diff options
| -rw-r--r-- | qemu-img.c | 10 | ||||
| -rw-r--r-- | qemu-img.texi | 6 |
2 files changed, 13 insertions, 3 deletions
diff --git a/qemu-img.c b/qemu-img.c index b6b5644cb6..cc3fed7b44 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -100,8 +100,12 @@ static void help(void) " '-h' with or without a command shows this help and lists the supported formats\n" " '-p' show progress of command (only certain commands)\n" " '-q' use Quiet mode - do not print any output (except errors)\n" - " '-S' indicates the consecutive number of bytes that must contain only zeros\n" - " for qemu-img to create a sparse image during conversion\n" + " '-S' indicates the consecutive number of bytes (defaults to 4k) that must\n" + " contain only zeros for qemu-img to create a sparse image during\n" + " conversion. If the number of bytes is 0, the source will not be scanned for\n" + " unallocated or zero sectors, and the destination image will always be\n" + " fully allocated\n" + " images will always be fully allocated\n" " '--output' takes the format in which the output must be done (human or json)\n" " '-n' skips the target volume creation (useful if the volume is created\n" " prior to running qemu-img)\n" @@ -1465,7 +1469,7 @@ static int img_convert(int argc, char **argv) /* signal EOF to align */ bdrv_write_compressed(out_bs, 0, NULL, 0); } else { - int has_zero_init = bdrv_has_zero_init(out_bs); + int has_zero_init = min_sparse ? bdrv_has_zero_init(out_bs) : 0; sector_num = 0; // total number of sectors converted so far nb_sectors = total_sectors - sector_num; diff --git a/qemu-img.texi b/qemu-img.texi index 768054e900..da36975d70 100644 --- a/qemu-img.texi +++ b/qemu-img.texi @@ -193,6 +193,12 @@ Image conversion is also useful to get smaller image when using a growable format such as @code{qcow} or @code{cow}: the empty sectors are detected and suppressed from the destination image. +@var{sparse_size} indicates the consecutive number of bytes (defaults to 4k) +that must contain only zeros for qemu-img to create a sparse image during +conversion. If @var{sparse_size} is 0, the source will not be scanned for +unallocated or zero sectors, and the destination image will always be +fully allocated. + You can use the @var{backing_file} option to force the output image to be created as a copy on write image of the specified base image; the @var{backing_file} should have the same content as the input's base image, |