The idea behind this implementation is that the export name might be interpreted as a path (which is the only apparent interpretation of relative filenames for NBD paths).
The default implementation of bdrv_dirname() would handle that just fine for nbd+tcp, but not for nbd+unix, because in that case, the last element of the path is the Unix socket path and not the export name. Therefore, we need to implement an own bdrv_dirname() which uses the legacy NBD URL which has the export name at the end. Signed-off-by: Max Reitz <mre...@redhat.com> --- block/nbd.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/block/nbd.c b/block/nbd.c index 35f24be..42f0cd6 100644 --- a/block/nbd.c +++ b/block/nbd.c @@ -552,6 +552,34 @@ static void nbd_refresh_filename(BlockDriverState *bs, QDict *options) bs->full_open_options = opts; } +static char *nbd_dirname(BlockDriverState *bs, Error **errp) +{ + BDRVNBDState *s = bs->opaque; + const char *host = NULL, *port = NULL, *path = NULL; + + if (s->saddr->type == SOCKET_ADDRESS_KIND_INET) { + const InetSocketAddress *inet = s->saddr->u.inet.data; + if (!inet->has_ipv4 && !inet->has_ipv6 && !inet->has_to) { + host = inet->host; + port = inet->port; + } + } else if (s->saddr->type == SOCKET_ADDRESS_KIND_UNIX) { + path = s->saddr->u.q_unix.data->path; + } + + if (path) { + return g_strdup_printf("nbd:unix:%s:exportname=%s%s", path, + s->export ?: "", s->export ? "/" : ""); + } else if (host) { + return g_strdup_printf("nbd://%s:%s/%s%s", host, port, + s->export ?: "", s->export ? "/" : ""); + } + + error_setg(errp, "Cannot generate a base directory for NBD node '%s'", + bs->filename); + return NULL; +} + static BlockDriver bdrv_nbd = { .format_name = "nbd", .protocol_name = "nbd", @@ -569,6 +597,7 @@ static BlockDriver bdrv_nbd = { .bdrv_detach_aio_context = nbd_detach_aio_context, .bdrv_attach_aio_context = nbd_attach_aio_context, .bdrv_refresh_filename = nbd_refresh_filename, + .bdrv_dirname = nbd_dirname, }; static BlockDriver bdrv_nbd_tcp = { @@ -588,6 +617,7 @@ static BlockDriver bdrv_nbd_tcp = { .bdrv_detach_aio_context = nbd_detach_aio_context, .bdrv_attach_aio_context = nbd_attach_aio_context, .bdrv_refresh_filename = nbd_refresh_filename, + .bdrv_dirname = nbd_dirname, }; static BlockDriver bdrv_nbd_unix = { @@ -607,6 +637,7 @@ static BlockDriver bdrv_nbd_unix = { .bdrv_detach_aio_context = nbd_detach_aio_context, .bdrv_attach_aio_context = nbd_attach_aio_context, .bdrv_refresh_filename = nbd_refresh_filename, + .bdrv_dirname = nbd_dirname, }; static void bdrv_nbd_init(void) -- 2.10.2