job: Convert block_job_cancel_async() to Job

block_job_cancel_async() did two things that were still block job
specific:

* Setting job->force. This field makes sense on the Job level, so we can
  just move it. While at it, rename it to job->force_cancel to make its
  purpose more obvious.

* Resetting the I/O status. This can't be moved because generic Jobs
  don't have an I/O status. What the function really implements is a
  user resume, except without entering the coroutine. Consequently, it
  makes sense to call the .user_resume driver callback here which
  already resets the I/O status.

  The old block_job_cancel_async() has two separate if statements that
  check job->iostatus != BLOCK_DEVICE_IO_STATUS_OK and job->user_paused.
  However, the former condition always implies the latter (as is
  asserted in block_job_iostatus_reset()), so changing the explicit call
  of block_job_iostatus_reset() on the former condition with the
  .user_resume callback on the latter condition is equivalent and
  doesn't need to access any BlockJob specific state.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

include/block/blockjob.h

@@ -50,12 +50,6 @@ typedef struct BlockJob {
     /** The block device on which the job is operating.  */
     BlockBackend *blk;
 
-    /**
-     * Set to true if the job should abort immediately without waiting
-     * for data to be in sync.
-     */
-    bool force;
-
     /**
      * Set to true when the job is ready to be completed.
      */

include/qemu/job.h

@@ -97,6 +97,12 @@ typedef struct Job {
      */
     bool cancelled;
 
+    /**
+     * Set to true if the job should abort immediately without waiting
+     * for data to be in sync.
+     */
+    bool force_cancel;
+
     /** Set to true when the job has deferred work to the main loop. */
     bool deferred_to_main_loop;