[Qemu-block] [PATCH 1/3] block: prohibit migration during BlockJobs

[John Snow]

Unless we can prove this to be safe for specific cases,
the default should be to prohibit migration during BlockJobs.

In conjunction with
"migration: disallow_migrate_add_blocker during migration",
this should be sufficient to disallow the blockjob from starting
in the event of an in-progress migration.

Signed-off-by: John Snow <address@hidden>
---
 blockjob.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/blockjob.c b/blockjob.c
index 62bb906..b5849b3 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -35,12 +35,14 @@
 #include "qmp-commands.h"
 #include "qemu/timer.h"
 #include "qapi-event.h"
+#include "migration/migration.h"
 
 void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
                        int64_t speed, BlockCompletionFunc *cb,
                        void *opaque, Error **errp)
 {
     BlockJob *job;
+    int ret;
 
     if (bs->job) {
         error_setg(errp, QERR_DEVICE_IN_USE, bdrv_get_device_name(bs));
@@ -71,6 +73,14 @@ void *block_job_create(const BlockJobDriver *driver, 
BlockDriverState *bs,
             return NULL;
         }
     }
+
+    /* Re-use the op-blocker as a migration blocker */
+    ret = migrate_add_blocker(job->blocker, errp);
+    if (ret < 0) {
+        block_job_release(bs);
+        return NULL;
+    }
+
     return job;
 }
 
@@ -80,6 +90,7 @@ void block_job_release(BlockDriverState *bs)
 
     bs->job = NULL;
     bdrv_op_unblock_all(bs, job->blocker);
+    migrate_del_blocker(job->blocker);
     error_free(job->blocker);
     g_free(job);
 }
-- 
2.4.3