On 30.07.19 20:10, Eric Blake wrote: > On 7/30/19 12:25 PM, Max Reitz wrote: >> qcow2 v3 requires every snapshot table entry to have two extra data >> fields: The 64-bit VM state size, and the virtual disk size. Both are >> optional for v2 images, so they may not be present. >> >> qcow2_upgrade() therefore should update the snapshot table to ensure all >> entries have these extra data fields. >> >> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1727347 >> Reported-by: Eric Blake <ebl...@redhat.com> >> Signed-off-by: Max Reitz <mre...@redhat.com> >> --- >> block/qcow2.c | 29 +++++++++++++++++++++++++++-- >> 1 file changed, 27 insertions(+), 2 deletions(-) >> > >> + >> + /* >> + * In v2, snapshots do not need to have extra data. v3 requires >> + * the 64-bit VM state size and the virtual disk size to be >> + * present. >> + * qcow2_write_snapshots() will always write the list in the >> + * v3-compliant format. >> + */ >> + need_snapshot_update = false; >> + for (i = 0; i < s->nb_snapshots; i++) { >> + if (s->snapshots[i].extra_data_size < 16) { > > s/16/sizeof(extra)/ looks a bit nicer, but doesn't change semantics.
Hm, but it’s not quite right. I mean, right now it is, but if we were to add a new field to snapshot metadata, it wouldn’t be. It should be 16. I can make it something like sizeof(extra.vm_state_size_large) + sizeof(extra.disk_size), though. Max > Reviewed-by: Eric Blake <ebl...@redhat.com>
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