diff options
Diffstat (limited to 'qemu-img.c')
| -rw-r--r-- | qemu-img.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/qemu-img.c b/qemu-img.c index b6b5644cb6..dc0c2f0ed3 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" @@ -1351,7 +1355,7 @@ static int img_convert(int argc, char **argv) } } - flags = BDRV_O_RDWR; + flags = min_sparse ? (BDRV_O_RDWR | BDRV_O_UNMAP) : BDRV_O_RDWR; ret = bdrv_parse_cache_flags(cache, &flags); if (ret < 0) { error_report("Invalid cache option: %s", cache); @@ -1465,7 +1469,15 @@ 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; + + if (!has_zero_init && bdrv_can_write_zeroes_with_unmap(out_bs)) { + ret = bdrv_make_zero(out_bs, BDRV_REQ_MAY_UNMAP); + if (ret < 0) { + goto out; + } + has_zero_init = 1; + } sector_num = 0; // total number of sectors converted so far nb_sectors = total_sectors - sector_num; |