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Re: [Qemu-block] [Qemu-devel] [PATCH v1 3/6] qemu-img: add support for -
From: |
Fam Zheng |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH v1 3/6] qemu-img: add support for -n arg to dd command |
Date: |
Thu, 26 Jan 2017 20:35:30 +0800 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
On Thu, 01/26 11:04, Daniel P. Berrange wrote:
> The -n arg to the convert command allows use of a pre-existing image,
> rather than creating a new image. This adds a -n arg to the dd command
> to get feature parity.
I remember there was a discussion about changing qemu-img dd's default to a
"conv=nocreat" semantic, if so, "-n" might not be that useful. But that part
hasn't made it into the tree, and I'm not sure which direction we should take.
(Personally I think default to nocreat is a good idea).
Fam
>
> Signed-off-by: Daniel P. Berrange <address@hidden>
> ---
> qemu-img-cmds.hx | 4 +--
> qemu-img.c | 79
> ++++++++++++++++++++++++++++++++++++--------------------
> qemu-img.texi | 7 ++++-
> 3 files changed, 59 insertions(+), 31 deletions(-)
>
> diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
> index f054599..6732713 100644
> --- a/qemu-img-cmds.hx
> +++ b/qemu-img-cmds.hx
> @@ -46,9 +46,9 @@ STEXI
> ETEXI
>
> DEF("dd", img_dd,
> - "dd [--image-opts] [-f fmt] [-O output_fmt] [bs=block_size]
> [count=blocks] [skip=blocks] if=input of=output")
> + "dd [--image-opts] [-n] [-f fmt] [-O output_fmt] [bs=block_size]
> [count=blocks] [skip=blocks] if=input of=output")
> STEXI
> address@hidden dd [--image-opts] [-f @var{fmt}] [-O @var{output_fmt}]
> address@hidden address@hidden address@hidden address@hidden address@hidden
> address@hidden dd [--image-opts] [-n] [-f @var{fmt}] [-O @var{output_fmt}]
> address@hidden address@hidden address@hidden address@hidden address@hidden
> ETEXI
>
> DEF("info", img_info,
> diff --git a/qemu-img.c b/qemu-img.c
> index 629f9e9..4d8d041 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -3917,10 +3917,10 @@ static int img_dd(int argc, char **argv)
> QemuOptsList *create_opts = NULL;
> Error *local_err = NULL;
> bool image_opts = false;
> - int c, i;
> + int c, i, skip_create = 0;
> const char *out_fmt = "raw";
> const char *fmt = NULL;
> - int64_t size = 0;
> + int64_t size = 0, out_size;
> int64_t block_count = 0, out_pos, in_pos;
> struct DdInfo dd = {
> .flags = 0,
> @@ -3954,7 +3954,7 @@ static int img_dd(int argc, char **argv)
> { 0, 0, 0, 0 }
> };
>
> - while ((c = getopt_long(argc, argv, "hf:O:", long_options, NULL))) {
> + while ((c = getopt_long(argc, argv, "hnf:O:", long_options, NULL))) {
> if (c == EOF) {
> break;
> }
> @@ -3965,6 +3965,9 @@ static int img_dd(int argc, char **argv)
> case 'f':
> fmt = optarg;
> break;
> + case 'n':
> + skip_create = 1;
> + break;
> case '?':
> error_report("Try 'qemu-img --help' for more information.");
> ret = -1;
> @@ -4051,22 +4054,25 @@ static int img_dd(int argc, char **argv)
> ret = -1;
> goto out;
> }
> - if (!drv->create_opts) {
> - error_report("Format driver '%s' does not support image creation",
> - drv->format_name);
> - ret = -1;
> - goto out;
> - }
> - if (!proto_drv->create_opts) {
> - error_report("Protocol driver '%s' does not support image creation",
> - proto_drv->format_name);
> - ret = -1;
> - goto out;
> - }
> - create_opts = qemu_opts_append(create_opts, drv->create_opts);
> - create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
>
> - opts = qemu_opts_create(create_opts, NULL, 0, &error_abort);
> + if (!skip_create) {
