2 files changed, 18 insertions, 0 deletions
diff --git a/include/block/block.h b/include/block/block.h
index c9d7c58765..5b81e33e94 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -143,6 +143,16 @@ typedef struct HDGeometry {
 #define BDRV_REQUEST_MAX_BYTES (BDRV_REQUEST_MAX_SECTORS << BDRV_SECTOR_BITS)
 
 /*
+ * We want allow aligning requests and disk length up to any 32bit alignment
+ * and don't afraid of overflow.
+ * To achieve it, and in the same time use some pretty number as maximum disk
+ * size, let's define maximum "length" (a limit for any offset/bytes request and
+ * for disk size) to be the greatest power of 2 less than INT64_MAX.
+ */
+#define BDRV_MAX_ALIGNMENT (1L << 30)
+#define BDRV_MAX_LENGTH (QEMU_ALIGN_DOWN(INT64_MAX, BDRV_MAX_ALIGNMENT))
+
+/*
  * Allocation status flags for bdrv_block_status() and friends.
  *
  * Public flags:
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 95d9333be1..1eeafc118c 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -70,6 +70,12 @@ enum BdrvTrackedRequestType {
     BDRV_TRACKED_TRUNCATE,
 };
 
+/*
+ * That is not quite good that BdrvTrackedRequest structure is public,
+ * as block/io.c is very careful about incoming offset/bytes being
+ * correct. Be sure to assert bdrv_check_request() succeeded after any
+ * modification of BdrvTrackedRequest object out of block/io.c
+ */
 typedef struct BdrvTrackedRequest {
     BlockDriverState *bs;
     int64_t offset;
@@ -87,6 +93,8 @@ typedef struct BdrvTrackedRequest {
     struct BdrvTrackedRequest *waiting_for;
 } BdrvTrackedRequest;
 
+int bdrv_check_request(int64_t offset, int64_t bytes);
+
 struct BlockDriver {
     const char *format_name;
     int instance_size;