[Qemu-block] [PATCH 2/5] blockjob: add block_job_start

[John Snow]

Instead of automatically starting jobs at creation time via backup_start
et al, we'd like to return a job object pointer that can be started
manually at later point in time.

For now, add the block_job_start mechanism and start the jobs
automatically as we have been doing, with conversions job-by-job coming
in later patches.

Signed-off-by: John Snow <address@hidden>
---
 block/backup.c            |  2 +-
 block/commit.c            |  2 +-
 block/mirror.c            |  2 +-
 block/stream.c            |  2 +-
 blockjob.c                | 11 ++++++++++-
 include/block/blockjob.h  |  8 ++++++++
 tests/test-blockjob-txn.c |  2 +-
 7 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index 2c05323..2229e26 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -578,7 +578,7 @@ void backup_start(const char *job_id, BlockDriverState *bs,
     job->common.len = len;
     job->common.co = qemu_coroutine_create(backup_run, job);
     block_job_txn_add_job(txn, &job->common);
-    qemu_coroutine_enter(job->common.co);
+    block_job_start(&job->common);
     return;
 
  error:
diff --git a/block/commit.c b/block/commit.c
index 553e18d..f93864a 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -278,7 +278,7 @@ void commit_start(const char *job_id, BlockDriverState *bs,
     s->common.co = qemu_coroutine_create(commit_run, s);
 
     trace_commit_start(bs, base, top, s, s->common.co, opaque);
-    qemu_coroutine_enter(s->common.co);
+    block_job_start(&s->common);
 }
 
 
diff --git a/block/mirror.c b/block/mirror.c
index e0b3f41..79d9b84 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -965,7 +965,7 @@ static void mirror_start_job(const char *job_id, 
BlockDriverState *bs,
 
     s->common.co = qemu_coroutine_create(mirror_run, s);
     trace_mirror_start(bs, s, s->common.co, opaque);
-    qemu_coroutine_enter(s->common.co);
+    block_job_start(&s->common);
 }
 
 void mirror_start(const char *job_id, BlockDriverState *bs,
diff --git a/block/stream.c b/block/stream.c
index 3187481..c2a8a3e 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -233,5 +233,5 @@ void stream_start(const char *job_id, BlockDriverState *bs,
     s->on_error = on_error;
     s->common.co = qemu_coroutine_create(stream_run, s);
     trace_stream_start(bs, base, s, s->common.co, opaque);
-    qemu_coroutine_enter(s->common.co);
+    block_job_start(&s->common);
 }
diff --git a/blockjob.c b/blockjob.c
index e045091..0d07abc 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -158,7 +158,8 @@ void *block_job_create(const char *job_id, const 
BlockJobDriver *driver,
     job->blk           = blk;
     job->cb            = cb;
     job->opaque        = opaque;
-    job->busy          = true;
+    job->busy          = false;
+    job->paused        = true;
     job->refcnt        = 1;
     bs->job = job;
 
@@ -181,6 +182,14 @@ void *block_job_create(const char *job_id, const 
BlockJobDriver *driver,
     return job;
 }
 
+void block_job_start(BlockJob *job)
+{
+    assert(job && job->co && job->paused && !job->busy);
+    job->paused = false;
+    job->busy = true;
+    qemu_coroutine_enter(job->co);
+}
+
 void block_job_ref(BlockJob *job)
 {
     ++job->refcnt;
diff --git a/include/block/blockjob.h b/include/block/blockjob.h
index 4ddb4ae..e06258f 100644
--- a/include/block/blockjob.h
+++ b/include/block/blockjob.h
@@ -246,6 +246,14 @@ void *block_job_create(const char *job_id, const 
BlockJobDriver *driver,
                        BlockCompletionFunc *cb, void *opaque, Error **errp);
 
 /**
+ * block_job_start:
+ * @job: The job object as returned by @block_job_create.
+ *
+ * Begins execution of a block job.
+ */
+void block_job_start(BlockJob *job);
+
+/**
  * block_job_sleep_ns:
  * @job: The job that calls the function.
  * @clock: The clock to sleep on.
diff --git a/tests/test-blockjob-txn.c b/tests/test-blockjob-txn.c
index d049cba..8399f62 100644
--- a/tests/test-blockjob-txn.c
+++ b/tests/test-blockjob-txn.c
@@ -106,7 +106,7 @@ static BlockJob *test_block_job_start(unsigned int 
iterations,
     s->common.co = qemu_coroutine_create(test_block_job_run, s);
     data->job = s;
     data->result = result;
-    qemu_coroutine_enter(s->common.co);
+    block_job_start(&s->common);
     return &s->common;
 }
 
-- 
2.7.4