> + if (!drv->create_opts) {
> + error_report("Format driver '%s' does not support image
> creation",
> + drv->format_name);
> + ret = -1;
> + goto out;
> + }
> + if (!proto_drv->create_opts) {
> + error_report("Protocol driver '%s' does not support image
> creation",
> + proto_drv->format_name);
> + ret = -1;
> + goto out;
> + }
> + create_opts = qemu_opts_append(create_opts, drv->create_opts);
> + create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
> +
> + opts = qemu_opts_create(create_opts, NULL, 0, &error_abort);
> + }
>
> size = blk_getlength(blk1);
> if (size < 0) {
> @@ -4083,19 +4089,22 @@ static int img_dd(int argc, char **argv)
> /* Overflow means the specified offset is beyond input image's size */
> if (dd.flags & C_SKIP && (in.offset > INT64_MAX / in.bsz ||
> size < in.bsz * in.offset)) {
> - qemu_opt_set_number(opts, BLOCK_OPT_SIZE, 0, &error_abort);
> + out_size = 0;
> } else {
> - qemu_opt_set_number(opts, BLOCK_OPT_SIZE,
> - size - in.bsz * in.offset, &error_abort);
> + out_size = size - in.bsz * in.offset;
> }
>
> - ret = bdrv_create(drv, out.filename, opts, &local_err);
> - if (ret < 0) {
> - error_reportf_err(local_err,
> - "%s: error while creating output image: ",
> - out.filename);
> - ret = -1;
> - goto out;
> + if (!skip_create) {
> + qemu_opt_set_number(opts, BLOCK_OPT_SIZE, out_size, &error_abort);
> +
> + ret = bdrv_create(drv, out.filename, opts, &local_err);
> + if (ret < 0) {
> + error_reportf_err(local_err,
> + "%s: error while creating output image: ",
> + out.filename);
> + ret = -1;
> + goto out;
> + }
> }
>
> /* TODO, we can't honour --image-opts for the target,
> @@ -4111,6 +4120,20 @@ static int img_dd(int argc, char **argv)
> goto out;
> }
>
> + if (skip_create) {
> + int64_t existing_size = blk_getlength(blk2);
> + if (existing_size < 0) {
> + error_report("unable to get output image length: %s",
> + strerror(-existing_size));
> + ret = -1;
> + goto out;
> + } else if (existing_size < out_size) {
> + error_report("output file is smaller than input data length");
> + ret = -1;
> + goto out;
> + }
> + }
> +
> if (dd.flags & C_SKIP && (in.offset > INT64_MAX / in.bsz ||
> size < in.offset * in.bsz)) {
> /* We give a warning if the skip option is bigger than the input
> diff --git a/qemu-img.texi b/qemu-img.texi
> index 174aae3..b952d6a 100644
> --- a/qemu-img.texi
> +++ b/qemu-img.texi
> @@ -326,7 +326,7 @@ skipped. This is useful for formats such as @code{rbd} if
> the target
> volume has already been created with site specific options that cannot
> be supplied through qemu-img.
>
> address@hidden dd [-f @var{fmt}] [-O @var{output_fmt}] address@hidden
> address@hidden address@hidden address@hidden address@hidden
> address@hidden dd [-n] [-f @var{fmt}] [-O @var{output_fmt}] address@hidden
> address@hidden address@hidden address@hidden address@hidden
>
> Dd copies from @var{input} file to @var{output} file converting it from
> @var{fmt} format to @var{output_fmt} format.
> @@ -337,6 +337,11 @@ dd will stop reading input after reading @var{blocks}
> input blocks.
>
> The size syntax is similar to dd(1)'s size syntax.
>
> +If the @code{-n} option is specified, the target volume creation will be
> +skipped. This is useful for formats such as @code{rbd} if the target
> +volume has already been created with site specific options that cannot
> +be supplied through qemu-img.
> +
> @item info [-f @var{fmt}] address@hidden [--backing-chain] @var{filename}
>
> Give information about the disk image @var{filename}. Use it in
> --
> 2.9.3
>
>