block: Turn on "unmap" in active commit
commit6f13acf97efb8aade2ff7e0444c15512f9e65812
authorFam Zheng <famz@redhat.com>
Tue, 27 Sep 2016 11:14:52 +0000 (27 19:14 +0800)
committerJeff Cody <jcody@redhat.com>
Tue, 1 Nov 2016 11:55:57 +0000 (1 07:55 -0400)
tree24932aff3fc5b983d2b2e25703bbc34c36d2a92b
parent6349c15410361d3fe52c9beee309954d606f8ccd
block: Turn on "unmap" in active commit

We already specified BDRV_O_UNMAP when opening images in 'qemu-img
commit', but didn't turn on the "unmap" in the active commit job. This
patch fixes that so that zeroed clusters in top image can be discarded
which is desired in the virt-sparsify use case, where a temporary
overlay is created and fstrim'ed before commiting back, to free space in
the original image.

This also enables it for block-commit.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 1474974892-5031-1-git-send-email-famz@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
block/mirror.c