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authorPaolo Bonzini <pbonzini@redhat.com>2013-09-04 19:00:27 +0200
committerStefan Hajnoczi <stefanha@redhat.com>2013-09-06 15:25:09 +0200
commit11212d8fa08a4e5bd56bb4f6877f9a4c0439a02b (patch)
tree3b8b6048ac67fe76fdc1b279a66e403c3f91098b
parente4a86f88cc6b214c37b4abe9160e41f0338ce4cd (diff)
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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>
-rw-r--r--block.c5
-rw-r--r--qemu-img.c9
2 files changed, 6 insertions, 8 deletions
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) {