[PATCH v7 2/7] block/export: add blk_by_export_id()

[Vladimir Sementsov-Ogievskiy]

We need it for further blockdev-replace functionality.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
---
 block/export/export.c                       | 18 ++++++++++++++++++
 include/sysemu/block-backend-global-state.h |  1 +
 2 files changed, 19 insertions(+)

diff --git a/block/export/export.c b/block/export/export.c
index 28a91c9c42..016943860c 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -368,3 +368,21 @@ BlockExportInfoList *qmp_query_block_exports(Error **errp)
 
     return head;
 }
+
+BlockBackend *blk_by_export_id(const char *id, Error **errp)
+{
+    BlockExport *exp;
+
+    exp = blk_exp_find(id);
+    if (exp == NULL) {
+        error_setg(errp, "Export '%s' not found", id);
+        return NULL;
+    }
+
+    if (!exp->blk) {
+        error_setg(errp, "Export '%s' is empty", id);
+        return NULL;
+    }
+
+    return exp->blk;
+}
diff --git a/include/sysemu/block-backend-global-state.h 
b/include/sysemu/block-backend-global-state.h
index 5db83ed8cb..b9dc81c34d 100644
--- a/include/sysemu/block-backend-global-state.h
+++ b/include/sysemu/block-backend-global-state.h
@@ -71,6 +71,7 @@ void blk_detach_dev(BlockBackend *blk, DeviceState *dev);
 DeviceState *blk_get_attached_dev(BlockBackend *blk);
 BlockBackend *blk_by_dev(void *dev);
 BlockBackend *blk_by_qdev_id(const char *id, Error **errp);
+BlockBackend *blk_by_export_id(const char *id, Error **errp);
 void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops, void *opaque);
 
 void blk_activate(BlockBackend *blk, Error **errp);
-- 
2.34.1