Rather than creating stubs for every command that just return
QERR_UNSUPPORTED, use 'if' conditions in the QAPI schema to
fully exclude generation of the filesystem trimming commands
on POSIX platforms lacking required APIs.

The command will be rejected at QMP dispatch time instead,
avoiding reimplementing rejection by blocking the stub commands.

This has the additional benefit that the QGA protocol reference
now documents what conditions enable use of the command.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 qga/commands-posix.c | 13 -------------
 qga/qapi-schema.json |  9 ++++++---
 2 files changed, 6 insertions(+), 16 deletions(-)

diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index 9207cb7a8f..d92fa0ec87 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -1144,22 +1144,9 @@ error:
 
 #endif /* HAVE_GETIFADDRS */
 
-#if !defined(CONFIG_FSTRIM)
-GuestFilesystemTrimResponse *
-qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **errp)
-{
-    error_setg(errp, QERR_UNSUPPORTED);
-    return NULL;
-}
-#endif
-
 /* add unsupported commands to the list of blocked RPCs */
 GList *ga_command_init_blockedrpcs(GList *blockedrpcs)
 {
-#if !defined(CONFIG_FSTRIM)
-    blockedrpcs = g_list_append(blockedrpcs, g_strdup("guest-fstrim"));
-#endif
-
     return blockedrpcs;
 }
 
diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index 098fa7a08b..0f27375ea0 100644
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -509,7 +509,8 @@
 ##
 { 'struct': 'GuestFilesystemTrimResult',
   'data': {'path': 'str',
-           '*trimmed': 'int', '*minimum': 'int', '*error': 'str'} }
+           '*trimmed': 'int', '*minimum': 'int', '*error': 'str'},
+  'if': { 'any': ['CONFIG_WIN32', 'CONFIG_FSTRIM'] } }
 
 ##
 # @GuestFilesystemTrimResponse:
@@ -519,7 +520,8 @@
 # Since: 2.4
 ##
 { 'struct': 'GuestFilesystemTrimResponse',
-  'data': {'paths': ['GuestFilesystemTrimResult']} }
+  'data': {'paths': ['GuestFilesystemTrimResult']},
+  'if': { 'any': ['CONFIG_WIN32', 'CONFIG_FSTRIM'] } }
 
 ##
 # @guest-fstrim:
@@ -541,7 +543,8 @@
 ##
 { 'command': 'guest-fstrim',
   'data': { '*minimum': 'int' },
-  'returns': 'GuestFilesystemTrimResponse' }
+  'returns': 'GuestFilesystemTrimResponse',
+  'if': { 'any': ['CONFIG_WIN32', 'CONFIG_FSTRIM'] } }
 
 ##
 # @guest-suspend-disk:
-- 
2.45.1