blockjobs: model single jobs as transactions

model all independent jobs as single job transactions.

It's one less case we have to worry about when we add more states to the
transition machine. This way, we can just treat all job lifetimes exactly
the same. This helps tighten assertions of the STM graph and removes some
conditionals that would have been needed in the coming commits adding a
more explicit job lifetime management API.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 16 insertions, 9 deletions

diff --git a/blockjob.c b/blockjob.c
index afd92db01f..ecc5fcbdf8 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -357,10 +357,8 @@ static void block_job_completed_single(BlockJob *job)
         }
     }
 
-    if (job->txn) {
-        QLIST_REMOVE(job, txn_list);
-        block_job_txn_unref(job->txn);
-    }
+    QLIST_REMOVE(job, txn_list);
+    block_job_txn_unref(job->txn);
     block_job_unref(job);
 }
 
@@ -647,7 +645,7 @@ static void block_job_event_completed(BlockJob *job, const char *msg)
  */
 
 void *block_job_create(const char *job_id, const BlockJobDriver *driver,
-                       BlockDriverState *bs, uint64_t perm,
+                       BlockJobTxn *txn, BlockDriverState *bs, uint64_t perm,
                        uint64_t shared_perm, int64_t speed, int flags,
                        BlockCompletionFunc *cb, void *opaque, Error **errp)
 {
@@ -729,6 +727,17 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver,
             return NULL;
         }
     }
+
+    /* Single jobs are modeled as single-job transactions for sake of
+     * consolidating the job management logic */
+    if (!txn) {
+        txn = block_job_txn_new();
+        block_job_txn_add_job(txn, job);
+        block_job_txn_unref(txn);
+    } else {
+        block_job_txn_add_job(txn, job);
+    }
+
     return job;
 }
 
@@ -752,13 +761,11 @@ void block_job_early_fail(BlockJob *job)
 
 void block_job_completed(BlockJob *job, int ret)
 {
+    assert(job && job->txn && !job->completed);
     assert(blk_bs(job->blk)->job == job);
-    assert(!job->completed);
     job->completed = true;
     job->ret = ret;
-    if (!job->txn) {
-        block_job_completed_single(job);
-    } else if (ret < 0 || block_job_is_cancelled(job)) {
+    if (ret < 0 || block_job_is_cancelled(job)) {
         block_job_completed_txn_abort(job);
     } else {
         block_job_completed_txn_success(job);