diff options
| -rw-r--r-- | qemu-img.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/qemu-img.c b/qemu-img.c index 491a460ecf..47923663be 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -1475,10 +1475,21 @@ static int convert_iteration_sectors(ImgConvertState *s, int64_t sector_num) } else if (!s->target_has_backing) { /* Without a target backing file we must copy over the contents of * the backing file as well. */ - /* TODO Check block status of the backing file chain to avoid + /* Check block status of the backing file chain to avoid * needlessly reading zeroes and limiting the iteration to the * buffer size */ - s->status = BLK_DATA; + ret = bdrv_get_block_status_above(blk_bs(s->src[s->src_cur]), NULL, + sector_num - s->src_cur_offset, + n, &n, &file); + if (ret < 0) { + return ret; + } + + if (ret & BDRV_BLOCK_ZERO) { + s->status = BLK_ZERO; + } else { + s->status = BLK_DATA; + } } else { s->status = BLK_BACKING_FILE; } |