blockjob: Store device name at job creation

Some block jobs change the block device graph on completion. This means
that the device that owns the job and originally was addressed with its
device name may no longer be what the corresponding BlockBackend points
to.

Previously, the effects of bdrv_swap() ensured that the job was (at
least partially) transferred to the target image. Events that contain
the device name could still use bdrv_get_device_name(job->bs) and get
the same result.

After removing bdrv_swap(), this won't work any more. Instead, save the
device name at job creation and use that copy for QMP events and
anything else identifying the job.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>

block/mirror.c

@@ -645,8 +645,7 @@ static void mirror_complete(BlockJob *job, Error **errp)
         return;
     }
     if (!s->synced) {
-        error_setg(errp, QERR_BLOCK_JOB_NOT_READY,
-                   bdrv_get_device_name(job->bs));
+        error_setg(errp, QERR_BLOCK_JOB_NOT_READY, job->id);
         return;
     }
 

blockjob.c

@@ -54,6 +54,7 @@ void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
     bdrv_op_unblock(bs, BLOCK_OP_TYPE_DATAPLANE, job->blocker);
 
     job->driver        = driver;
+    job->id            = g_strdup(bdrv_get_device_name(bs));
     job->bs            = bs;
     job->cb            = cb;
     job->opaque        = opaque;
@@ -81,6 +82,7 @@ void block_job_release(BlockDriverState *bs)
     bs->job = NULL;
     bdrv_op_unblock_all(bs, job->blocker);
     error_free(job->blocker);
+    g_free(job->id);
     g_free(job);
 }
 
@@ -113,8 +115,7 @@ void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp)
 void block_job_complete(BlockJob *job, Error **errp)
 {
     if (job->pause_count || job->cancelled || !job->driver->complete) {
-        error_setg(errp, QERR_BLOCK_JOB_NOT_READY,
-                   bdrv_get_device_name(job->bs));
+        error_setg(errp, QERR_BLOCK_JOB_NOT_READY, job->id);
         return;
     }
 
@@ -269,7 +270,7 @@ BlockJobInfo *block_job_query(BlockJob *job)
 {
     BlockJobInfo *info = g_new0(BlockJobInfo, 1);
     info->type      = g_strdup(BlockJobType_lookup[job->driver->job_type]);
-    info->device    = g_strdup(bdrv_get_device_name(job->bs));
+    info->device    = g_strdup(job->id);
     info->len       = job->len;
     info->busy      = job->busy;
     info->paused    = job->pause_count > 0;
@@ -291,7 +292,7 @@ static void block_job_iostatus_set_err(BlockJob *job, int error)
 void block_job_event_cancelled(BlockJob *job)
 {
     qapi_event_send_block_job_cancelled(job->driver->job_type,
-                                        bdrv_get_device_name(job->bs),
+                                        job->id,
                                         job->len,
                                         job->offset,
                                         job->speed,
@@ -301,7 +302,7 @@ void block_job_event_cancelled(BlockJob *job)
 void block_job_event_completed(BlockJob *job, const char *msg)
 {
     qapi_event_send_block_job_completed(job->driver->job_type,
-                                        bdrv_get_device_name(job->bs),
+                                        job->id,
                                         job->len,
                                         job->offset,
                                         job->speed,
@@ -315,7 +316,7 @@ void block_job_event_ready(BlockJob *job)
     job->ready = true;
 
     qapi_event_send_block_job_ready(job->driver->job_type,
-                                    bdrv_get_device_name(job->bs),
+                                    job->id,
                                     job->len,
                                     job->offset,
                                     job->speed, &error_abort);
@@ -344,7 +345,7 @@ BlockErrorAction block_job_error_action(BlockJob *job, BlockDriverState *bs,
     default:
         abort();
     }
-    qapi_event_send_block_job_error(bdrv_get_device_name(job->bs),
+    qapi_event_send_block_job_error(job->id,
                                     is_read ? IO_OPERATION_TYPE_READ :
                                     IO_OPERATION_TYPE_WRITE,
                                     action, &error_abort);

include/block/blockjob.h

@@ -64,6 +64,14 @@ struct BlockJob {
     /** The block device on which the job is operating.  */
     BlockDriverState *bs;
 
+    /**
+     * The ID of the block job. Currently the BlockBackend name of the BDS
+     * owning the job at the time when the job is started.
+     *
+     * TODO Decouple block job IDs from BlockBackend names
+     */
+    char *id;
+
     /**
      * The coroutine that executes the job.  If not NULL, it is
      * reentered when busy is false and the job is cancelled.