On 05/27/2014 08:28 AM, Jeff Cody wrote: > On some image chains, QEMU may not always be able to resolve the > filenames properly, when updating the backing file of an image > after a block commit. > > For instance, certain relative pathnames may fail, or drives may > have been specified originally by file descriptor (e.g. /dev/fd/???), > or a relative protocol pathname may have been used. > > In these instances, QEMU may lack the information to be able to make > the correct choice, but the user or management layer most likely does > have that knowledge. > > With this extension to the block-commit api, the user is able to change > the backing file of the overlay image as part of the block-commit > operation. > > This allows the change to be 'safe', in the sense that if the attempt > to write the overlay image metadata fails, then the block-commit > operation returns failure, without disrupting the guest. > > If the commit top is the active layer, then specifying the backing > file string will be treated as an error (there is no overlay image > to modify in that case). > > If a backing file string is not specified in the command, the backing > file string to use is determined in the same manner as it was > previously. > > Signed-off-by: Jeff Cody <jc...@redhat.com> > --- > block.c | 8 ++++++-- > block/commit.c | 9 ++++++--- > blockdev.c | 8 +++++++- > include/block/block.h | 3 ++- > include/block/block_int.h | 3 ++- > qapi-schema.json | 23 +++++++++++++++++++++-- > qmp-commands.hx | 19 ++++++++++++++++++- > 7 files changed, 62 insertions(+), 11 deletions(-) >
> +# @backing-file: #optional The backing file string to write into the overlay > +# image of 'top'. If 'top' is the active layer, > +# specifying a backing file string is an error. This > +# filename is not validated. > +# > +# If a pathname string is such that it cannot be > +# resolved be QEMU, that means that subsequent QMP > or s/be/by/ > +++ b/qmp-commands.hx > + If a pathname string is such that it cannot be > + resolved be QEMU, that means that subsequent QMP or and again If those two typo fixes are the only change, Reviewed-by: Eric Blake <ebl...@redhat.com> -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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