On Mon, Feb 27, 2012 at 3:23 PM, Jeff Cody <jc...@redhat.com> wrote: > On 02/27/2012 09:40 AM, Stefan Hajnoczi wrote: >> On Mon, Feb 27, 2012 at 2:26 PM, Jeff Cody <jc...@redhat.com> wrote: >>> On 02/27/2012 06:13 AM, Stefan Hajnoczi wrote: >>>> On Sun, Feb 26, 2012 at 7:31 PM, Jeff Cody <jc...@redhat.com> wrote: >>>>> + * It is assumed that bs_new already points to an existing image, >>>>> + * with the correct backing filename of top->backing_file >>>> >>>> Not sure what this means. Isn't bs_new going to use bs_top as its >>>> backing file? Why "top->backing_file"? >>> >>> Sorry, that should have been 'bs_top->backing_file'. The image file is >>> not created by this function. I added some more explanation, and >>> corrected that typo, in the above comment block. Let me know if you >>> think it still needs more clarification. >> >> I still don't follow. Old bs_top's image file itself becomes the >> backing file, not bs_top->backing_file. Perhaps I'm misinterpreting >> because of how swap changes bs_top and bs_new, but I'm reading it from >> the perspective of the caller when they pass in bs_top. >> > > Maybe it would be better to just replace that part of the comment with > something that says "This function does not create the image file". > > The function bdrv_append() will neither create the image file, or set > (in the case of qcow2) the extended headers of the file to have the > backing filename. It is only concerned with the bs contents.
Makes sense. Stefan
