block: Always enable discard on the protocol level

Enterprise / Virtualization / QEMU - Kevin Wolf [redhat.com] - 24 June 2013 03:25 UTC

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.

50b05b6 block: Always enable discard on the protocol level
block.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

Upstream: git.qemu.org

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