[Qemu-devel] [PATCH 16/18] migration: introduce migrate_ft_trans_{put, get}_ready(), and modify migrate_fd_put_ready() when ft_mode is on.

[Yoshiaki Tamura]

Introduce migrate_ft_trans_put_ready() which kicks the FT transaction
cycle.  When ft_mode is on, migrate_fd_put_ready() would open
ft_trans_file and turn on event_tap.  To end or cancel FT transaction,
ft_mode and event_tap is turned off.  migrate_ft_trans_get_ready() is
called to receive ack from the receiver.

Signed-off-by: Yoshiaki Tamura <address@hidden>
---
 migration.c |  266 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 265 insertions(+), 1 deletions(-)

diff --git a/migration.c b/migration.c
index 1c2d956..d536df0 100644
--- a/migration.c
+++ b/migration.c
@@ -21,6 +21,7 @@
 #include "qemu_socket.h"
 #include "block-migration.h"
 #include "qemu-objects.h"
+#include "event-tap.h"
 
 //#define DEBUG_MIGRATION
 
@@ -283,6 +284,17 @@ void migrate_fd_error(FdMigrationState *s)
     migrate_fd_cleanup(s);
 }
 
+static void migrate_ft_trans_error(FdMigrationState *s)
+{
+    ft_mode = FT_ERROR;
+    qemu_savevm_state_cancel(s->mon, s->file);
+    migrate_fd_error(s);
+    /* we need to set vm running to avoid assert in virtio-net */
+    vm_start();
+    event_tap_unregister();
+    vm_stop(0);
+}
+
 int migrate_fd_cleanup(FdMigrationState *s)
 {
     int ret = 0;
@@ -318,6 +330,17 @@ void migrate_fd_put_notify(void *opaque)
     qemu_file_put_notify(s->file);
 }
 
+static void migrate_fd_get_notify(void *opaque)
+{
+    FdMigrationState *s = opaque;
+
+    qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
+    qemu_file_get_notify(s->file);
+    if (qemu_file_has_error(s->file)) {
+        migrate_ft_trans_error(s);
+    }
+}
+
 ssize_t migrate_fd_put_buffer(void *opaque, const void *data, size_t size)
 {
     FdMigrationState *s = opaque;
@@ -353,6 +376,10 @@ int migrate_fd_get_buffer(void *opaque, uint8_t *data, 
int64_t pos, size_t size)
         ret = -(s->get_error(s));
     }
 
+    if (ret == -EAGAIN) {
+        qemu_set_fd_handler2(s->fd, NULL, migrate_fd_get_notify, NULL, s);
+    }
+
     return ret;
 }
 
@@ -379,6 +406,230 @@ void migrate_fd_connect(FdMigrationState *s)
     migrate_fd_put_ready(s);
 }
 
