[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PULL 06/18] qemu-img: Add --target-is-zero to convert

From: Eric Blake
Subject: Re: [PULL 06/18] qemu-img: Add --target-is-zero to convert
Date: Thu, 20 Feb 2020 10:36:04 -0600
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1

On 2/20/20 10:06 AM, Max Reitz wrote:
From: David Edmondson <address@hidden>

In many cases the target of a convert operation is a newly provisioned
target that the user knows is blank (reads as zero). In this situation
there is no requirement for qemu-img to wastefully zero out the entire

Add a new option, --target-is-zero, allowing the user to indicate that
an existing target device will return zeros for all reads.

Signed-off-by: David Edmondson <address@hidden>
Message-Id: <address@hidden>
Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Signed-off-by: Max Reitz <address@hidden>
  docs/interop/qemu-img.rst |  9 ++++++++-
  qemu-img-cmds.hx          |  4 ++--
  qemu-img.c                | 26 +++++++++++++++++++++++---
  3 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/docs/interop/qemu-img.rst b/docs/interop/qemu-img.rst
index 42e4451db4..5f40137c10 100644
--- a/docs/interop/qemu-img.rst
+++ b/docs/interop/qemu-img.rst
@@ -214,6 +214,13 @@ Parameters to convert subcommand:
    will still be printed.  Areas that cannot be read from the source will be
    treated as containing only zeroes.
+.. option:: --target-is-zero
+  Assume that reading the destination image will always return
+  zeros. This parameter is mutually exclusive with a destination image

Late tweak now that this is in a pull request, so we may want a followup patch, but:

The image doesn't always return zeros after we write to it, maybe we should tweak this sentence:

Assume that reading the destination image will initially return all zeros.

Also, my earlier comment about 'zeroes' one line before 'zeros' still applies - although both spellings are valid, we look inconsistent when we can't make up our mind within two adjacent paragraphs.

Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

reply via email to

[Prev in Thread] Current Thread [Next in Thread]