diff options
| -rw-r--r-- | block/mirror.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/block/mirror.c b/block/mirror.c index 724318f037..c2c5099c95 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -920,11 +920,16 @@ static int coroutine_fn GRAPH_UNLOCKED mirror_dirty_init(MirrorBlockJob *s) * zeroing happened externally (ret > 0) or if we have a fast * way to pre-zero the image (the dirty bitmap will be * populated later by the non-zero portions, the same as for - * TOP mode). If pre-zeroing is not fast, then our only - * recourse is to mark the entire image dirty. The act of - * pre-zeroing will populate the zero bitmap. + * TOP mode). If pre-zeroing is not fast, or we need to visit + * the entire image in order to punch holes even in the + * non-allocated regions of the source, then just mark the + * entire image dirty and leave the zero bitmap clear at this + * point in time. Otherwise, it can be faster to pre-zero the + * image now, even if we re-write the allocated portions of + * the disk later, and the pre-zero pass will populate the + * zero bitmap. */ - if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { + if (!bdrv_can_write_zeroes_with_unmap(target_bs) || punch_holes) { bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length); return 0; } |