On Thu, Mar 09, 2017 at 03:11:46PM -0800, Jaegeuk Kim wrote:
> On 03/09, Philippe De Muyter wrote:
> > 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.
>
> So, you got a warning message from there?
>
> #ifdef CONFIG_F2FS_CHECK_FS
> #define f2fs_bug_on(sbi, condition) BUG_ON(condition)
> #define f2fs_down_write(x, y) down_write_nest_lock(x, y)
> #else
> #define f2fs_bug_on(sbi, condition) \
> do { \
> if (unlikely(condition)) { \
> WARN_ON(1); \
> set_sbi_flag(sbi, SBI_NEED_FSCK); \
> } \
> } while (0)
> #define f2fs_down_write(x, y) down_write(x)
> #endif
Yes, I got a 'panic'. I'll look deeper into that and let you know.
>
> > >
> > > 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.
>
> So, there is no fscking before mounting any filesystem during boot-up, right?
> Most of distros and android do that and provide a recovery mode tho.
No, there is no fsck before mounting the root filesystem during boot-up.
But I do my best to avoid writing in the root partition. It's not read-only,
but all log, lock, run, cache and tmp files are in tmpfs partitions. I have
just noticed though that the partition is mounted with 'relatime', not 'noatime'
as I would like, but I do not know where this 'relatime' option comes from.
Is 'relatime' a default mount option for f2fs ?
>
> I think there is a way to mount with ro without loading in-memory structures
> which results in potential panics. Will cosider about that. ;)
>
> Note, there is a backported f2fs for v4.1 which I've been maintaining.
>
> http://git.kernel.org/cgit/linux/kernel/git/jaegeuk/f2fs-stable.git/log/?h=linux-4.1.y
Thank you. I will apply it
Philippe
--
Philippe De Muyter +32 2 6101532 Macq SA rue de l'Aeronef 2 B-1140 Bruxelles
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