Am 06.03.2013 19:48, schrieb Jeff Cody: > 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. >
Or as a first step: a) Call brdv_drain_all() only if the device is shrinked (independently of !bs->growable) b) Call brdv_drain_all() inside iscsi_truncate() because it is a special requirement there c) Fix the value of bs->growable for all drivers Peter
