From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40680) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VHy9L-0005fP-Sw for qemu-devel@nongnu.org; Fri, 06 Sep 2013 11:40:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VHy9F-0005dG-T4 for qemu-devel@nongnu.org; Fri, 06 Sep 2013 11:40:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33585) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VHy9F-0005d9-Ke for qemu-devel@nongnu.org; Fri, 06 Sep 2013 11:40:37 -0400 From: Stefan Hajnoczi Date: Fri, 6 Sep 2013 17:38:58 +0200 Message-Id: <1378481953-23099-28-git-send-email-stefanha@redhat.com> In-Reply-To: <1378481953-23099-1-git-send-email-stefanha@redhat.com> References: <1378481953-23099-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PULL 27/42] qemu-img: always probe the input image for allocated sectors List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Paolo Bonzini , Stefan Hajnoczi , Anthony Liguori From: Paolo Bonzini qemu-img convert can assume "that sectors which are unallocated in the input image are present in both the output's and input's base images". However it is only doing this if the output image returns true for bdrv_has_zero_init(). Testing bdrv_has_zero_init() does not make much sense if the output image is copy-on-write, because a copy-on-write image is never initialized to zero (it is initialized to the content of the backing file). There is nothing here that makes has_zero_init images special. The input and output must be equal for the operation to make sense, and that's it. Reviewed-by: Eric Blake Signed-off-by: Paolo Bonzini Signed-off-by: Stefan Hajnoczi --- qemu-img.c | 40 +++++++++++++++++++--------------------- 1 file changed, 19 insertions(+), 21 deletions(-) diff --git a/qemu-img.c b/qemu-img.c index 27cc006..5cc579d 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -1502,28 +1502,26 @@ static int img_convert(int argc, char **argv) n = bs_offset + bs_sectors - sector_num; } - if (has_zero_init) { - /* 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) { - ret = bdrv_is_allocated(bs[bs_i], sector_num - bs_offset, - n, &n1); - if (ret < 0) { - error_report("error while reading metadata for sector " - "%" PRId64 ": %s", - sector_num - bs_offset, strerror(-ret)); - goto out; - } - if (!ret) { - 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 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) { + ret = bdrv_is_allocated(bs[bs_i], sector_num - bs_offset, + n, &n1); + if (ret < 0) { + error_report("error while reading metadata for sector " + "%" PRId64 ": %s", + sector_num - bs_offset, strerror(-ret)); + goto out; + } + if (!ret) { + 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; } -- 1.8.3.1