All of lore.kernel.org
 help / color / mirror / Atom feed
From: Melvin Vermeeren <vermeeren@vermwa.re>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Mike Snitzer <msnitzer@redhat.com>,
	dm-devel@redhat.com, Milan Broz <mbroz@redhat.com>
Subject: Re: [dm-devel] [PATCH v2] dm-integrity: if we have discard support, use it when recalculating
Date: Wed, 05 May 2021 21:27:41 +0200	[thread overview]
Message-ID: <2912930.OmXdaqUpTP@verm-r4e> (raw)
In-Reply-To: <alpine.LRH.2.02.2105051444010.31064@file01.intranet.prod.int.rdu2.redhat.com>


[-- Attachment #1.1: Type: text/plain, Size: 954 bytes --]

Hi,

On Wednesday, 5 May 2021 20:48:47 CEST Mikulas Patocka wrote:
> It doesn't matter if the device is discarded or not. If the metadata
> constains the discard filler, dm-integrity won't check the checksum - so
> the data can contain anything.
> 
> ...
>
> The device after discard may contain random pattern (some SSDs really do)
> - so when the metadata contains the discard filler, the data may contain
> anything.

So if an existing SSD is formatted with --no-wipe --data-device option and 
then opened with --integrity-recalculate all metadata will contain the discard 
filler with this patch.

So then, all the current data in the drive is not checked for integrity 
because it contains discard filler. This means that integrity recalculation 
itself never takes place for existing data. Meaning that only newly written 
data to SSD device will actually have integrity protection.

Is this correct?

Cheers,

-- 
Melvin Vermeeren
Systems engineer

[-- Attachment #1.2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

[-- Attachment #2: Type: text/plain, Size: 97 bytes --]

--
dm-devel mailing list
dm-devel@redhat.com
https://listman.redhat.com/mailman/listinfo/dm-devel

  reply	other threads:[~2021-05-06  7:57 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-28 21:00 [dm-devel] [PATCH v2] dm-integrity: if we have discard support, use it when recalculating Mikulas Patocka
2021-04-30 19:39 ` Melvin Vermeeren
2021-05-05 18:48   ` Mikulas Patocka
2021-05-05 19:27     ` Melvin Vermeeren [this message]
2021-05-05 20:05       ` Mikulas Patocka
2021-05-05 20:16         ` Melvin Vermeeren
2021-05-05 20:45           ` Mikulas Patocka
2021-05-05 21:47             ` Melvin Vermeeren
2021-05-11 17:06               ` Milan Broz
2021-05-11 18:33                 ` Melvin Vermeeren

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=2912930.OmXdaqUpTP@verm-r4e \
    --to=vermeeren@vermwa.re \
    --cc=dm-devel@redhat.com \
    --cc=mbroz@redhat.com \
    --cc=mpatocka@redhat.com \
    --cc=msnitzer@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.