Re: [PATCH 3/6] UBI: Fastmap: Notify user in case of an ubi_update_fastmap() failure

[Tanya Brokhman]

On 12/8/2014 11:11 AM, Richard Weinberger wrote:
> Hi!
>
> Am 08.12.2014 um 07:58 schrieb Tanya Brokhman:
> > On 12/7/2014 4:22 PM, Richard Weinberger wrote:
> > > Am 07.12.2014 um 14:59 schrieb Tanya Brokhman:
> > > > Hi Richard,
> > > >
> > > > On 11/30/2014 1:35 PM, Richard Weinberger wrote:
> > > > > If ubi_update_fastmap() fails notify the user.
> > > > > This is not a hard error as ubi_update_fastmap() makes sure that upon failure
> > > > > the current on-flash fastmap will no be used upon next UBI attach.
> > > > >
> > > > > Signed-off-by: Richard Weinberger <richard@xxxxxx>
> > > > > ---
> > > > >     drivers/mtd/ubi/wl.c | 6 +++++-
> > > > >     1 file changed, 5 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
> > > > > index 523d8a4..7821342 100644
> > > > > --- a/drivers/mtd/ubi/wl.c
> > > > > +++ b/drivers/mtd/ubi/wl.c
> > > > > @@ -657,7 +657,11 @@ again:
> > > > >          * refill the WL pool synchronous. */
> > > > >         if (pool->used == pool->size || wl_pool->used == wl_pool->size) {
> > > > >             spin_unlock(&ubi->wl_lock);
> > > > > -        ubi_update_fastmap(ubi);
> > > > > +        ret = ubi_update_fastmap(ubi);
> > > > > +        if (ret) {
> > > > > +            ubi_msg(ubi, "Unable to write a new fastmap: %i", ret);
> > > > > +            return -ENOSPC;
> > > >
> > > > Why do you fail the whole function (ubi_wl_get_peb) if fastmap update failed? Its possible that the fm_pools were refilled correctly, and the actual fastmap_write failed, so there
> > > > is nothing preventing the user to get peb allocated and continue working. You invalidate the fastmap, so if powercut occurs a full scan will be performed. So its possible to
> > > > allocate from fm_pools (although fastmap is not valid on disc) and try writing fastmap again when the pools filled up.
> > > > I'm for the ubi_msg but against "return -ENOSPC;"
> > >
> > > Maybe the case you've described is powercut safe, but there can be other unsafe cases.
> > > Let's stay on the safe side and be paranoid, it does not hurt.
> > > If fastmap has proven stable we can start with tricky optimizations.
> >
> > I'm sorry that I'm being petty here but the commit msg states that you "notify the user in case of update fastamap failure". It says nothing about you failing ubi_wl_get_peb as
> > well. And this is a major change. At least divide this into 2 patches (so I can disagree to the function failing and agree to the msg to user :) )
>
> With user I meant users of that function.

I still don't like it.
Leaving this one for Artem... sorry

> Thanks,
> //richard
>
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/


Thanks,
Tanya Brokhman
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