fsdev: Error out when unsupported option is passed

Each fsdriver only supports a subset of the options that can be passed
to -fsdev. Unsupported options are simply ignored. This could cause the
user to erroneously think QEMU has a bug.

Enforce strict checking of supported options for all fsdrivers. This
shouldn't impact libvirt, since it doesn't know about the synth and
proxy fsdrivers.

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Eric Blake <eblake@redhat.com>

fsdev/qemu-fsdev.c

@@ -34,6 +34,7 @@
 typedef struct FsDriverTable {
     const char *name;
     FileOperations *ops;
+    const char **opts;
 } FsDriverTable;
 
 typedef struct FsDriverListEntry {
@@ -44,12 +45,75 @@ typedef struct FsDriverListEntry {
 static QTAILQ_HEAD(, FsDriverListEntry) fsdriver_entries =
     QTAILQ_HEAD_INITIALIZER(fsdriver_entries);
 
+#define COMMON_FS_DRIVER_OPTIONS "id", "fsdriver", "readonly"
+
 static FsDriverTable FsDrivers[] = {
-    { .name = "local", .ops = &local_ops},
-    { .name = "synth", .ops = &synth_ops},
-    { .name = "proxy", .ops = &proxy_ops},
+    {
+        .name = "local",
+        .ops = &local_ops,
+        .opts = (const char * []) {
+            COMMON_FS_DRIVER_OPTIONS,
+            "security_model",
+            "path",
+            "writeout",
+            "fmode",
+            "dmode",
+            "throttling.bps-total",
+            "throttling.bps-read",
+            "throttling.bps-write",
+            "throttling.iops-total",
+            "throttling.iops-read",
+            "throttling.iops-write",
+            "throttling.bps-total-max",
+            "throttling.bps-read-max",
+            "throttling.bps-write-max",
+            "throttling.iops-total-max",
+            "throttling.iops-read-max",
+            "throttling.iops-write-max",
+            "throttling.bps-total-max-length",
+            "throttling.bps-read-max-length",
+            "throttling.bps-write-max-length",
+            "throttling.iops-total-max-length",
+            "throttling.iops-read-max-length",
+            "throttling.iops-write-max-length",
+            "throttling.iops-size",
+        },
+    },
+    {
+        .name = "synth",
+        .ops = &synth_ops,
+        .opts = (const char * []) {
+            COMMON_FS_DRIVER_OPTIONS,
+        },
+    },
+    {
+        .name = "proxy",
+        .ops = &proxy_ops,
+        .opts = (const char * []) {
+            COMMON_FS_DRIVER_OPTIONS,
+            "socket",
+            "sock_fd",
+            "writeout",
+        },
+    },
 };
 
+static int validate_opt(void *opaque, const char *name, const char *value,
+                        Error **errp)
+{
+    FsDriverTable *drv = opaque;
+    const char **opt;
+
+    for (opt = drv->opts; *opt; opt++) {
+        if (!strcmp(*opt, name)) {
+            return 0;
+        }
+    }
+
+    error_setg(errp, "'%s' is invalid for fsdriver '%s'", name, drv->name);
+    return -1;
+}
+
 int qemu_fsdev_add(QemuOpts *opts, Error **errp)
 {
     int i;
@@ -80,6 +144,10 @@ int qemu_fsdev_add(QemuOpts *opts, Error **errp)
         return -1;
     }
 
+    if (qemu_opt_foreach(opts, validate_opt, &FsDrivers[i], errp)) {
+        return -1;
+    }
+
     fsle = g_malloc0(sizeof(*fsle));
     fsle->fse.fsdev_id = g_strdup(fsdev_id);
     fsle->fse.ops = FsDrivers[i].ops;