if a destination has has_zero_init = 0, but it supports
discard zeroes use discard to convert the target
into an all zero device.
Signed-off-by: Peter Lieven <p...@kamp.de>
---
qemu-img.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 55 insertions(+), 1 deletion(-)
diff --git a/qemu-img.c b/qemu-img.c
index f8c97d3..cbde02f 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1342,7 +1342,8 @@ static int img_convert(int argc, char **argv)
goto out;
}
- flags = BDRV_O_RDWR;
+ flags = BDRV_O_RDWR | BDRV_O_UNMAP;
+
ret = bdrv_parse_cache_flags(cache, &flags);
if (ret < 0) {
error_report("Invalid cache option: %s", cache);
@@ -1442,8 +1443,61 @@ static int img_convert(int argc, char **argv)
/* signal EOF to align */
bdrv_write_compressed(out_bs, 0, NULL, 0);
} else {
+ BlockDriverInfo bdi;
+
int has_zero_init = bdrv_has_zero_init(out_bs);
+ /* if the target has no zero init by default check if we
+ * can discard blocks to zeroize the device */
+ if (!has_zero_init && !out_baseimg &&
+ bdrv_get_info(out_bs, &bdi) == 0 &&
+ bdi.discard_zeroes && bdi.max_unmap > 0) {
+ int64_t target_size = bdrv_getlength(out_bs) / BDRV_SECTOR_SIZE;
+ int64_t sector_num2 = -1;
+ int n;
+ sector_num = 0;
+ for (;;) {
+ nb_sectors = target_size - sector_num;
+ if (nb_sectors <= 0) {
+ has_zero_init = 1;
+ break;
+ }
+ if (nb_sectors > INT_MAX) {
+ nb_sectors = INT_MAX;
+ }
+ if (!bdrv_is_allocated(out_bs, sector_num, nb_sectors, &n)) {
+ if (!n) {
+ /* an error occured, continue with has_zero_init = 0 */
+ break;
+ }
+ sector_num += n;
+ continue;
+ }
+ if (sector_num == sector_num2) {
+ /* some drivers allow a discard to silently fail.
+ * double-check that we do not try to discard the
+ * same sectors twice. if thats the case
+ * continue with has_zero_init = 0 */
+ break;
+ }
+ sector_num2 = sector_num;
+ while (n > 0) {
+ nb_sectors = n;
+ if (nb_sectors > bdi.max_unmap) {
+ nb_sectors = bdi.max_unmap;
+ }
+ ret = bdrv_discard(out_bs, sector_num2, nb_sectors);
+ if (ret < 0) {
+ error_report("error while discarding at sector %"
PRId64 ": %s",
+ sector_num, strerror(-ret));
+ goto out;
+ }
+ sector_num2 += nb_sectors;
+ n -= nb_sectors;;
+ }
+ }
+ }
+
sector_num = 0; // total number of sectors converted so far
nb_sectors = total_sectors - sector_num;
if (nb_sectors != 0) {
--
1.7.9.5
