From 4d7c487eac1652dfe4498fe84f32900ad461d61b Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Wed, 24 Jul 2019 19:12:29 +0200 Subject: [PATCH] qemu-img: Fix bdrv_has_zero_init() use in convert bdrv_has_zero_init() only has meaning for newly created images or image areas. If qemu-img convert did not create the image itself, it cannot rely on bdrv_has_zero_init()'s result to carry any meaning. Signed-off-by: Max Reitz Message-id: 20190724171239.8764-2-mreitz@redhat.com Reviewed-by: Maxim Levitsky Reviewed-by: Stefano Garzarella Signed-off-by: Max Reitz --- qemu-img.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/qemu-img.c b/qemu-img.c index c920e3564c..7daa05e51a 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -1578,6 +1578,7 @@ typedef struct ImgConvertState { bool has_zero_init; bool compressed; bool unallocated_blocks_are_zero; + bool target_is_new; bool target_has_backing; int64_t target_backing_sectors; /* negative if unknown */ bool wr_in_order; @@ -1975,9 +1976,11 @@ static int convert_do_copy(ImgConvertState *s) int64_t sector_num = 0; /* Check whether we have zero initialisation or can get it efficiently */ - s->has_zero_init = s->min_sparse && !s->target_has_backing - ? bdrv_has_zero_init(blk_bs(s->target)) - : false; + if (s->target_is_new && s->min_sparse && !s->target_has_backing) { + s->has_zero_init = bdrv_has_zero_init(blk_bs(s->target)); + } else { + s->has_zero_init = false; + } if (!s->has_zero_init && !s->target_has_backing && bdrv_can_write_zeroes_with_unmap(blk_bs(s->target))) @@ -2428,6 +2431,8 @@ static int img_convert(int argc, char **argv) } } + s.target_is_new = !skip_create; + flags = s.min_sparse ? (BDRV_O_RDWR | BDRV_O_UNMAP) : BDRV_O_RDWR; ret = bdrv_parse_cache_mode(cache, &flags, &writethrough); if (ret < 0) {