Am 28.06.2013 um 10:25 hat Peter Lieven geschrieben: > On 28.06.2013 10:20, Kevin Wolf wrote: > >Am 28.06.2013 um 10:16 hat Peter Lieven geschrieben: > >>On 28.06.2013 10:06, Kevin Wolf wrote: > >>>Am 27.06.2013 um 15:52 hat Peter Lieven geschrieben: > >>>>.has_zero_init defaults to 1 for all formats and protocols. > >>>> > >>>>this is a dangerous default since this means that all > >>>>new added drivers need to manually overwrite it to 0 if > >>>>they do not ensure that a device is zero initialized > >>>>after bdrv_create(). > >>>> > >>>>if a driver needs to explicitly set this value to > >>>>1 its easier to verify the correctness in the review process. > >>>> > >>>>during review of the existing drivers it turned out > >>>>that ssh and gluster had a wrong default of 1. > >>>>both protocols support host_devices as backend > >>>>which are not by default zero initialized. this > >>>>wrong assumption will lead to possible corruption > >>>>if qemu-img convert is used to write to such a backend. > >>>> > >>>>a similar problem with the wrong default existed for > >>>>iscsi mose likely because the driver developer did > >>>>oversee the default value of 1. > >>>> > >>>>Signed-off-by: Peter Lieven <p...@kamp.de> > >>>>--- > >>>> block.c | 8 +++++++- > >>>> block/qcow.c | 1 + > >>>> block/qcow2.c | 1 + > >>>> block/qed.c | 1 + > >>>> block/raw-posix.c | 10 +--------- > >>>> block/raw-win32.c | 7 +------ > >>>> block/rbd.c | 1 + > >>>> block/sheepdog.c | 1 + > >>>> block/vdi.c | 1 + > >>>> block/vmdk.c | 1 + > >>>> include/block/block.h | 1 + > >>>> 11 files changed, 17 insertions(+), 16 deletions(-) > >>>You forgot cow, which is also a simple case that can be handled in this > >>>patch. > >>ups. > >>>vpc is still easy, but a bit more complicated than a constant return 1, > >>>because it depends on the subformat whether a new image will inherit the > >>>has_zero_init property from the underlying storage or whether it always > >>>produces zeros (for VHD_FIXED type images, it's basically raw + footer). > >>>I'll send a separate patch for this. > >>shall I leave this to the new 0 default until your patch is ready? > >Yes, please leave vpc alone. I guess my patch will be queued before > >yours anyway. ;-) > once v2 is ready and noone has objections maybe you can put it in your queue? > ;-)
Sure. I'm going to send a pull request today, so it would be good to have v2 of this patch soon. (Otherwise it would have to wait for Stefan's pull request probably next Friday) Kevin
