[Qemu-devel] [PULL for-2.8 03/13] blockjob: add .start field

[Jeff Cody <jcody@redhat.com>]

From: John Snow <jsnow@redhat.com>

Add an explicit start field to specify the entrypoint. We already have
ownership of the coroutine itself AND managing the lifetime of the
coroutine, let's take control of creation of the coroutine, too.

This will allow us to delay creation of the actual coroutine until we
know we'll actually start a BlockJob in block_job_start. This avoids
the sticky question of how to "un-create" a Coroutine that hasn't been
started yet.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 1478587839-9834-4-git-send-email-jsnow@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
---
 block/backup.c               | 25 +++++++++++++------------
 block/commit.c               |  3 ++-
 block/mirror.c               |  4 +++-
 block/stream.c               |  3 ++-
 include/block/blockjob_int.h |  3 +++
 5 files changed, 23 insertions(+), 15 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index 734a24c..4ed4494 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -323,17 +323,6 @@ static void backup_drain(BlockJob *job)
     }
 }
 
-static const BlockJobDriver backup_job_driver = {
-    .instance_size          = sizeof(BackupBlockJob),
-    .job_type               = BLOCK_JOB_TYPE_BACKUP,
-    .set_speed              = backup_set_speed,
-    .commit                 = backup_commit,
-    .abort                  = backup_abort,
-    .clean                  = backup_clean,
-    .attached_aio_context   = backup_attached_aio_context,
-    .drain                  = backup_drain,
-};
-
 static BlockErrorAction backup_error_action(BackupBlockJob *job,
                                             bool read, int error)
 {
@@ -542,6 +531,18 @@ static void coroutine_fn backup_run(void *opaque)
     block_job_defer_to_main_loop(&job->common, backup_complete, data);
 }
 
+static const BlockJobDriver backup_job_driver = {
+    .instance_size          = sizeof(BackupBlockJob),
+    .job_type               = BLOCK_JOB_TYPE_BACKUP,
+    .start                  = backup_run,
+    .set_speed              = backup_set_speed,
+    .commit                 = backup_commit,
+    .abort                  = backup_abort,
+    .clean                  = backup_clean,
+    .attached_aio_context   = backup_attached_aio_context,
+    .drain                  = backup_drain,
+};
+
 void backup_start(const char *job_id, BlockDriverState *bs,
                   BlockDriverState *target, int64_t speed,
                   MirrorSyncMode sync_mode, BdrvDirtyBitmap *sync_bitmap,
@@ -653,7 +654,7 @@ void backup_start(const char *job_id, BlockDriverState *bs,
 
     block_job_add_bdrv(&job->common, target);
     job->common.len = len;
-    job->common.co = qemu_coroutine_create(backup_run, job);
+    job->common.co = qemu_coroutine_create(job->common.driver->start, job);
     block_job_txn_add_job(txn, &job->common);
     qemu_coroutine_enter(job->common.co);
     return;
diff --git a/block/commit.c b/block/commit.c
index e1eda89..20d27e2 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -205,6 +205,7 @@ static const BlockJobDriver commit_job_driver = {
     .instance_size = sizeof(CommitBlockJob),
     .job_type      = BLOCK_JOB_TYPE_COMMIT,
     .set_speed     = commit_set_speed,
+    .start         = commit_run,
 };
 
 void commit_start(const char *job_id, BlockDriverState *bs,
@@ -288,7 +289,7 @@ void commit_start(const char *job_id, BlockDriverState *bs,
     s->backing_file_str = g_strdup(backing_file_str);
 
     s->on_error = on_error;
-    s->common.co = qemu_coroutine_create(commit_run, s);
+    s->common.co = qemu_coroutine_create(s->common.driver->start, s);
 
     trace_commit_start(bs, base, top, s, s->common.co);
     qemu_coroutine_enter(s->common.co);
diff --git a/block/mirror.c b/block/mirror.c
index b2c1fb8..659e09c 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -920,6 +920,7 @@ static const BlockJobDriver mirror_job_driver = {
     .instance_size          = sizeof(MirrorBlockJob),
     .job_type               = BLOCK_JOB_TYPE_MIRROR,
     .set_speed              = mirror_set_speed,
+    .start                  = mirror_run,
     .complete               = mirror_complete,
     .pause                  = mirror_pause,
     .attached_aio_context   = mirror_attached_aio_context,
@@ -930,6 +931,7 @@ static const BlockJobDriver commit_active_job_driver = {
     .instance_size          = sizeof(MirrorBlockJob),
     .job_type               = BLOCK_JOB_TYPE_COMMIT,
     .set_speed              = mirror_set_speed,
+    .start                  = mirror_run,
     .complete               = mirror_complete,
     .pause                  = mirror_pause,
     .attached_aio_context   = mirror_attached_aio_context,
@@ -1007,7 +1009,7 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
         }
     }
 
-    s->common.co = qemu_coroutine_create(mirror_run, s);
+    s->common.co = qemu_coroutine_create(s->common.driver->start, s);
     trace_mirror_start(bs, s, s->common.co, opaque);
     qemu_coroutine_enter(s->common.co);
 }
diff --git a/block/stream.c b/block/stream.c
index b05856b..92309ff 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -218,6 +218,7 @@ static const BlockJobDriver stream_job_driver = {
     .instance_size = sizeof(StreamBlockJob),
     .job_type      = BLOCK_JOB_TYPE_STREAM,
     .set_speed     = stream_set_speed,
+    .start         = stream_run,
 };
 
 void stream_start(const char *job_id, BlockDriverState *bs,
@@ -254,7 +255,7 @@ void stream_start(const char *job_id, BlockDriverState *bs,
     s->bs_flags = orig_bs_flags;
 
     s->on_error = on_error;
-    s->common.co = qemu_coroutine_create(stream_run, s);
+    s->common.co = qemu_coroutine_create(s->common.driver->start, s);
     trace_stream_start(bs, base, s, s->common.co);
     qemu_coroutine_enter(s->common.co);
 }
diff --git a/include/block/blockjob_int.h b/include/block/blockjob_int.h
index 60d91a0..8223822 100644
--- a/include/block/blockjob_int.h
+++ b/include/block/blockjob_int.h
@@ -47,6 +47,9 @@ struct BlockJobDriver {
     /** Optional callback for job types that need to forward I/O status reset */
     void (*iostatus_reset)(BlockJob *job);
 
+    /** Mandatory: Entrypoint for the Coroutine. */
+    CoroutineEntry *start;
+
     /**
      * Optional callback for job types whose completion must be triggered
      * manually.
-- 
2.7.4