@@ -2240,6 +2240,43 @@ BlockDriverAIOCB *bdrv_aio_writev(BlockDriverState *bs, int64_t sector_num,
return ret;
}
+/**
+ * Attempt to copy unallocated sectors from backing file.
+ *
+ * @sector_num - the first sector to start from
+ * @cb - completion callback
+ * @opaque - data to pass completion callback
+ *
+ * Returns NULL if the image format not support the operation, the image is
+ * read-only, or no image is open.
+ *
+ * The intention of this function is for a user to execute it once with a
+ * sector_num of 0 and then upon receiving a completion callback, to remember
+ * the number of sectors copied, and then to call this function again with
+ * an offset adjusted by the number of sectors previously copied.
+ *
+ * This allows a user to progressive stream in an image at a pace that makes
+ * sense. In general, this function tries to do the smallest amount of I/O
+ * possible to do some useful work.
+ *
+ * This function only really makes sense in combination with a block format
+ * that supports copy on read and has it enabled. If copy on read is not
+ * enabled, a block format driver may return NULL.
+ *
+ * If an I/O error occurs the completion callback is invoked with -errno in the
+ * nb_sectors argument.
+ */
+BlockDriverAIOCB *bdrv_aio_copy_backing(BlockDriverState *bs,
+ int64_t sector_num,
+ BlockDriverCopyBackingCB *cb,
+ void *opaque)
+{
+ if (!bs->drv || bs->read_only || !bs->drv->bdrv_aio_copy_backing) {
+ return NULL;
+ }
+
+ return bs->drv->bdrv_aio_copy_backing(bs, sector_num, cb, opaque);
+}
typedef struct MultiwriteCB {
int error;
@@ -113,6 +113,7 @@ typedef struct BlockDriverAIOCB BlockDriverAIOCB;
typedef void BlockDriverCompletionFunc(void *opaque, int ret);
typedef void BlockDriverDirtyHandler(BlockDriverState *bs, int64_t sector,
int sector_num);
+typedef void BlockDriverCopyBackingCB(void *opaque, int nb_sectors);
BlockDriverAIOCB *bdrv_aio_readv(BlockDriverState *bs, int64_t sector_num,
QEMUIOVector *iov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque);
@@ -121,6 +122,10 @@ BlockDriverAIOCB *bdrv_aio_writev(BlockDriverState *bs, int64_t sector_num,
BlockDriverCompletionFunc *cb, void *opaque);
BlockDriverAIOCB *bdrv_aio_flush(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque);
+BlockDriverAIOCB *bdrv_aio_copy_backing(BlockDriverState *bs,
+ int64_t sector_num,
+ BlockDriverCopyBackingCB *cb,
+ void *opaque);
void bdrv_aio_cancel(BlockDriverAIOCB *acb);
typedef struct BlockRequest {
@@ -74,6 +74,8 @@ struct BlockDriver {
BlockDriverCompletionFunc *cb, void *opaque);
BlockDriverAIOCB *(*bdrv_aio_flush)(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque);
+ BlockDriverAIOCB *(*bdrv_aio_copy_backing)(BlockDriverState *bs,
+ int64_t sector_num, BlockDriverCopyBackingCB *cb, void *opaque);
int (*bdrv_discard)(BlockDriverState *bs, int64_t sector_num,
int nb_sectors);