rbd: Clean up runtime_opts, fix -drive to reject filename

runtime_opts is used for three different purposes:

* qemu_rbd_open() uses it to accept options it recognizes, such as
  "pool" and "image".  Other .bdrv_open() methods do it similarly.

* qemu_rbd_open() accepts additional list-valued options
  auth-supported and server, with the help of qemu_rbd_array_opts().
  The list elements are again dictionaries.  qemu_rbd_array_opts()
  uses runtime_opts to accept their members.  Thus, runtime_opts
  contains recognized sub-sub-options "auth", "host", "port" in
  addition to recognized options.  No other block driver does that.

* qemu_rbd_create() uses it to convert the QDict produced by
  qemu_rbd_parse_filename() to QemuOpts.  No other block driver does
  that.  The keys produced by qemu_rbd_parse_filename() are "pool",
  "image", "snapshot", "conf", "user" and "keyvalue-pairs".
  qemu_rbd_open() accepts these, so no additional ones here.

This is a confusing mess.  Dates back to commit 0f9d252d.  First step
to clean it up is documenting runtime_opts.desc[]:

* Reorder entries to match the QAPI schema, like we do in other block
  drivers.

* Document why the schema's "server" and "auth-supported" aren't in
  .desc[].

* Document why "keyvalue-pairs", "host", "port" and "auth" are in
  .desc[], but not the schema.

* Delete "filename", because none of the three users actually uses it.
  This fixes -drive to reject parameter filename instead of silently
  ignoring it.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NJeff Cody <jcody@redhat.com>
Message-id: 1490691368-32099-7-git-send-email-armbru@redhat.com
Signed-off-by: NJeff Cody <jcody@redhat.com>

block/rbd.c

@@ -294,30 +294,20 @@ static QemuOptsList runtime_opts = {
     .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
     .desc = {
         {
-            .name = "filename",
+            .name = "pool",
             .type = QEMU_OPT_STRING,
-            .help = "Specification of the rbd image",
+            .help = "Rados pool name",
         },
         {
-            .name = "password-secret",
+            .name = "image",
             .type = QEMU_OPT_STRING,
-            .help = "ID of secret providing the password",
+            .help = "Image name in the pool",
         },
         {
             .name = "conf",
             .type = QEMU_OPT_STRING,
             .help = "Rados config file location",
         },
-        {
-            .name = "pool",
-            .type = QEMU_OPT_STRING,
-            .help = "Rados pool name",
-        },
-        {
-            .name = "image",
-            .type = QEMU_OPT_STRING,
-            .help = "Image name in the pool",
-        },
         {
             .name = "snapshot",
             .type = QEMU_OPT_STRING,
@@ -329,6 +319,19 @@ static QemuOptsList runtime_opts = {
             .type = QEMU_OPT_STRING,
             .help = "Rados id name",
         },
+        /*
+         * server.* and auth-supported.* extracted manually, see
+         * qemu_rbd_array_opts()
+         */
+        {
+            .name = "password-secret",
+            .type = QEMU_OPT_STRING,
+            .help = "ID of secret providing the password",
+        },
+
+        /*
+         * Keys for qemu_rbd_parse_filename(), not in the QAPI schema
+         */
         {
             /*
              * HACK: name starts with '=' so that qemu_opts_parse()
@@ -338,6 +341,13 @@ static QemuOptsList runtime_opts = {
             .type = QEMU_OPT_STRING,
             .help = "Legacy rados key/value option parameters",
         },
+
+        /*
+         * The remainder aren't option keys, but option sub-sub-keys,
+         * so that qemu_rbd_array_opts() can abuse runtime_opts for
+         * its own purposes
+         * TODO clean this up
+         */
         {
             .name = "host",
             .type = QEMU_OPT_STRING,