re: [PATCH] ubifs: Add freeze support Hyunchul Lee <hyc.lee@gmail.com> - 2017-05-29 03:20 +0200
      Re: [PATCH] ubifs: Add freeze support Hyunchul Lee <hyc.lee@gmail.com> - 2017-05-29 06:50 +0200
        Re: [PATCH] ubifs: Add freeze support Amir Goldstein <amir73il@gmail.com> - 2017-05-29 07:50 +0200
          Re: [PATCH] ubifs: Add freeze support Richard Weinberger <richard@nod.at> - 2017-05-29 11:10 +0200
            Re: [PATCH] ubifs: Add freeze support Amir Goldstein <amir73il@gmail.com> - 2017-05-29 12:10 +0200
              Re: [PATCH] ubifs: Add freeze support Richard Weinberger <richard@nod.at> - 2017-05-29 12:20 +0200
                Re: [PATCH] ubifs: Add freeze support Amir Goldstein <amir73il@gmail.com> - 2017-05-29 13:50 +0200
  Re: [PATCH] ubifs: Add freeze support Christoph Hellwig <hch@infradead.org> - 2017-05-27 10:30 +0200
    Re: [PATCH] ubifs: Add freeze support Hyunchul Lee <hyc.lee@gmail.com> - 2017-05-29 02:50 +0200
      Re: [PATCH] ubifs: Add freeze support Hyunchul Lee <hyc.lee@gmail.com> - 2017-05-29 04:30 +0200
        Re: [PATCH] ubifs: Add freeze support Richard Weinberger <richard@nod.at> - 2017-05-29 10:50 +0200
          Re: [PATCH] ubifs: Add freeze support Hyunchul Lee <hyc.lee@gmail.com> - 2017-05-30 04:40 +0200
            Re: [PATCH] ubifs: Add freeze support Richard Weinberger <richard@nod.at> - 2017-05-30 10:00 +0200

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