From 5a37b60a61c4c334e3b194758871f41494317d42 Mon Sep 17 00:00:00 2001 From: Peter Lieven Date: Thu, 24 Oct 2013 12:07:06 +0200 Subject: qemu-img: conditionally zero out target on convert If the target has_zero_init = 0, but supports efficiently writing zeroes by unmapping we call bdrv_make_zero to avoid fully allocating the target. This currently works only for iscsi. It can be extended to raw with BLKDISCARDZEROES for example. Reviewed-by: Eric Blake Signed-off-by: Peter Lieven Signed-off-by: Stefan Hajnoczi --- qemu-img.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'qemu-img.c') diff --git a/qemu-img.c b/qemu-img.c index cc3fed7b44..dc0c2f0ed3 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -1355,7 +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); @@ -1471,6 +1471,14 @@ static int img_convert(int argc, char **argv) } else { 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; if (nb_sectors != 0) { -- cgit v1.2.1