diff options
Diffstat (limited to 'qemu-img.c')
| -rw-r--r-- | qemu-img.c | 34 |
1 files changed, 19 insertions, 15 deletions
diff --git a/qemu-img.c b/qemu-img.c index ab380c8a44..913ad34bf8 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -493,7 +493,7 @@ static int img_convert(int argc, char **argv) ret = bdrv_create(drv, out_filename, total_sectors, out_baseimg, flags); if (ret < 0) { if (ret == -ENOTSUP) { - error("Formatting not supported for file format '%s'", fmt); + error("Formatting not supported for file format '%s'", out_fmt); } else { error("Error while formatting '%s'", out_filename); } @@ -592,18 +592,17 @@ static int img_convert(int argc, char **argv) if (n > bs_offset + bs_sectors - sector_num) n = bs_offset + bs_sectors - sector_num; - /* If the output image is being created as a copy on write image, - assume that sectors which are unallocated in the input image - are present in both the output's and input's base images (no - need to copy them). */ - if (out_baseimg) { - if (!bdrv_is_allocated(bs[bs_i], sector_num - bs_offset, n, &n1)) { - sector_num += n1; - continue; - } - /* The next 'n1' sectors are allocated in the input image. Copy - only those as they may be followed by unallocated sectors. */ - n = n1; + if (drv != &bdrv_host_device) { + if (!bdrv_is_allocated(bs[bs_i], sector_num - bs_offset, + n, &n1)) { + sector_num += n1; + continue; + } + /* The next 'n1' sectors are allocated in the input image. Copy + only those as they may be followed by unallocated sectors. */ + n = n1; + } else { + n1 = n; } if (bdrv_read(bs[bs_i], sector_num - bs_offset, buf, n) < 0) @@ -615,8 +614,13 @@ static int img_convert(int argc, char **argv) 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 (out_baseimg || is_allocated_sectors(buf1, n, &n1)) { + 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 (drv == &bdrv_host_device || out_baseimg || + is_allocated_sectors(buf1, n, &n1)) { if (bdrv_write(out_bs, sector_num, buf1, n1) < 0) error("error while writing"); } |