[PATCH v4 2/7] vmdk: Add trivial backing_fmt support

vmdk already requires that if backing_file is present, that it be another vmdk image (see vmdk_co_do_create). Meanwhile, we want to move towards always being explicit about the backing format for other drivers where it matters. So for convenience, make qemu-img create -F vmdk work, while rejecting all other explicit formats (note that this is only for QemuOpts usage; there is no change to the QAPI to allow a format through -blockdev). Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- block/vmdk.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/block/vmdk.c b/block/vmdk.c index 20e909d99794..3c7893817afe 100644 --- a/block/vmdk.c +++ b/block/vmdk.c @@ -2611,6 +2611,14 @@ static int coroutine_fn vmdk_co_create_opts(const char *filename, QemuOpts *opts bool zeroed_grain; bool compat6; VMDKCreateOptsData data; + char *backing_fmt = NULL; + + backing_fmt = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FMT); + if (backing_fmt && strcmp(backing_fmt, "vmdk") != 0) { + error_setg(errp, "backing_file must be a vmdk image"); + ret = -EINVAL; + goto exit; + } if (filename_decompose(filename, path, prefix, postfix, PATH_MAX, errp)) { ret = -EINVAL; @@ -2669,6 +2677,7 @@ static int coroutine_fn vmdk_co_create_opts(const char *filename, QemuOpts *opts vmdk_co_create_opts_cb, &data, errp); exit: + g_free(backing_fmt); g_free(adapter_type); g_free(backing_file); g_free(hw_version); @@ -3005,6 +3014,11 @@ static QemuOptsList vmdk_create_opts = { .type = QEMU_OPT_STRING, .help = "File name of a base image" }, + { + .name = BLOCK_OPT_BACKING_FMT, + .type = QEMU_OPT_STRING, + .help = "Must be 'vmdk' if present", + }, { .name = BLOCK_OPT_COMPAT6, .type = QEMU_OPT_BOOL, -- 2.25.1