[Qemu-devel] [PATCH] qcow2: Change default for new images to compat=1.1

[Qemu-devel] [PATCH] qcow2: Change default for new images to compat=1.1

[Kevin Wolf]

By the time that qemu 1.7 will be released, enough time will has passed
since qemu 1.1, which is the first version to understand version 3
images, that changing the default shouldn't hurt many people any more
and the benefits of using the new format outweigh the pain.

qemu-iotests already runs with compat=1.1 by default.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index 3376901..42ea7ec 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1402,7 +1402,7 @@ static int qcow2_create(const char *filename, QEMUOptionParameter *options)
     int flags = 0;
     size_t cluster_size = DEFAULT_CLUSTER_SIZE;
     int prealloc = 0;
-    int version = 2;
+    int version = 3;
 
     /* Read out options */
     while (options && options->name) {
-- 
1.8.1.4

Re: [Qemu-devel] [PATCH] qcow2: Change default for new images to compat=1.1

[Stefan Hajnoczi]

On Mon, Aug 19, 2013 at 11:25:33AM +0200, Kevin Wolf wrote:
> By the time that qemu 1.7 will be released, enough time will has passed

s/has/have/

> since qemu 1.1, which is the first version to understand version 3
> images, that changing the default shouldn't hurt many people any more
> and the benefits of using the new format outweigh the pain.

In particular, compat=1.1 images include:
 * Feature bit fields which make the format more easily extensible
 * Zero clusters for data cluster preallocation, discard, efficient zero
   block migration, or block-backup
 * Lazy refcounts

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

Stefan

Re: [Qemu-devel] [PATCH] qcow2: Change default for new images to compat=1.1

[Eric Blake]

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On 08/19/2013 03:25 AM, Kevin Wolf wrote:
> By the time that qemu 1.7 will be released, enough time will has passed
> since qemu 1.1, which is the first version to understand version 3
> images, that changing the default shouldn't hurt many people any more
> and the benefits of using the new format outweigh the pain.
> 
> qemu-iotests already runs with compat=1.1 by default.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block/qcow2.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Libvirt is currently being patched to explicitly request older formats
when needed; that should land in libvirt before qmeu 1.7, so from that
point of view, I have no objection to this.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH] qcow2: Change default for new images to compat=1.1

[Ján Tomko]

On 08/19/2013 11:25 AM, Kevin Wolf wrote:
> By the time that qemu 1.7 will be released, enough time will has passed
> since qemu 1.1, which is the first version to understand version 3
> images, that changing the default shouldn't hurt many people any more
> and the benefits of using the new format outweigh the pain.
> 
> qemu-iotests already runs with compat=1.1 by default.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block/qcow2.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 3376901..42ea7ec 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -1402,7 +1402,7 @@ static int qcow2_create(const char *filename, QEMUOptionParameter *options)
>      int flags = 0;
>      size_t cluster_size = DEFAULT_CLUSTER_SIZE;
>      int prealloc = 0;
> -    int version = 2;
> +    int version = 3;
>  
>      /* Read out options */
>      while (options && options->name) {
>

This does not affect qemu-img (or bdrv_img_create), as it gets overwritten
with 2 when BLOCK_OPT_COMPAT_LEVEL is present in options, but the value is NULL.

Should this go into qcow2_create_options[] as well?

Jan

Re: [Qemu-devel] [PATCH] qcow2: Change default for new images to compat=1.1

[Kevin Wolf]

Am 23.08.2013 um 13:05 hat Ján Tomko geschrieben:
> On 08/19/2013 11:25 AM, Kevin Wolf wrote:
> > By the time that qemu 1.7 will be released, enough time will has passed
> > since qemu 1.1, which is the first version to understand version 3
> > images, that changing the default shouldn't hurt many people any more
> > and the benefits of using the new format outweigh the pain.
> > 
> > qemu-iotests already runs with compat=1.1 by default.
> > 
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> >  block/qcow2.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/block/qcow2.c b/block/qcow2.c
> > index 3376901..42ea7ec 100644
> > --- a/block/qcow2.c
> > +++ b/block/qcow2.c
> > @@ -1402,7 +1402,7 @@ static int qcow2_create(const char *filename, QEMUOptionParameter *options)
> >      int flags = 0;
> >      size_t cluster_size = DEFAULT_CLUSTER_SIZE;
> >      int prealloc = 0;
> > -    int version = 2;
> > +    int version = 3;
> >  
> >      /* Read out options */
> >      while (options && options->name) {
> >
> 
> This does not affect qemu-img (or bdrv_img_create), as it gets overwritten
> with 2 when BLOCK_OPT_COMPAT_LEVEL is present in options, but the value is NULL.

Whoops... Thanks for catching this, I'll send a v2.

> Should this go into qcow2_create_options[] as well?

Not sure what you want to change in the options array? It doesn't seem
to denote a default.

Kevin