commit fe904ea8242cbae2d7e69c052c754b8f5f1ba1d6 fixed a case
which migration aborted QEMU because it didn't regain the control
of images while some errors happened.
Actually, there are another two cases can trigger the same error reports:
" bdrv_co_do_pwritev: Assertion `!(bs->open_flags & 0x0800)' failed",
Case 1, codes path:
migration_thread()
migration_completion()
bdrv_inactivate_all() ----------------> inactivate images
qemu_savevm_state_complete_precopy()
socket_writev_buffer() --------> error because destination fails
qemu_fflush() ----------------> set error on migration stream
-> qmp_migrate_cancel() ----------------> user cancelled migration concurrently
-> migrate_set_state() ------------------> set migrate CANCELLIN
migration_completion() -----------------> go on to fail_invalidate
if (s->state == MIGRATION_STATUS_ACTIVE) -> Jump this branch
Case 2, codes path:
migration_thread()
migration_completion()
bdrv_inactivate_all() ----------------> inactivate images
migreation_completion() finished
-> qmp_migrate_cancel() ---------------> user cancelled migration concurrently
qemu_mutex_lock_iothread();
qemu_bh_schedule (s->cleanup_bh);
As we can see from above, qmp_migrate_cancel can slip in whenever
migration_thread does not hold the global lock. If this happens after
bdrv_inactive_all() been called, the above error reports will appear.
To prevent this, we can call bdrv_invalidate_cache_all() in qmp_migrate_cancel()
directly if we find images become inactive.
Besides, bdrv_invalidate_cache_all() in migration_completion() doesn't have the
protection of big lock, fix it by add the missing qemu_mutex_lock_iothread();
Signed-off-by: zhanghailiang <zhang.zhanghaili...@huawei.com>
---
v2:
- Fix a bug introduced by commit fe904 which didn't get big lock
before call bdrv_invalidate_cache_all. (Suggested by Dave)
---
include/migration/migration.h | 3 +++
migration/migration.c | 15 +++++++++++++++
2 files changed, 18 insertions(+)
diff --git a/include/migration/migration.h b/include/migration/migration.h
index c309d23..2d5b724 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -177,6 +177,9 @@ struct MigrationState
/* Flag set once the migration thread is running (and needs joining) */
bool migration_thread_running;
+ /* Flag set once the migration thread called bdrv_inactivate_all */
+ bool block_inactive;
+
/* Queue of outstanding page requests from the destination */
QemuMutex src_page_req_mutex;
QSIMPLEQ_HEAD(src_page_requests, MigrationSrcPageRequest)
src_page_requests;
diff --git a/migration/migration.c b/migration/migration.c
index f498ab8..5b50afe 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1006,6 +1006,16 @@ static void migrate_fd_cancel(MigrationState *s)
if (s->state == MIGRATION_STATUS_CANCELLING && f) {
qemu_file_shutdown(f);
}
+ if (s->state == MIGRATION_STATUS_CANCELLING && s->block_inactive) {
+ Error *local_err = NULL;
+
+ bdrv_invalidate_cache_all(&local_err);
+ if (local_err) {
+ error_report_err(local_err);
+ } else {
+ s->block_inactive = false;
+ }
+ }
}
void add_migration_state_change_notifier(Notifier *notify)
@@ -1705,6 +1715,7 @@ static void migration_completion(MigrationState *s, int
current_active_state,
if (ret >= 0) {
qemu_file_set_rate_limit(s->to_dst_file, INT64_MAX);
qemu_savevm_state_complete_precopy(s->to_dst_file, false);
+ s->block_inactive = true;
}
}
qemu_mutex_unlock_iothread();
@@ -1755,10 +1766,14 @@ fail_invalidate:
if (s->state == MIGRATION_STATUS_ACTIVE) {
Error *local_err = NULL;
+ qemu_mutex_lock_iothread();
bdrv_invalidate_cache_all(&local_err);
if (local_err) {
error_report_err(local_err);
+ } else {
+ s->block_inactive = false;
}
+ qemu_mutex_unlock_iothread();
}
fail:
--
1.8.3.1
