Commit 11212d8f authored Sep 04, 2013 by Paolo Bonzini Committed by Stefan Hajnoczi Sep 06, 2013

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 <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

parent e4a86f88

block.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -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);
		}

qemu-img.c

+1 −8

Original line number	Diff line number	Diff line
		@@ -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) {