Am 30.09.2015 um 18:06 hat Paolo Bonzini geschrieben:
>
>
> On 30/09/2015 18:02, Jeff Cody wrote:
> > As a general rule for blockjobs, I disagree.
> >
> > Right away, there is a key difference: we don't know that the image is
> > (or should be) empty.
>
> Not necessarily empty. sync='top' && m
On 30/09/2015 16:43, Jeff Cody wrote:
> One issue is that QEMU will do mode!='existing' && sync!='full' for
> drivers that do not support backing files (raw host devices, for
> instance).
Yup, this can be used to get a mirror of future operations (the idea was
to support things such as antivirus
On 30/09/2015 18:02, Jeff Cody wrote:
> As a general rule for blockjobs, I disagree.
>
> Right away, there is a key difference: we don't know that the image is
> (or should be) empty.
Not necessarily empty. sync='top' && mode='existing' &&
!target->backing_file, for example, makes sense if the
On Tue, Sep 29, 2015 at 12:52:33PM +0200, Paolo Bonzini wrote:
>
>
> On 29/09/2015 11:35, Kevin Wolf wrote:
> > The caller could be copying the backing file in the background and it
> > may not yet be finished.
>
> Yes, and this is permitted (the destination file of mirroring is opened
> with BD
On Wed, Sep 30, 2015 at 05:26:28PM +0200, Kevin Wolf wrote:
> Am 30.09.2015 um 16:43 hat Jeff Cody geschrieben:
> > On Tue, Sep 29, 2015 at 12:52:33PM +0200, Paolo Bonzini wrote:
> > >
> > >
> > > On 29/09/2015 11:35, Kevin Wolf wrote:
> > > > The caller could be copying the backing file in the b
Am 30.09.2015 um 16:43 hat Jeff Cody geschrieben:
> On Tue, Sep 29, 2015 at 12:52:33PM +0200, Paolo Bonzini wrote:
> >
> >
> > On 29/09/2015 11:35, Kevin Wolf wrote:
> > > The caller could be copying the backing file in the background and it
> > > may not yet be finished.
> >
> > Yes, and this i
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On 29/09/2015 10:39, Kevin Wolf wrote:
> bdrv_has_zero_init() takes care of that, in theory. The "problem"
> here is that the target is opened with BDRV_O_NO_BACKING, so the
> block layer doesn't consider this an image with a backing file.
I think
On 29/09/2015 11:35, Kevin Wolf wrote:
> The caller could be copying the backing file in the background and it
> may not yet be finished.
Yes, and this is permitted (the destination file of mirroring is opened
with BDRV_O_NO_BACKING).
Some more assumptions arise when block-job-complete is invok
Am 29.09.2015 um 10:42 hat Paolo Bonzini geschrieben:
>
>
> On 29/09/2015 10:10, Kevin Wolf wrote:
> >> When mode == 'existing' for a shallow mirror (sync != 'full'),
> >> that is the caller stating that the guest-visible contents of the
> >> destination match the guest-visible contents of the ba
On 29/09/2015 10:10, Kevin Wolf wrote:
>> When mode == 'existing' for a shallow mirror (sync != 'full'),
>> that is the caller stating that the guest-visible contents of the
>> destination match the guest-visible contents of the backing
>> image. The only sectors to be copied are those that diff
Am 28.09.2015 um 23:57 hat Jeff Cody geschrieben:
> On Sep 28, 2015 5:31 PM, "Kevin Wolf" wrote:
> >
>
> (Responding from mobile phone again)
>
> > Am 28.09.2015 um 05:29 hat Jeff Cody geschrieben:
> > > During mirror, if the target device does not have support zero
> > > initialization, a mirro
Am 28.09.2015 um 22:31 hat Eric Blake geschrieben:
> On 09/28/2015 08:13 AM, Paolo Bonzini wrote:
> >
> >
> > On 28/09/2015 05:29, Jeff Cody wrote:
> >> This only occurs under two conditions:
> >>
> >> 1. 'mode' != "existing"
> >> 2. bdrv_has_zero_init(target) == NULL
> >>
> >
> > I'm no
On 09/28/2015 03:32 PM, Jeff Cody wrote:
> I guess that makes sense. What about the case when the target is a raw
> device without zero init? There is no backing file... Of course, perhaps
> in the raw case the user should be using sync==full anyways.
>
>>
>> 2) even with mode == "existing" yo
On Sep 28, 2015 5:34 PM, "Kevin Wolf" wrote:
>
> Am 28.09.2015 um 05:29 hat Jeff Cody geschrieben:
> > During mirror, if the target device does not have support zero
> > initialization, a mirror may result in a corrupt image.
> >
> > For instance, on mirror to a host device with format = raw, what
On Sep 28, 2015 5:31 PM, "Kevin Wolf" wrote:
>
(Responding from mobile phone again)
> Am 28.09.2015 um 05:29 hat Jeff Cody geschrieben:
> > During mirror, if the target device does not have support zero
> > initialization, a mirror may result in a corrupt image.
>
> I think you want to check thi
On 09/28/2015 08:13 AM, Paolo Bonzini wrote:
>
>
> On 28/09/2015 05:29, Jeff Cody wrote:
>> This only occurs under two conditions:
>>
>> 1. 'mode' != "existing"
>> 2. bdrv_has_zero_init(target) == NULL
>>
>
> I'm not sure if mode != "existing" actually matters. I think what
> actually m
On Sep 28, 2015 4:12 PM, "Paolo Bonzini" wrote:
>
>
Replying from mobile; please excuse any formatting issues.
>
> On 28/09/2015 05:29, Jeff Cody wrote:
> > This only occurs under two conditions:
> >
> > 1. 'mode' != "existing"
> > 2. bdrv_has_zero_init(target) == NULL
> >
>
> I'm not su
Am 28.09.2015 um 05:29 hat Jeff Cody geschrieben:
> During mirror, if the target device does not have support zero
> initialization, a mirror may result in a corrupt image.
I think you want to check this sentence. ("During mirror [...], a
mirror may result [...]")
> For instance, on mirror to a h
Am 28.09.2015 um 05:29 hat Jeff Cody geschrieben:
> During mirror, if the target device does not have support zero
> initialization, a mirror may result in a corrupt image.
>
> For instance, on mirror to a host device with format = raw, whatever
> random data is on the target device will still be
On 28/09/2015 05:29, Jeff Cody wrote:
> This only occurs under two conditions:
>
> 1. 'mode' != "existing"
> 2. bdrv_has_zero_init(target) == NULL
>
I'm not sure if mode != "existing" actually matters. I think what
actually matters is sync == "full".
The reasons are:
1) with sync !=
During mirror, if the target device does not have support zero
initialization, a mirror may result in a corrupt image.
For instance, on mirror to a host device with format = raw, whatever
random data is on the target device will still be there for unallocated
sectors.
This is because during the m
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