Message-ID: <5485A0E8.4050901@codeaurora.org>
Date: Mon, 08 Dec 2014 15:00:24 +0200
From: Tanya Brokhman <tlinder@codeaurora.org>
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To: Richard Weinberger <richard@nod.at>, dedekind1@gmail.com
CC: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/6] UBI: Fastmap: Notify user in case of an ubi_update_fastmap()
 failure
References: <1417347340-6872-1-git-send-email-richard@nod.at> <1417347340-6872-4-git-send-email-richard@nod.at> <54845D53.1070903@codeaurora.org> <548462A8.2010107@nod.at> <54854C28.4050107@codeaurora.org> <54856B54.7020306@nod.at>
In-Reply-To: <54856B54.7020306@nod.at>
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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@nod.at>
>>>>> ---
>>>>>     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
-- 
Qualcomm Israel, on behalf of Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
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