Re: [Qemu-devel] [PATCH v6 2/2] qemu-img: Document --force-share / -U

[Kevin Wolf]

Am 30.01.2018 um 15:23 hat Eric Blake geschrieben:
> On 01/30/2018 12:34 AM, Fam Zheng wrote:
> > Signed-off-by: Fam Zheng <address@hidden>
> > Signed-off-by: Kevin Wolf <address@hidden>
> > ---
> >  qemu-img.texi | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/qemu-img.texi b/qemu-img.texi
> > index 60a0e080c6..ec7e2f5d1e 100644
> > --- a/qemu-img.texi
> > +++ b/qemu-img.texi
> > @@ -86,6 +86,13 @@ exclusive with the @var{-O} parameters. It is currently 
> > required to also use
> >  the @var{-n} parameter to skip image creation. This restriction may be 
> > relaxed
> >  in a future release.
> >  
> > address@hidden --force-share (-U)
> > +If specified, @code{qemu-img} will open the image in shared mode, allowing
> > +concurrent writers. For example, this can be used to get the image 
> > information
> 
> Actually, we only permit one writer at a time.  Would it be better to
> say "allowing a concurrent writer"?

As far as qemu-img is concerned, multiple writers to the image are
allowed. There may be further restrictions imposed by a writer so that a
second writer isn't allowed, but with raw images and share-rw=on nothing
prevents two qemu instances writing to the same image while qemu-img is
accessing it read-only.

Kevin

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