On Mon 16 Apr 2018 06:58:46 PM CEST, Max Reitz wrote: > Update the rest of the filter drivers to support > BDRV_REQ_WRITE_UNCHANGED. They already forward write request flags to > their children, so we just have to announce support for it. > > This patch does not cover the replication driver because that currently > does not support flags at all, and because it just grabs the WRITE > permission for its children when it can, so we should be fine just > submitting the incoming WRITE_UNCHANGED requests as normal writes. > > It also does not cover format drivers for similar reasons. They all use > bdrv_format_default_perms() as their .bdrv_child_perm() implementation > so they just always grab the WRITE permission for their file children > whenever possible. In addition, it often would be difficult to > ascertain whether incoming unchanging writes end up as unchanging writes > in their files. So we just leave them as normal potentially changing > writes. > > Signed-off-by: Max Reitz <mre...@redhat.com>
Reviewed-by: Alberto Garcia <be...@igalia.com> Berto
