On Fri, 2019-07-12 at 19:35 +0200, Max Reitz wrote:
> If a protocol driver does not support image creation, we can see whether
> maybe the file exists already. If so, just truncating it will be
> sufficient.
>
> Signed-off-by: Max Reitz <mre...@redhat.com>
> ---
> block.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++---------
> 1 file changed, 71 insertions(+), 12 deletions(-)
>
> diff --git a/block.c b/block.c
> index c139540f2b..5466585501 100644
> --- a/block.c
> +++ b/block.c
> @@ -531,20 +531,63 @@ out:
> return ret;
> }
>
> -int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp)
> +static int bdrv_create_file_fallback(const char *filename, BlockDriver *drv,
> + QemuOpts *opts, Error **errp)
> {
> - BlockDriver *drv;
> + BlockBackend *blk;
> + QDict *options = qdict_new();
> + int64_t size = 0;
> + char *buf = NULL;
> + PreallocMode prealloc;
> Error *local_err = NULL;
> int ret;
>
> + size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
> + buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
> + prealloc = qapi_enum_parse(&PreallocMode_lookup, buf,
> + PREALLOC_MODE_OFF, &local_err);
> + g_free(buf);
> + if (local_err) {
> + error_propagate(errp, local_err);
> + return -EINVAL;
> + }
> +
> + if (prealloc != PREALLOC_MODE_OFF) {
> + error_setg(errp, "Unsupported preallocation mode '%s'",
> + PreallocMode_str(prealloc));
> + return -ENOTSUP;
> + }
> +
> + qdict_put_str(options, "driver", drv->format_name);
> +
> + blk = blk_new_open(filename, NULL, options,
> + BDRV_O_RDWR | BDRV_O_RESIZE, errp);
> + if (!blk) {
> + error_prepend(errp, "Protocol driver '%s' does not support image "
> + "creation, and opening the image failed: ",
> + drv->format_name);
> + return -EINVAL;
> + }
> +
> + ret = blk_truncate_for_formatting(blk, size, errp);
> + blk_unref(blk);
> + return ret;
> +}
> +
> +int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp)
> +{
> + BlockDriver *drv;
> +
> drv = bdrv_find_protocol(filename, true, errp);
> if (drv == NULL) {
> return -ENOENT;
> }
>
> - ret = bdrv_create(drv, filename, opts, &local_err);
> - error_propagate(errp, local_err);
> - return ret;
> + if (drv->bdrv_co_create_opts) {
> + return bdrv_create(drv, filename, opts, errp);
> + } else {
> + return bdrv_create_file_fallback(filename, drv, opts, errp);
> + }
> }
>
> /**
> @@ -1420,6 +1463,24 @@ QemuOptsList bdrv_runtime_opts = {
> },
> };
>
> +static QemuOptsList fallback_create_opts = {
> + .name = "fallback-create-opts",
> + .head = QTAILQ_HEAD_INITIALIZER(fallback_create_opts.head),
> + .desc = {
> + {
> + .name = BLOCK_OPT_SIZE,
> + .type = QEMU_OPT_SIZE,
> + .help = "Virtual disk size"
> + },
> + {
> + .name = BLOCK_OPT_PREALLOC,
> + .type = QEMU_OPT_STRING,
> + .help = "Preallocation mode (allowed values: off)"
> + },
> + { /* end of list */ }
> + }
> +};
> +
> /*
> * Common part for opening disk images and files
> *
> @@ -5681,14 +5742,12 @@ void bdrv_img_create(const char *filename, const char
> *fmt,
> return;
> }
>
> - if (!proto_drv->create_opts) {
> - error_setg(errp, "Protocol driver '%s' does not support image
> creation",
> - proto_drv->format_name);
> - return;
> - }
> -
> create_opts = qemu_opts_append(create_opts, drv->create_opts);
> - create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
> + if (proto_drv->create_opts) {
> + create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
> + } else {
> + create_opts = qemu_opts_append(create_opts, &fallback_create_opts);
> + }
>
> /* Create parameter list with default values */
> opts = qemu_opts_create(create_opts, NULL, 0, &error_abort);
Looks good!
Reviewed-by: Maxim Levitsky <mlevi...@redhat.com>
Best regards,
Maxim Levitsky
