On 5/11/26 22:37, Peter Krempa wrote: > On Mon, May 11, 2026 at 22:21:35 +0200, Denis V. Lunev wrote: >> qemuDomainBlockResize() issues block_resize via QMP, which updates the >> qcow2 header on disk and bs->total_sectors in qemu, but the cached >> disk->src->capacity in libvirt is left at its pre-resize value. >> >> All current readers re-read capacity from either QMP or the file itself >> before returning to the user, so the staleness is not externally >> observable today. Still, the cached field should reflect what we just >> asked qemu to write; keeping the two in sync avoids surprises for any >> future consumer that trusts the cached value. > None of those values are stored in the status XML so they will be > missing in certain situations. Each caller who wants to read the > 'capacity', 'allocation' or 'physical' field *must* update it before any > read. > > The commit message doesn't IMO provide enough justification to do this > since each caller will update it. > we have faced problem in downstream with a surprise that this value is stale but that could be not a very good reason to make this in.
Would it worth to make a comment in the header instead that this value is unreliable and should be re-read? Den
