[RFC PATCH v1 18/26] migration/multifd: Add incoming QIOChannelFile support

[Fabiano Rosas]

On the receiving side we don't need to differentiate between main
channel and threads, so whichever channel is defined first gets to be
the main one. And since there are no packets, use the atomic channel
count to index into the params array.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/file.c      | 38 +++++++++++++++++++++++++++++++++-----
 migration/migration.c |  2 ++
 migration/multifd.c   |  7 ++++++-
 migration/multifd.h   |  1 +
 4 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/migration/file.c b/migration/file.c
index f674cd1bdb..6f40894488 100644
--- a/migration/file.c
+++ b/migration/file.c
@@ -2,6 +2,7 @@
 #include "io/channel-file.h"
 #include "file.h"
 #include "qemu/error-report.h"
+#include "migration.h"
 
 static struct FileOutgoingArgs {
     char *fname;
@@ -77,17 +78,44 @@ void file_start_outgoing_migration(MigrationState *s, const 
char *fname, Error *
     object_unref(OBJECT(ioc));
 }
 
+static void file_process_migration_incoming(QIOTask *task, gpointer opaque)
+{
+    QIOChannelFile *ioc = opaque;
+
+    migration_channel_process_incoming(QIO_CHANNEL(ioc));
+    object_unref(OBJECT(ioc));
+}
+
 void file_start_incoming_migration(const char *fname, Error **errp)
 {
     QIOChannelFile *ioc;
+    QIOTask *task;
+    int channels = 1;
+    int i = 0, fd;
 
     ioc = qio_channel_file_new_path(fname, O_RDONLY, 0, errp);
     if (!ioc) {
-        error_report("Error creating a channel");
+        goto out;
+    }
+
+    if (migrate_use_multifd()) {
+        channels += migrate_multifd_channels();
+    }
+
+    fd = ioc->fd;
+
+    do {
+        qio_channel_set_name(QIO_CHANNEL(ioc), "migration-file-incoming");
+        task = qio_task_new(OBJECT(ioc), file_process_migration_incoming,
+                            (gpointer)ioc, NULL);
+
+        qio_task_run_in_thread(task, qio_channel_file_connect_worker,
+                               (gpointer)ioc, NULL, NULL);
+    } while (++i < channels && (ioc = qio_channel_file_new_fd(fd)));
+
+out:
+    if (!ioc) {
+        error_report("Error creating migration incoming channel");
         return;
     }
-
-    qio_channel_set_name(QIO_CHANNEL(ioc), "migration-file-incoming");
-    migration_channel_process_incoming(QIO_CHANNEL(ioc));
-    object_unref(OBJECT(ioc));
 }
diff --git a/migration/migration.c b/migration/migration.c
index 6594c2f404..258709aee1 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -794,6 +794,8 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error 
**errp)
         }
 
         default_channel = (channel_magic == cpu_to_be32(QEMU_VM_FILE_MAGIC));
+    } else if (migrate_use_multifd() && migrate_fixed_ram()) {
+        default_channel = multifd_recv_first_channel();
     } else {
         default_channel = !mis->from_src_file;
     }
diff --git a/migration/multifd.c b/migration/multifd.c
index 50bd9b32eb..1332b426ce 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -1254,6 +1254,11 @@ int multifd_load_setup(Error **errp)
     return 0;
 }
 
+bool multifd_recv_first_channel(void)
+{
+    return !multifd_recv_state;
+}
+
 bool multifd_recv_all_channels_created(void)
 {
     int thread_count = migrate_multifd_channels();
@@ -1296,7 +1301,7 @@ void multifd_recv_new_channel(QIOChannel *ioc, Error 
**errp)
         /* initial packet */
         num_packets = 1;
     } else {
-        id = 0;
+        id = qatomic_read(&multifd_recv_state->count);
     }
 
     p = &multifd_recv_state->params[id];
diff --git a/migration/multifd.h b/migration/multifd.h
index 7cfc265148..354150ff55 100644
--- a/migration/multifd.h
+++ b/migration/multifd.h
@@ -18,6 +18,7 @@ void multifd_save_cleanup(void);
 int multifd_load_setup(Error **errp);
 void multifd_load_cleanup(void);
 void multifd_load_shutdown(void);
+bool multifd_recv_first_channel(void);
 bool multifd_recv_all_channels_created(void);
 void multifd_recv_new_channel(QIOChannel *ioc, Error **errp);
 void multifd_recv_sync_main(void);
-- 
2.35.3