From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53032) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XzTjc-0005w4-4p for qemu-devel@nongnu.org; Fri, 12 Dec 2014 12:10:38 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XzTjV-0004Eu-Uk for qemu-devel@nongnu.org; Fri, 12 Dec 2014 12:10:32 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45150) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XzTjV-0004Eo-Nq for qemu-devel@nongnu.org; Fri, 12 Dec 2014 12:10:25 -0500 From: Stefan Hajnoczi Date: Fri, 12 Dec 2014 17:09:53 +0000 Message-Id: <1418404205-6213-8-git-send-email-stefanha@redhat.com> In-Reply-To: <1418404205-6213-1-git-send-email-stefanha@redhat.com> References: <1418404205-6213-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PULL 07/19] block: vhdx - change .vhdx_create default block state to ZERO List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , Jeff Cody , Stefan Hajnoczi From: Jeff Cody The VHDX spec specifies that the default new block state is PAYLOAD_BLOCK_NOT_PRESENT for a dynamic VHDX image, and PAYLOAD_BLOCK_FULLY_PRESENT for a fixed VHDX image. However, in order to create space-efficient VHDX images with qemu-img convert, it is desirable to be able to set has_zero_init to true for VHDX. There is currently an option when creating VHDX images, to use block state ZERO for new blocks. However, this currently defaults to 'off'. In order to be able to eventually set has_zero_init to true for VHDX, this needs to default to 'on'. This patch changes the default to 'on', and provides some help information to warn against setting it to 'off' when using qemu-img convert. [Max Reitz pointed out that a full stop was missing at the end of the VHDX_BLOCK_OPT_ZERO option help text. I have added it. --Stefan] Signed-off-by: Jeff Cody Reviewed-by: Max Reitz Message-id: 85164899eacc86e150c3ceba793cf93b398dedd7.1418018421.git.jcody@redhat.com Signed-off-by: Stefan Hajnoczi --- block/vhdx.c | 6 ++++-- qemu-doc.texi | 6 +++++- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/block/vhdx.c b/block/vhdx.c index bec10bd..46d504c 100644 --- a/block/vhdx.c +++ b/block/vhdx.c @@ -1774,7 +1774,7 @@ static int vhdx_create(const char *filename, QemuOpts *opts, Error **errp) log_size = qemu_opt_get_size_del(opts, VHDX_BLOCK_OPT_LOG_SIZE, 0); block_size = qemu_opt_get_size_del(opts, VHDX_BLOCK_OPT_BLOCK_SIZE, 0); type = qemu_opt_get_del(opts, BLOCK_OPT_SUBFMT); - use_zero_blocks = qemu_opt_get_bool_del(opts, VHDX_BLOCK_OPT_ZERO, false); + use_zero_blocks = qemu_opt_get_bool_del(opts, VHDX_BLOCK_OPT_ZERO, true); if (image_size > VHDX_MAX_IMAGE_SIZE) { error_setg_errno(errp, EINVAL, "Image size too large; max of 64TB"); @@ -1936,7 +1936,9 @@ static QemuOptsList vhdx_create_opts = { { .name = VHDX_BLOCK_OPT_ZERO, .type = QEMU_OPT_BOOL, - .help = "Force use of payload blocks of type 'ZERO'. Non-standard." + .help = "Force use of payload blocks of type 'ZERO'. "\ + "Non-standard, but default. Do not set to 'off' when "\ + "using 'qemu-img convert' with subformat=dynamic." }, { NULL } } diff --git a/qemu-doc.texi b/qemu-doc.texi index ad418f8..aabe8df 100644 --- a/qemu-doc.texi +++ b/qemu-doc.texi @@ -698,7 +698,11 @@ Supported options: Specifies which VHDX subformat to use. Valid options are @code{dynamic} (default) and @code{fixed}. @item block_state_zero -Force use of payload blocks of type 'ZERO'. +Force use of payload blocks of type 'ZERO'. Can be set to @code{on} (default) +or @code{off}. When set to @code{off}, new blocks will be created as +@code{PAYLOAD_BLOCK_NOT_PRESENT}, which means parsers are free to return +arbitrary data for those blocks. Do not set to @code{off} when using +@code{qemu-img convert} with @code{subformat=dynamic}. @item block_size Block size; min 1 MB, max 256 MB. 0 means auto-calculate based on image size. @item log_size -- 2.1.0