vmdk: Allow vmdk_create to work with protocol

This improves vmdk_create to use bdrv_* functions to replace qemu_open
and other fd functions. The error handling are improved as well. One
difference is that bdrv_pwrite will round up buffer to sectors, so for
description file, an extra bdrv_truncate is used in the end to drop
inding zeros.

Notes:

 - A bonus bug fix is correct endian is used in initializing GD entries.

 - ROUND_UP and DIV_ROUND_UP are used where possible.

I tested that new code produces exactly the same file as previously.

Signed-off-by: Fam Zheng <famz@redhat.com>
Tested-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
qemu-iotests: drop duplicate virtio-blk initialization failure

Commit 75884afd5c6c42e523b08565e289dbe319e17ad9 ("virtio-blk: Convert to
QOM realize") dropped a duplicate error_report() call.  Now we no longer
get the following error message twice:

  QEMU_PROG: -drive if=virtio: Device initialization failed.

Update qemu-iotests 051.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
mirror: Don't close target

Let reference count manage target and don't call bdrv_close here.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
mirror: Move base to MirrorBlockJob

This allows setting the base before entering mirror_run, commit will
make use of it.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
block: Add commit_active_start()

commit_active_start is implemented in block/mirror.c, It will create a
job with "commit" type and designated base in block-commit command. This
will be used for committing active layer of device.

Sync mode is removed from MirrorBlockJob because there's no proper type
for commit. The used information is is_none_mode.

The common part of mirror_start and commit_active_start is moved to
mirror_start_job().

Fix the comment wording for commit_start.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
commit: Support commit active layer

If active is top, it will be mirrored to base, (with block/mirror.c
code), then the image is switched when user completes the block job.

QMP documentation is updated.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
qemu-iotests: Update test cases for commit active

Factor out commit test common logic into super class, and update test
of committing the active image.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
commit: Remove unused check

We support top == active for commit now, remove the check and add an
assertion here.

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