-existing BDRV_REQ_NO_FALLBACK flag, in both client and server). But
-to actually get the NBD extension into the protocol, it's better to
-prove that the extension will be interoperable with other NBD
-implementations. So, the obvious second implementation is libnbd for
-a client (adding a new flag to nbd_zero, and support for mapping a new
-errno value, due out in 1.2), and nbdkit for a server (adding a new
-.can_fast_zero callback for plugins and filters, then methodically
-patching all in-tree files where it can be reasonably implemented,
-released in 1.14). Among other things, the nbdkit changes to the
-nozero filter added the parameters I used in my demo for controlling
-whether to advertise and/or honor the semantics of the new flag.
+existing BDRV_REQ_NO_FALLBACK flag, in both client and server, due out
+in qemu 4.2). But to actually get the NBD extension into the
+protocol, it's better to prove that the extension will be
+interoperable with other NBD implementations. So, the obvious second
+implementation is libnbd for a client (adding a new flag to nbd_zero,
+and support for mapping a new errno value, due out in 1.2), and nbdkit
+for a server (adding a new .can_fast_zero callback for plugins and
+filters, then methodically patching all in-tree files where it can be
+reasonably implemented, due out in 1.16). Among other things, the
+nbdkit changes to the nozero filter added the parameters I used in my
+demo for controlling whether to advertise and/or honor the semantics
+of the new flag.