qemu-devel.nongnu.org archive mirror
 help / color / mirror / Atom feed
From: John Snow <jsnow@redhat.com>
To: Max Reitz <mreitz@redhat.com>, qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
	Markus Armbruster <armbru@redhat.com>,
	qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v2 0/2] blockdev: Overlays are not snapshots
Date: Mon, 3 Jun 2019 18:09:22 -0400	[thread overview]
Message-ID: <e128b50e-88fb-b2bb-e773-b9c02db0cd28@redhat.com> (raw)
In-Reply-To: <20190603202236.1342-1-mreitz@redhat.com>



On 6/3/19 4:22 PM, Max Reitz wrote:
> QEMU’s always been confused over what a snapshot is: Is it the overlay?
> Is it the backing image?
> 
> Confusion is rarely a good thing.  I can’t think of any objective reason
> why the overlay would be a snapshot.  A snapshot is something that does
> not change over time; the overlay does.
> 
> (I suppose historically the reason is that “Taking an overlay” makes no
> sense, so the operations are called “Taking a snapshot”.  Somehow, this
> meaning carried over to the new file that is created during that
> operation; if “Creating a snapshot” creates a file, that file must be
> the snapshot, right?  Well, no, it isn’t.)
> 
> Let’s fix this as best as we can.  Better Nate than lever.
> 
> 
> v2:
> - Don’t break the iotests for a change
>   (kept Eric’s R-b, because it felt like the right thing to do)
> 
> 
> git backport-diff against v1:
> 
> Key:
> [----] : patches are identical
> [####] : number of functional differences between upstream/downstream patch
> [down] : patch is downstream-only
> The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively
> 
> 001/2:[----] [--] 'qapi/block-core: Overlays are not snapshots'
> 002/2:[0010] [FC] 'blockdev: Overlays are not snapshots'
> 
> 
> Max Reitz (2):
>   qapi/block-core: Overlays are not snapshots
>   blockdev: Overlays are not snapshots
> 
>  qapi/block-core.json       | 20 ++++++++++----------
>  blockdev.c                 | 10 +++++-----
>  tests/qemu-iotests/085.out | 10 +++++-----
>  3 files changed, 20 insertions(+), 20 deletions(-)
> 

Makes good sense to me.

There are only 3,283 things named "snapshot" in QEMU so one less is
probably not the worst.

Reviewed-by: John Snow <jsnow@redhat.com>


  parent reply	other threads:[~2019-06-03 22:11 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-03 20:22 [Qemu-devel] [PATCH v2 0/2] blockdev: Overlays are not snapshots Max Reitz
2019-06-03 20:22 ` [Qemu-devel] [PATCH v2 1/2] qapi/block-core: " Max Reitz
2019-06-05  5:43   ` Markus Armbruster
2019-06-03 20:22 ` [Qemu-devel] [PATCH v2 2/2] blockdev: " Max Reitz
2019-06-03 22:09 ` John Snow [this message]
2019-06-04  8:40 ` [Qemu-devel] [Qemu-block] [PATCH v2 0/2] " Alberto Garcia
2019-06-13 19:41 ` [Qemu-devel] " Max Reitz

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=e128b50e-88fb-b2bb-e773-b9c02db0cd28@redhat.com \
    --to=jsnow@redhat.com \
    --cc=armbru@redhat.com \
    --cc=kwolf@redhat.com \
    --cc=mreitz@redhat.com \
    --cc=qemu-block@nongnu.org \
    --cc=qemu-devel@nongnu.org \
    /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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).