Re: f2fs_bug_on in init_dirty_segmap

[Philippe De Muyter <phdm@macq.eu>]

Hi,

thanks for your quick answer

On Wed, Mar 08, 2017 at 01:52:03PM -0800, Jaegeuk Kim wrote:
> Hi,
> 
> On 03/08, Philippe De Muyter wrote:
> > Hi f2fs developpers,
> > 
> > Please excuse my maybe dumb question.
> > 
> > I recently encountered a kernel panic at root mount time (thus making my
> > system unusable, as my root partition is formatted as f2fs) due to the
> > following segment in fs/f2fs/segment.c:init_dirty_segmap
> > 
> > 		if (valid_blocks > sbi->blocks_per_seg) {
> >                         f2fs_bug_on(sbi, 1); <<<<<<<<<<<<<<<<<<<<
> > 			continue;
> > 		}
> > 
> > Is that really a condition requiring a kernel panic, or could a read-only
> > mount be allowed ?
> 
> It would be helpful that you can remain your kernel and f2fs-tools version
> information, as well as fsck.f2fs result.

It is actually a Freescale (now NXP) provided kernel tagged rel_imx_4.1.15_1.2.0_ga
available at git://git.freescale.com/imx/linux-2.6-imx.git 

I surmise that the f2fs driver is the one from the linux-4.1 version.

> 
> You can get the latest f2fs-tools from
> http://git.kernel.org/cgit/linux/kernel/git/jaegeuk/f2fs-tools.git/log/?h=dev-test
> 
> Anyway, if you don't have time, you may have some options like:
> 
> 1. disable F2FS_CHECK_FS in Kconfig
>  : bypass BUG_ON here, so mount-ro would be preferable.

Actually F2FS_CHECK_FS was disabled, but kernel panic'ed.

> 
> 2. run fsck.f2fs
>  : fix some inconsistency and let you mount your system again.
> 
> So, I think you'd better try #1 to retrieve your important data, and then
> #2 to fix something wrong.

There wasn't a need to retrieve important data, as it is an unattended device
in the wild.  The problem was that boot did not succeed anymore and the device
needed a return to our aftersales department for reflashing.  Without the 'panic',
and with a read-only mount we could probably fix it without reflashing
and without return.

If that happens again, I'll try to provide more information.
> 
> > 
> > Philippe

-- 
Philippe De Muyter +32 2 6101532 Macq SA rue de l'Aeronef 2 B-1140 Bruxelles

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