On Wed, Mar 06, 2013 at 07:31:51PM +0100, Paolo Bonzini wrote: > Il 06/03/2013 19:14, Jeff Cody ha scritto: > > QCOW breaks with it using a normal raw posix file as a device. As a > > test: qemu-img create -f qcow test.qcow 5G. Now run qemu with that > > drive mounted, and try to partition and format it. QEMU now asserts. > > > > The nicety of being able to using truncate during a write call, > > especially for VHDX (which can have relatively large block/cluster > > sizes), so to grow the file sparsely in a dynamically allocated file. > > Perhaps we need two APIs, "truncate" and "revalidate". > > Truncate should be a no-op if (!bs->growable). > > Revalidate could be called by the block_resize monitor command with no > size specified. > > Paolo
I think that is a good solution. Is it better to have "truncate" and "revalidate", or "truncate" and "grow", with grow being a subset of truncate, with fewer restrictions? There may still be operations where it is OK to grow a file, but not OK to shrink it.
