All of lore.kernel.org
 help / color / mirror / Atom feed
From: Jasper Surmont <surmontjasper@gmail.com>
To: dm-devel@redhat.com
Subject: [dm-devel] [Question] Changes to dm do not reflect in underlying block device
Date: Fri, 20 May 2022 12:08:34 +0300	[thread overview]
Message-ID: <CAH4tiUu0P2FSQaN9Rk+-BC=wPntC=bBZxxj-b=3i3R6gzU8i5g@mail.gmail.com> (raw)

I created my own dm which performs some checks on writing / reading
before it remaps the request to an underlying block dev. After I set
it up and write changes (eg using 'dd') to /dev/mapper/<name>, I see
it happened correctly (eg using 'hd' on /dev/mapper/<name>). However,
the underlying block device did not change at all (again using 'hd' on
/dev/sdb1 for example).
1. How is it possible that, even though the changes are not yet
persisted to /dev/sdb1, the dm has the correct data?
2. Is this normal behavior? If not, what can I do or what am I doing
wrong to fix this?

Thanks!

Cheers, Jasper

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


                 reply	other threads:[~2022-05-25  7:23 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

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='CAH4tiUu0P2FSQaN9Rk+-BC=wPntC=bBZxxj-b=3i3R6gzU8i5g@mail.gmail.com' \
    --to=surmontjasper@gmail.com \
    --cc=dm-devel@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.