blockjobs: add block_job_dismiss

For jobs that have reached their CONCLUDED state, prior to having their
last reference put down (meaning jobs that have completed successfully,
unsuccessfully, or have been canceled), allow the user to dismiss the
job's lingering status report via block-job-dismiss.

This gives management APIs the chance to conclusively determine if a job
failed or succeeded, even if the event broadcast was missed.

Note: block_job_do_dismiss and block_job_decommission happen to do
exactly the same thing, but they're called from different semantic
contexts, so both aliases are kept to improve readability.

Note 2: Don't worry about the 0x04 flag definition for AUTO_DISMISS, she
has a friend coming in a future patch to fill the hole where 0x02 is.

Verbs:
Dismiss: operates on CONCLUDED jobs only.
Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 24 insertions, 2 deletions

diff --git a/blockjob.c b/blockjob.c
index 2ef48075b0..59ac4a13c7 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -63,6 +63,7 @@ bool BlockJobVerbTable[BLOCK_JOB_VERB__MAX][BLOCK_JOB_STATUS__MAX] = {
     [BLOCK_JOB_VERB_RESUME]               = {0, 1, 1, 1, 1, 1, 0, 0, 0},
     [BLOCK_JOB_VERB_SET_SPEED]            = {0, 1, 1, 1, 1, 1, 0, 0, 0},
     [BLOCK_JOB_VERB_COMPLETE]             = {0, 0, 0, 0, 1, 0, 0, 0, 0},
+    [BLOCK_JOB_VERB_DISMISS]              = {0, 0, 0, 0, 0, 0, 0, 1, 0},
 };
 
 static void block_job_state_transition(BlockJob *job, BlockJobStatus s1)
@@ -391,9 +392,17 @@ static void block_job_decommission(BlockJob *job)
     block_job_unref(job);
 }
 
+static void block_job_do_dismiss(BlockJob *job)
+{
+    block_job_decommission(job);
+}
+
 static void block_job_conclude(BlockJob *job)
 {
     block_job_state_transition(job, BLOCK_JOB_STATUS_CONCLUDED);
+    if (job->auto_dismiss || !block_job_started(job)) {
+        block_job_do_dismiss(job);
+    }
 }
 
 static void block_job_completed_single(BlockJob *job)
@@ -437,7 +446,6 @@ static void block_job_completed_single(BlockJob *job)
     QLIST_REMOVE(job, txn_list);
     block_job_txn_unref(job->txn);
     block_job_conclude(job);
-    block_job_decommission(job);
 }
 
 static void block_job_cancel_async(BlockJob *job)
@@ -602,6 +610,19 @@ void block_job_complete(BlockJob *job, Error **errp)
     job->driver->complete(job, errp);
 }
 
+void block_job_dismiss(BlockJob **jobptr, Error **errp)
+{
+    BlockJob *job = *jobptr;
+    /* similarly to _complete, this is QMP-interface only. */
+    assert(job->id);
+    if (block_job_apply_verb(job, BLOCK_JOB_VERB_DISMISS, errp)) {
+        return;
+    }
+
+    block_job_do_dismiss(job);
+    *jobptr = NULL;
+}
+
 void block_job_user_pause(BlockJob *job, Error **errp)
 {
     if (block_job_apply_verb(job, BLOCK_JOB_VERB_PAUSE, errp)) {
@@ -638,7 +659,7 @@ void block_job_user_resume(BlockJob *job, Error **errp)
 void block_job_cancel(BlockJob *job)
 {
     if (job->status == BLOCK_JOB_STATUS_CONCLUDED) {
-        return;
+        block_job_do_dismiss(job);
     } else if (block_job_started(job)) {
         block_job_cancel_async(job);
         block_job_enter(job);
@@ -807,6 +828,7 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver,
     job->paused        = true;
     job->pause_count   = 1;
     job->refcnt        = 1;
+    job->auto_dismiss  = !(flags & BLOCK_JOB_MANUAL_DISMISS);
     block_job_state_transition(job, BLOCK_JOB_STATUS_CREATED);
     aio_timer_init(qemu_get_aio_context(), &job->sleep_timer,
                    QEMU_CLOCK_REALTIME, SCALE_NS,