block/mirror: Add MirrorBDSOpaque

This will allow us to access the block job data when the mirror block
driver becomes more complex.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 20180613181823.13618-11-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

block/mirror.c

@@ -76,6 +76,10 @@ typedef struct MirrorBlockJob {
     bool initial_zeroing_ongoing;
 } MirrorBlockJob;
 
+typedef struct MirrorBDSOpaque {
+    MirrorBlockJob *job;
+} MirrorBDSOpaque;
+
 struct MirrorOp {
     MirrorBlockJob *s;
     QEMUIOVector qiov;
@@ -599,6 +603,7 @@ static void mirror_exit(Job *job, void *opaque)
     MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job);
     BlockJob *bjob = &s->common;
     MirrorExitData *data = opaque;
+    MirrorBDSOpaque *bs_opaque = s->mirror_top_bs->opaque;
     AioContext *replace_aio_context = NULL;
     BlockDriverState *src = s->mirror_top_bs->backing->bs;
     BlockDriverState *target_bs = blk_bs(s->target);
@@ -691,6 +696,7 @@ static void mirror_exit(Job *job, void *opaque)
     blk_set_perm(bjob->blk, 0, BLK_PERM_ALL, &error_abort);
     blk_insert_bs(bjob->blk, mirror_top_bs, &error_abort);
 
+    bs_opaque->job = NULL;
     job_completed(job, data->ret, NULL);
 
     g_free(data);
@@ -1230,6 +1236,7 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
                              Error **errp)
 {
     MirrorBlockJob *s;
+    MirrorBDSOpaque *bs_opaque;
     BlockDriverState *mirror_top_bs;
     bool target_graph_mod;
     bool target_is_backing;
@@ -1265,6 +1272,8 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
     mirror_top_bs->total_sectors = bs->total_sectors;
     mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED;
     mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED;
+    bs_opaque = g_new0(MirrorBDSOpaque, 1);
+    mirror_top_bs->opaque = bs_opaque;
     bdrv_set_aio_context(mirror_top_bs, bdrv_get_aio_context(bs));
 
     /* bdrv_append takes ownership of the mirror_top_bs reference, need to keep
@@ -1289,6 +1298,8 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
     if (!s) {
         goto fail;
     }
+    bs_opaque->job = s;
+
     /* The block job now has a reference to this node */
     bdrv_unref(mirror_top_bs);
 
@@ -1378,6 +1389,7 @@ fail:
 
         g_free(s->replaces);
         blk_unref(s->target);
+        bs_opaque->job = NULL;
         job_early_fail(&s->common.job);
     }