On Fri, Mar 14, 2014 at 01:47:59PM +0100, Paolo Bonzini wrote: > Il 14/03/2014 13:42, Richard W.M. Jones ha scritto: > >I worked around this in any case by rearranging the test [2]: > > > >Doing: > > > > rm /a_big_file > > fstrim / > > sync > > umount / > > [shut down qemu] > > > >would only trim 64 KB on the host. > > > >Doing: > > > > rm /a_big_file > > umount / # added > > mount -o nodiscard /dev/sda / # added > > fstrim / > > sync > > umount / > > [shut down qemu] > > > >would trim the expected amount (around 10 MB). > > > >I've no idea why this is (looks like an ext4/kernel bug to me), but in > >any case the tests now use the second method[2]. > > Could be a race condition (something going on in the background > between rm and fstrim).
Not much happens in the libguestfs appliance. There are usually only two processes (udev + guestfsd). > Try syncing before fstrim, not after. In > fact the sync before umount should not be necessary. Yes, that works with both upstream kernel+qemu and with F21 kernel+qemu. https://github.com/libguestfs/libguestfs/commit/d46ceea6014006ab19b6f795e2e28a7360d90b2c Thanks, Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org
