linux-kernel - Re: [PATCH alternative 2] block: fix the REQ_OP_SECURE

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Date:   Fri, 18 Mar 2022 10:11:52 +0100
From:   Christoph Hellwig <hch@....de>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Christoph Hellwig <hch@....de>, axboe@...nel.dk,
        jaegeuk@...nel.org, chao@...nel.org,
        Adrian Hunter <adrian.hunter@...el.com>,
        Daeho Jeong <daehojeong@...gle.com>,
        Eric Biggers <ebiggers@...gle.com>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mmc@...r.kernel.org
Subject: Re: [PATCH alternative 2] block: fix the REQ_OP_SECURE_ERASE
 handling to not leak erased data

On Thu, Mar 17, 2022 at 10:44:01AM +0100, Ulf Hansson wrote:
> Stating that it can't work is probably not a correct statement.
> Certainly it can, but it depends on how "secure" (or clever) the
> implementation of the FTL is in the flash media. I mean, nothing
> prevents the FTL from doing a real erase on erase block level and
> simply let the "secure erase" request wait on that operation to be
> completed.

Well, that assumes it can find all the previous copied of the data.
Having worked with various higher end SSDs FTLs I know they can't,
so if an eMMC device could that would very much surpise me given
the overhead.