Re: [PATCH 4.4 15/47] ubi: fastmap: Correctly handle interrupted erasures in EBA

[Ben Hutchings]

On Tue, 2018-07-10 at 20:24 +0200, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.ÂÂIf anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Richard Weinberger <richard@xxxxxx>
> 
> commit 781932375ffc6411713ee0926ccae8596ed0261c upstream.
> 
> Fastmap cannot track the LEB unmap operation, therefore it can
> happen that after an interrupted erasure the mapping still looks
> good from Fastmap's point of view, while reading from the PEB will
> cause an ECC error and confuses the upper layer.
> 
> Instead of teaching users of UBI how to deal with that, we read back
> the VID header and check for errors. If the PEB is empty or shows ECC
> errors we fixup the mapping and schedule the PEB for erasure.
[...]

Isn't there a risk here, that a read error leads to erasing data that
might be recoverable if the read is retried?

Ben.

-- 
Ben Hutchings, Software Developer                Â        Codethink Ltd
https://www.codethink.co.uk/                 Dale House, 35 Dale Street
                                     Manchester, M1 2HF, United Kingdom