| Message ID | 20171208014456.16635-1-famz@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Dec 08, 2017 at 09:44:56AM +0800, Fam Zheng wrote: > +@item --force-share (-U) > + > +If specified, @code{qemu-img} will open the image with shared permissions, > +which makes it less likely to conflict with a running guest's permissions due > +to image locking. For example, this can be used to get the image information > +(with 'info' subcommand) when the image is used by a running guest. Note that > +this could produce inconsistent result because of concurrent metadata changes, > +etc. The documentation isn't clear on whether read-write is supported or just read-only. Also, should it be declared a legacy option right away to discourage use in new software?
Am 08.12.2017 um 10:54 hat Stefan Hajnoczi geschrieben: > On Fri, Dec 08, 2017 at 09:44:56AM +0800, Fam Zheng wrote: > > +@item --force-share (-U) > > + > > +If specified, @code{qemu-img} will open the image with shared permissions, > > +which makes it less likely to conflict with a running guest's permissions due > > +to image locking. For example, this can be used to get the image information > > +(with 'info' subcommand) when the image is used by a running guest. Note that > > +this could produce inconsistent result because of concurrent metadata changes, > > +etc. > > The documentation isn't clear on whether read-write is supported or just > read-only. > > Also, should it be declared a legacy option right away to discourage > use in new software? I don't think this is a legacy option. As long you know what you're doing, using it is fine. Kevin
On Fri, Dec 08, 2017 at 09:44:56AM +0800, Fam Zheng wrote: > Signed-off-by: Fam Zheng <famz@redhat.com> > > --- > v2: - "code{qemu-img}". [Kashyap, Eric] > - "etc.." -> "etc.". > --- > qemu-img.texi | 9 +++++++++ > 1 file changed, 9 insertions(+) Reviewed-by: Kashyap Chamarthy <kchamart@redhat.com> [...]
On Fri, 12/08 09:54, Stefan Hajnoczi wrote: > On Fri, Dec 08, 2017 at 09:44:56AM +0800, Fam Zheng wrote: > > +@item --force-share (-U) > > + > > +If specified, @code{qemu-img} will open the image with shared permissions, > > +which makes it less likely to conflict with a running guest's permissions due > > +to image locking. For example, this can be used to get the image information > > +(with 'info' subcommand) when the image is used by a running guest. Note that > > +this could produce inconsistent result because of concurrent metadata changes, > > +etc. > > The documentation isn't clear on whether read-write is supported or just > read-only. block.c will emit an error if used with read-write. I will add a sentence for that. Fam
diff --git a/qemu-img.texi b/qemu-img.texi index fdcf120f36..6b9f9adfc8 100644 --- a/qemu-img.texi +++ b/qemu-img.texi @@ -57,6 +57,15 @@ 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. +@item --force-share (-U) + +If specified, @code{qemu-img} will open the image with shared permissions, +which makes it less likely to conflict with a running guest's permissions due +to image locking. For example, this can be used to get the image information +(with 'info' subcommand) when the image is used by a running guest. Note that +this could produce inconsistent result because of concurrent metadata changes, +etc. + @item fmt is the disk image format. It is guessed automatically in most cases. See below for a description of the supported disk formats.
Signed-off-by: Fam Zheng <famz@redhat.com> --- v2: - "code{qemu-img}". [Kashyap, Eric] - "etc.." -> "etc.". --- qemu-img.texi | 9 +++++++++ 1 file changed, 9 insertions(+)