tree 1e5e0ad62a471991aad9ac38630aa7a88ca62dff
parent 0b919fae31f4f80f78ebeab8388dc3a03cc5e4ed
author Kevin Wolf <kwolf@redhat.com> 1371642261 +0200
committer Stefan Hajnoczi <stefanha@redhat.com> 1372062317 +0200

block: Always enable discard on the protocol level

Turning on discard options in qcow2 doesn't help a lot when the discard
requests that it issues are thrown away by the raw-posix layer. This
patch always enables discard functionality on the protocol level so that
it's the image format's responsibility to send (or not) discard
requests. Requests sent by the guest will be allowed or ignored by the
top level BlockDriverState, which depends on the discard=... option like
before.

In particular, this means that even without specifying options, the
qcow2 default of discarding deleted snapshots actually takes effect now,
both for qemu and qemu-img.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>