3 files changed, 38 insertions, 3 deletions

diff --git a/include/block/block.h b/include/block/block.h
index 59be83f..faee3aa 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -162,6 +162,25 @@ typedef struct BDRVReopenState {
     void *opaque;
 } BDRVReopenState;
 
+/*
+ * Block operation types
+ */
+typedef enum BlockOpType {
+    BLOCK_OP_TYPE_BACKUP_SOURCE,
+    BLOCK_OP_TYPE_BACKUP_TARGET,
+    BLOCK_OP_TYPE_CHANGE,
+    BLOCK_OP_TYPE_COMMIT,
+    BLOCK_OP_TYPE_DATAPLANE,
+    BLOCK_OP_TYPE_DRIVE_DEL,
+    BLOCK_OP_TYPE_EJECT,
+    BLOCK_OP_TYPE_EXTERNAL_SNAPSHOT,
+    BLOCK_OP_TYPE_INTERNAL_SNAPSHOT,
+    BLOCK_OP_TYPE_INTERNAL_SNAPSHOT_DELETE,
+    BLOCK_OP_TYPE_MIRROR,
+    BLOCK_OP_TYPE_RESIZE,
+    BLOCK_OP_TYPE_STREAM,
+    BLOCK_OP_TYPE_MAX,
+} BlockOpType;
 
 void bdrv_iostatus_enable(BlockDriverState *bs);
 void bdrv_iostatus_reset(BlockDriverState *bs);
@@ -197,6 +216,7 @@ int bdrv_parse_discard_flags(const char *mode, int *flags);
 int bdrv_open_image(BlockDriverState **pbs, const char *filename,
                     QDict *options, const char *bdref_key, int flags,
                     bool allow_none, Error **errp);
+void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd);
 int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp);
 void bdrv_append_temp_snapshot(BlockDriverState *bs, int flags, Error **errp);
 int bdrv_open(BlockDriverState **pbs, const char *filename,
@@ -453,8 +473,13 @@ void bdrv_disable_copy_on_read(BlockDriverState *bs);
 
 void bdrv_ref(BlockDriverState *bs);
 void bdrv_unref(BlockDriverState *bs);
-void bdrv_set_in_use(BlockDriverState *bs, int in_use);
-int bdrv_in_use(BlockDriverState *bs);
+
+bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp);
+void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason);
+void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason);
+void bdrv_op_block_all(BlockDriverState *bs, Error *reason);
+void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason);
+bool bdrv_op_blocker_is_empty(BlockDriverState *bs);
 
 #ifdef CONFIG_LINUX_AIO
 int raw_get_aio_fd(BlockDriverState *bs);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index b8cc926..f2e753f 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -270,6 +270,8 @@ typedef struct BlockLimits {
     size_t opt_mem_alignment;
 } BlockLimits;
 
+typedef struct BdrvOpBlocker BdrvOpBlocker;
+
 /*
  * Note: the function bdrv_append() copies and swaps contents of
  * BlockDriverStates, so if you add new fields to this struct, please
@@ -356,15 +358,20 @@ struct BlockDriverState {
     QTAILQ_ENTRY(BlockDriverState) device_list;
     QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps;
     int refcnt;
-    int in_use; /* users other than guest access, eg. block migration */
 
     QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;
 
+    /* operation blockers */
+    QLIST_HEAD(, BdrvOpBlocker) op_blockers[BLOCK_OP_TYPE_MAX];
+
     /* long-running background operation */
     BlockJob *job;
 
     QDict *options;
     BlockdevDetectZeroesOptions detect_zeroes;
+
+    /* The error object in use for blocking operations on backing_hd */
+    Error *backing_blocker;
 };
 
 int get_tmp_filename(char *filename, int size);
diff --git a/include/block/blockjob.h b/include/block/blockjob.h
index d76de62..c0a7875 100644
--- a/include/block/blockjob.h
+++ b/include/block/blockjob.h
@@ -106,6 +106,9 @@ struct BlockJob {
     /** The completion function that will be called when the job completes.  */
     BlockDriverCompletionFunc *cb;
 
+    /** Block other operations when block job is running */
+    Error *blocker;
+
     /** The opaque value that is passed to the completion function.  */
     void *opaque;
 };