mirror: Fix resource leak when bdrv_getlength fails

The direct return will skip releasing of all the resouces at
immediate_exit, don't miss that.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 373df5b135b4a54e0abb394e9e703fef3ded093c)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
blockjob: Add block_job_yield()

This will unset busy flag and put coroutine to sleep, can be used to
wait for QMP complete/cancel.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit dc71ce45ded4e872e25c2de32d5e7a71842b0985)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
mirror: Go through ready -> complete process for 0 len image

When mirroring or active committing a zero length image, BLOCK_JOB_READY
is not reported now, instead the job completes because we short circuit
the mirror job loop.

This is inconsistent with non-zero length images, and only confuses
management software.

Let's do the same thing when seeing a 0-length image: report ready
immediately; wait for block-job-cancel or block-job-complete; clear the
cancel flag as existing non-zero image synced case (cancelled after
ready); then jump to the exit.

Reported-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 9e48b025400b2d284e17860862b0a4aa02c6032d)

*removed dependency on bcada37b

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
qemu-iotests: Test BLOCK_JOB_READY event for 0Kb image active commit

There should be a BLOCK_JOB_READY event with active commit, regardless
of image length. Let's test the 0 length image case, and make sure it
goes through the ready->complete process.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 8b9a30ca5bc10545637429486836f3c206c39fab)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
block: make 'top' argument to block-commit optional

Now that active layer block-commit is supported, the 'top' argument
no longer needs to be mandatory.

Change it to optional, with the default being the active layer in the
device chain.

[kwolf: Rebased and resolved conflict in tests/qemu-iotests/040]

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 7676e2c597000eff3a7233b40cca768b358f9bc9)

Conflicts:
	qapi/block-core.json

*removed dependency on 1ad166b6

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>