migration: Remove fd: support on files

This feature was deprecated in 9.1.  Remove it in this release (11.0).

We also need to remove one unit test (/migration/precopy/fd/file) that
covers the fd: file migration, because it'll stop working now.

Reviewed-by: Prasad Pandit <ppandit@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20260115225503.3083355-3-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>

docs/about/deprecated.rst

@@ -518,17 +518,3 @@ If the user requests a modern x86 CPU model (i.e. not one of ``486``,
 ``athlon``, ``kvm32``, ``pentium``, ``pentium2``, ``pentium3``or ``qemu32``)
 a warning will be displayed until a future QEMU version when such CPUs will
 be rejected.
-
-Migration
----------
-
-``fd:`` URI when used for file migration (since 9.1)
-''''''''''''''''''''''''''''''''''''''''''''''''''''
-
-The ``fd:`` URI can currently provide a file descriptor that
-references either a socket or a plain file. These are two different
-types of migration. In order to reduce ambiguity, the ``fd:`` URI
-usage of providing a file descriptor to a plain file has been
-deprecated in favor of explicitly using the ``file:`` URI with the
-file descriptor being passed as an ``fdset``. Refer to the ``add-fd``
-command documentation for details on the ``fdset`` usage.

docs/about/removed-features.rst

@@ -716,6 +716,15 @@ Use blockdev-mirror with NBD instead. See "QMP invocation for live
 storage migration with ``blockdev-mirror`` + NBD" in
 docs/interop/live-block-operations.rst for a detailed explanation.
 
+``migrate`` command with file-based ``fd:`` URI (removed in 11.0)
+'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+In order to reduce ambiguity, the ``fd:`` URI usage of providing a
+file descriptor to a plain file has been removed in favor of
+explicitly using the ``file:`` URI with the file descriptor being
+passed as an ``fdset``. Refer to the ``add-fd`` command documentation
+for details on the ``fdset`` usage.
+
 ``migrate-set-capabilities`` ``block`` option (removed in 9.1)
 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
 

migration/fd.c

@@ -24,6 +24,7 @@
 #include "qemu/sockets.h"
 #include "io/channel-util.h"
 #include "trace.h"
+#include "qapi/error.h"
 
 static bool fd_is_pipe(int fd)
 {
@@ -58,8 +59,9 @@ void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **
     }
 
     if (!migration_fd_valid(fd)) {
-        warn_report("fd: migration to a file is deprecated."
-                    " Use file: instead.");
+        error_setg(errp, "fd: migration to a file is not supported."
+                   " Use file: instead.");
+        return;
     }
 
     trace_migration_fd_outgoing(fd);
@@ -92,8 +94,9 @@ void fd_start_incoming_migration(const char *fdname, Error **errp)
     }
 
     if (!migration_fd_valid(fd)) {
-        warn_report("fd: migration to a file is deprecated."
-                    " Use file: instead.");
+        error_setg(errp, "fd: migration to a file is not supported."
+                   " Use file: instead.");
+        return;
     }
 
     trace_migration_fd_incoming(fd);

tests/qtest/migration/precopy-tests.c

@@ -289,45 +289,6 @@ static void test_precopy_fd_socket(char *name, MigrateCommon *args)
 
     test_precopy_common(args);
 }
-
-static void *migrate_hook_start_precopy_fd_file(QTestState *from,
-                                                QTestState *to)
-{
-    g_autofree char *file = g_strdup_printf("%s/%s", tmpfs, FILE_TEST_FILENAME);
-    int src_flags = O_CREAT | O_RDWR;
-    int dst_flags = O_CREAT | O_RDWR;
-    int fds[2];
-
-    fds[0] = open(file, src_flags, 0660);
-    assert(fds[0] != -1);
-
-    fds[1] = open(file, dst_flags, 0660);
-    assert(fds[1] != -1);
-
-
-    qtest_qmp_fds_assert_success(to, &fds[0], 1,
-                                 "{ 'execute': 'getfd',"
-                                 "  'arguments': { 'fdname': 'fd-mig' }}");
-
-    qtest_qmp_fds_assert_success(from, &fds[1], 1,
-                                 "{ 'execute': 'getfd',"
-                                 "  'arguments': { 'fdname': 'fd-mig' }}");
-
-    close(fds[0]);
-    close(fds[1]);
-
-    return NULL;
-}
-
-static void test_precopy_fd_file(char *name, MigrateCommon *args)
-{
-    args->listen_uri = "defer";
-    args->connect_uri = "fd:fd-mig";
-    args->start_hook = migrate_hook_start_precopy_fd_file;
-    args->end_hook = migrate_hook_end_fd;
-
-    test_file_common(args, true);
-}
 #endif /* _WIN32 */
 
 /*
@@ -1255,8 +1216,6 @@ void migration_test_add_precopy(MigrationTestEnv *env)
 #ifndef _WIN32
     migration_test_add("/migration/precopy/fd/tcp",
                        test_precopy_fd_socket);
-    migration_test_add("/migration/precopy/fd/file",
-                       test_precopy_fd_file);
 #endif
 
     /*