+static int migrate_ft_trans_commit(void *opaque)
+{
+    FdMigrationState *s = opaque;
+    int ret = -1;
+
+    if (ft_mode != FT_TRANSACTION_COMMIT && ft_mode != FT_TRANSACTION_ATOMIC) {
+        fprintf(stderr,
+                "migrate_ft_trans_commit: invalid ft_mode %d\n", ft_mode);
+        goto out;
+    }
+
+    do {
+        if (ft_mode == FT_TRANSACTION_ATOMIC) {
+            if (qemu_ft_trans_begin(s->file) < 0) {
+                fprintf(stderr, "qemu_ft_trans_begin failed\n");
+                goto out;
+            }
+
+            ret = qemu_savevm_trans_begin(s->mon, s->file, 0);
+            if (ret < 0) {
+                fprintf(stderr, "qemu_savevm_trans_begin failed\n");
+                goto out;
+            }
+
+            ft_mode = FT_TRANSACTION_COMMIT;
+            if (ret) {
+                /* don't proceed until if fd isn't ready */
+                goto out;
+            }
+        }
+
+        /* make the VM state consistent by flushing outstanding events */
+        vm_stop(0);
+
+        /* send at full speed */
+        qemu_file_set_rate_limit(s->file, 0);
+
+        ret = qemu_savevm_trans_complete(s->mon, s->file);
+        if (ret < 0) {
+            fprintf(stderr, "qemu_savevm_trans_complete failed\n");
+            goto out;
+        }
+
+        ret = qemu_ft_trans_commit(s->file);
+        if (ret < 0) {
+            fprintf(stderr, "qemu_ft_trans_commit failed\n");
+            goto out;
+        }
+
+        if (ret) {
+            ft_mode = FT_TRANSACTION_RECV;
+            ret = 1;
+            goto out;
+        }
+
+        /* flush and check if events are remaining */
+        vm_start();
+        ret = event_tap_flush_one();
+        if (ret < 0) {
+            fprintf(stderr, "event_tap_flush_one failed\n");
+            goto out;
+        }
+
+        ft_mode =  ret ? FT_TRANSACTION_BEGIN : FT_TRANSACTION_ATOMIC;
+    } while (ft_mode != FT_TRANSACTION_BEGIN);
+
+    vm_start();
+    ret = 0;
+
+out:
+    return ret;
+}
+
+static int migrate_ft_trans_get_ready(void *opaque)
+{
+    FdMigrationState *s = opaque;
+    int ret = -1;
+
+    if (ft_mode != FT_TRANSACTION_RECV) {
+        fprintf(stderr,
+                "migrate_ft_trans_get_ready: invalid ft_mode %d\n", ft_mode);
+        goto error_out;
+    }
+
+    /* flush and check if events are remaining */
+    vm_start();
+    ret = event_tap_flush_one();
+    if (ret < 0) {
+        fprintf(stderr, "event_tap_flush_one failed\n");
+        goto error_out;
+    }
+
+    if (ret) {
+        ft_mode = FT_TRANSACTION_BEGIN;
+    } else {
+        ft_mode = FT_TRANSACTION_ATOMIC;
+
+        ret = migrate_ft_trans_commit(s);
+        if (ret < 0) {
+            goto error_out;
+        }
+        if (ret) {
+            goto out;
+        }
+    }
+
+    vm_start();
+    ret = 0;
+    goto out;
+
+error_out:
+    migrate_ft_trans_error(s);
+
+out:
+    return ret;
+}
+
+static int migrate_ft_trans_put_ready(void)
+{
+    FdMigrationState *s = migrate_to_fms(current_migration);
+    int ret = -1, init = 0, timeout;
+    static int64_t start, now;
+
+    switch (ft_mode) {
+    case FT_INIT:
+        init = 1;
+        ft_mode = FT_TRANSACTION_BEGIN;
+    case FT_TRANSACTION_BEGIN:
+        now = start = qemu_get_clock_ns(vm_clock);
+        /* start transatcion at best effort */
+        qemu_file_set_rate_limit(s->file, 1);
+
+        if (qemu_ft_trans_begin(s->file) < 0) {
+            fprintf(stderr, "qemu_transaction_begin failed\n");
+            goto error_out;
+        }
+
+        vm_stop(0);
+
+        ret = qemu_savevm_trans_begin(s->mon, s->file, init);
+        if (ret < 0) {
+            fprintf(stderr, "qemu_savevm_trans_begin\n");
+            goto error_out;
+        }
+
+        if (ret) {
+            ft_mode = FT_TRANSACTION_ITER;
+            vm_start();
+        } else {
+            ft_mode = FT_TRANSACTION_COMMIT;
+            if (migrate_ft_trans_commit(s) < 0) {
+                goto error_out;
+            }
+        }
+        break;
+
+    case FT_TRANSACTION_ITER:
+        now = qemu_get_clock_ns(vm_clock);
+        timeout = ((now - start) >= max_downtime);
+        if (timeout || qemu_savevm_state_iterate(s->mon, s->file) == 1) {
+            DPRINTF("ft trans iter timeout %d\n", timeout);
+
+            ft_mode = FT_TRANSACTION_COMMIT;
+            if (migrate_ft_trans_commit(s) < 0) {
+                goto error_out;
+            }
+            return 1;
+        }
+
+        ft_mode = FT_TRANSACTION_ITER;
+        break;
+
+    case FT_TRANSACTION_ATOMIC:
+    case FT_TRANSACTION_COMMIT:
+        if (migrate_ft_trans_commit(s) < 0) {
+            goto error_out;
+        }
+        break;
+
+    default:
+        fprintf(stderr,
+                "migrate_ft_trans_put_ready: invalid ft_mode %d", ft_mode);
+        goto error_out;
+    }
+
+    ret = 0;
+    goto out;
+
+error_out:
+    migrate_ft_trans_error(s);
+
+out:
+    return ret;
+}
+
+static void migrate_ft_trans_connect(FdMigrationState *s, int old_vm_running)
+{
+    /* close buffered_file and open ft_trans_file
+     * NB: fd won't get closed, and reused by ft_trans_file
+     */
+    qemu_fclose(s->file);
+
+    s->file = qemu_fopen_ops_ft_trans(s,
+                                      migrate_fd_put_buffer,
+                                      migrate_fd_get_buffer,
+                                      migrate_ft_trans_put_ready,
+                                      migrate_ft_trans_get_ready,
+                                      migrate_fd_wait_for_unfreeze,
+                                      migrate_fd_close,
+                                      1);
+    socket_set_nodelay(s->fd);
+
+    /* events are tapped from now */
+    if (event_tap_register(migrate_ft_trans_put_ready) < 0) {
+        migrate_ft_trans_error(s);
+    }
+
+    event_tap_schedule_suspend();
+
+    if (old_vm_running) {
+        vm_start();
+    }
+}
+
 void migrate_fd_put_ready(void *opaque)
 {
     FdMigrationState *s = opaque;
@@ -404,6 +655,11 @@ void migrate_fd_put_ready(void *opaque)
         } else {
             state = MIG_STATE_COMPLETED;
         }
+
+        if (ft_mode && state == MIG_STATE_COMPLETED) {
+            return migrate_ft_trans_connect(s, old_vm_running);
+        }
+
         if (migrate_fd_cleanup(s) < 0) {
             if (old_vm_running) {
                 vm_start();
@@ -432,8 +688,16 @@ void migrate_fd_cancel(MigrationState *mig_state)
 
     s->state = MIG_STATE_CANCELLED;
     notifier_list_notify(&migration_state_notifiers);
-    qemu_savevm_state_cancel(s->mon, s->file);
 
+    if (ft_mode) {
+        if (s->file) {
+            qemu_ft_trans_cancel(s->file);
+        }
+        ft_mode = FT_OFF;
+        event_tap_unregister();
+    }
+
+    qemu_savevm_state_cancel(s->mon, s->file);
     migrate_fd_cleanup(s);
 }
 
-- 
1.7.1.2