[PATCH v4 1/7] sheepdog: Add trivial backing_fmt support

Sheepdog already requires that if backing_file is present, that it be another sheepdog image (see sd_co_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 sheepdog 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/sheepdog.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/block/sheepdog.c b/block/sheepdog.c index cfa84338a2d6..376f4ef74638 100644 --- a/block/sheepdog.c +++ b/block/sheepdog.c @@ -2166,8 +2166,16 @@ static int coroutine_fn sd_co_create_opts(const char *filename, QemuOpts *opts, char *redundancy; Error *local_err = NULL; int ret; + char *backing_fmt = NULL; redundancy = qemu_opt_get_del(opts, BLOCK_OPT_REDUNDANCY); + backing_fmt = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FMT); + + if (backing_fmt && strcmp(backing_fmt, "sheepdog") != 0) { + error_setg(errp, "backing_file must be a sheepdog image"); + ret = -EINVAL; + goto fail; + } qdict = qemu_opts_to_qdict(opts, NULL); qdict_put_str(qdict, "driver", "sheepdog"); @@ -2232,6 +2240,7 @@ fail: qapi_free_BlockdevCreateOptions(create_options); qobject_unref(qdict); g_free(redundancy); + g_free(backing_fmt); return ret; } @@ -3189,6 +3198,11 @@ static QemuOptsList sd_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 'sheepdog' if present", + }, { .name = BLOCK_OPT_PREALLOC, .type = QEMU_OPT_STRING, -- 2.25.1