From: Richard Weinberger <richard@nod.at>
To: hujianyang <hujianyang@huawei.com>
Cc: linux-mtd@lists.infradead.org, computersforpeace@gmail.com,
dwmw2@infradead.org, linux-kernel@vger.kernel.org,
dedekind1@gmail.com
Subject: Re: [PATCH] UBI: vtbl: Use ubi_eba_atomic_leb_change()
Date: Fri, 31 Oct 2014 11:57:38 +0100 [thread overview]
Message-ID: <54536B22.4000807@nod.at> (raw)
In-Reply-To: <54536834.1020005@huawei.com>
Am 31.10.2014 um 11:45 schrieb hujianyang:
> This question is basing on your comment for this patch:
>
> """
> we can guarantee that the first VTBL record is always
> correct and we don't really need the second one anymore.
> """
>
> I think that means one PEB is enough in your considering.
> So I want to know if you are sure about this. Because
> we use two leb for master_node in ubifs-level. So maybe
> VTBL is like super_node, not master_node, right?
Yes, technically one PEB is enough if atomic leb change is used.
But existing UBI implementations want a second one
and a backup VTBL PEB is good for robustness.
i.e. if the PEB turns bad we have a backup and do not lose
all volume meta information.
Thanks,
//richard
WARNING: multiple messages have this Message-ID (diff)
From: Richard Weinberger <richard@nod.at>
To: hujianyang <hujianyang@huawei.com>
Cc: dedekind1@gmail.com, dwmw2@infradead.org,
computersforpeace@gmail.com, linux-mtd@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] UBI: vtbl: Use ubi_eba_atomic_leb_change()
Date: Fri, 31 Oct 2014 11:57:38 +0100 [thread overview]
Message-ID: <54536B22.4000807@nod.at> (raw)
In-Reply-To: <54536834.1020005@huawei.com>
Am 31.10.2014 um 11:45 schrieb hujianyang:
> This question is basing on your comment for this patch:
>
> """
> we can guarantee that the first VTBL record is always
> correct and we don't really need the second one anymore.
> """
>
> I think that means one PEB is enough in your considering.
> So I want to know if you are sure about this. Because
> we use two leb for master_node in ubifs-level. So maybe
> VTBL is like super_node, not master_node, right?
Yes, technically one PEB is enough if atomic leb change is used.
But existing UBI implementations want a second one
and a backup VTBL PEB is good for robustness.
i.e. if the PEB turns bad we have a backup and do not lose
all volume meta information.
Thanks,
//richard
next prev parent reply other threads:[~2014-10-31 10:58 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-25 17:43 [PATCH] UBI: vtbl: Use ubi_eba_atomic_leb_change() Richard Weinberger
2014-10-25 17:43 ` Richard Weinberger
2014-10-30 8:55 ` Artem Bityutskiy
2014-10-30 8:55 ` Artem Bityutskiy
2014-10-31 4:03 ` hujianyang
2014-10-31 4:03 ` hujianyang
2014-10-31 8:09 ` Richard Weinberger
2014-10-31 8:09 ` Richard Weinberger
2014-10-31 10:45 ` hujianyang
2014-10-31 10:45 ` hujianyang
2014-10-31 10:57 ` Richard Weinberger [this message]
2014-10-31 10:57 ` Richard Weinberger
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