From: Paolo Bonzini Date: Wed, 4 Sep 2013 17:00:27 +0000 (+0200) Subject: block: make bdrv_has_zero_init return false for copy-on-write-images X-Git-Tag: TizenStudio_2.0_p2.3.2~208^2~1362^2~14 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=11212d8fa08a4e5bd56bb4f6877f9a4c0439a02b;p=sdk%2Femulator%2Fqemu.git block: make bdrv_has_zero_init return false for copy-on-write-images This helps implementing is_allocated on top of get_block_status. Reviewed-by: Eric Blake Signed-off-by: Paolo Bonzini Signed-off-by: Stefan Hajnoczi --- diff --git a/block.c b/block.c index 5df17de..2a90893 100644 --- a/block.c +++ b/block.c @@ -3031,6 +3031,11 @@ int bdrv_has_zero_init(BlockDriverState *bs) { assert(bs->drv); + /* If BS is a copy on write image, it is initialized to + the contents of the base image, which may not be zeroes. */ + if (bs->backing_hd) { + return 0; + } if (bs->drv->bdrv_has_zero_init) { return bs->drv->bdrv_has_zero_init(bs); } diff --git a/qemu-img.c b/qemu-img.c index 5cc579d..b074fa7 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -1537,14 +1537,7 @@ static int img_convert(int argc, char **argv) should add a specific call to have the info to go faster */ buf1 = buf; while (n > 0) { - /* If the output image is being created as a copy on write image, - copy all sectors even the ones containing only NUL bytes, - because they may differ from the sectors in the base image. - - If the output is to a host device, we also write out - sectors that are entirely 0, since whatever data was - already there is garbage, not 0s. */ - if (!has_zero_init || out_baseimg || + if (!has_zero_init || is_allocated_sectors_min(buf1, n, &n1, min_sparse)) { ret = bdrv_write(out_bs, sector_num, buf1, n1); if (ret < 0) {