It does not currently appear to be possible to attach/detach a filesystem with kvm through the C API or virsh. Looking at src/qemu/qemu_driver.c:qemuDomain{Attach,Detach,Update}Config, VIR_DOMAIN_DEVICE_FS is not a case within the switch statement for dev->type.
Is support for this planned for the near future or in progress? If not, how much would have to be implemented outside these functions to add support for attaching, detaching, and modifying filesystems? I would like to gauge whether I should carve out time to add support, or work around it by using disks in place of filesystems. Thanks!
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Jesse J. Cook
Camber Corporation
Lead Software Developer