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Re: [PATCHv3] a new filesystem module for nilfs2
From: |
Jiro SEKIBA |
Subject: |
Re: [PATCHv3] a new filesystem module for nilfs2 |
Date: |
Mon, 26 Apr 2010 10:42:08 +0900 |
User-agent: |
Wanderlust/2.14.0 (Africa) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (Gojō) APEL/10.7 Emacs/22.3 (i486-pc-linux-gnu) MULE/5.0 (SAKAKI) |
Hi,
At Sat, 24 Apr 2010 22:12:52 +0200,
Vladimir 'φ-coder/phcoder' Serbinenko wrote:
>
> Committed. One question:
Thank you!
> + .reserved_first_sector = 1,
>
> This line claims that overwriting first sector of nilfs won't destroy any
> data or metadata. Is it so?
>
Oh, that is the one I copied from fs/ext2.c without any doubt.
But I think it's ok, since nilfs2 super block resides at 1K from
begining of the parition. So any data within 1K will ignored.
I believe sector is assumed 512bytes, so first sector would be within 1K
which is not used in nilfs2.
I checked with loop back device and write random data in first 1K,
partion is healthy and mountable. And the range 0-1K is unchanged.
thanks
regards,
> Jiro SEKIBA wrote:
> > Hi,
> >
> > Thank you very much for the comments!
> > I revised the patch to reflect the comments.
> >
> >
> >> + {
> >> + grub_error(GRUB_ERR_BAD_FS,"btree corruption\n");
> >> + return -1;
> >> + }
> >> What do you think about possible fallback to iterate over all nodes in
> >> case of fs corruption?
> >>
> >
> > The case that btree is corrupted, it's very hard to take any action to
> > recover
> > because it is not possible to distinguish which block has meta data
> > or which block has data without btree information.
> >
> > nilfs2 has ability to mount old checkpoint by specifying checkpoint number.
> > So using old checkpoint is one of the possible fallback if all the blocks
> > belonging to the old checkpoint is healthy. But it requires some more work.
> >
> > thanks,
> >
> > regards
> >
> > ------------------------------------------------------------------------
> >
> >
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > Grub-devel mailing list
> > address@hidden
> > http://lists.gnu.org/mailman/listinfo/grub-devel
>
>
> --
> Regards
> Vladimir 'φ-coder/phcoder' Serbinenko
>
>
--
Jiro SEKIBA <address@hidden>