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[Qemu-devel] [PATCH v2] migration: regain control of images when migrati
From: |
Greg Kurz |
Subject: |
[Qemu-devel] [PATCH v2] migration: regain control of images when migration fails to complete |
Date: |
Wed, 18 May 2016 15:44:36 +0200 |
User-agent: |
StGit/0.17.1-dirty |
We currently have an error path during migration that can cause
the source QEMU to abort:
migration_thread()
migration_completion()
runstate_is_running() ----------------> true if guest is running
bdrv_inactivate_all() ----------------> inactivate images
qemu_savevm_state_complete_precopy()
... qemu_fflush()
socket_writev_buffer() --------> error because destination fails
qemu_fflush() -------------------> set error on migration stream
migration_completion() -----------------> set migrate state to FAILED
migration_thread() -----------------------> break migration loop
vm_start() -----------------------------> restart guest with inactive
images
and you get:
qemu-system-ppc64: socket_writev_buffer: Got err=104 for
(32768/18446744073709551615)
qemu-system-ppc64:
/home/greg/Work/qemu/qemu-master/block/io.c:1342:bdrv_co_do_pwritev: Assertion
`!(bs->open_flags & 0x0800)' failed.
Aborted (core dumped)
If we try postcopy with a similar scenario, we also get the writev error
message but QEMU leaves the guest paused because entered_postcopy is true.
We could possibly do the same with precopy and leave the guest paused.
But since the historical default for migration errors is to restart the
source, this patch adds a call to bdrv_invalidate_cache_all() instead.
Signed-off-by: Greg Kurz <address@hidden>
---
v2: - follow the existing error handling patterns (Kevin)
---
migration/migration.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/migration/migration.c b/migration/migration.c
index 991313a8629a..0563b4c348e6 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1597,19 +1597,32 @@ static void migration_completion(MigrationState *s, int
current_active_state,
rp_error = await_return_path_close_on_source(s);
trace_migration_completion_postcopy_end_after_rp(rp_error);
if (rp_error) {
- goto fail;
+ goto fail_invalidate;
}
}
if (qemu_file_get_error(s->to_dst_file)) {
trace_migration_completion_file_err();
- goto fail;
+ goto fail_invalidate;
}
migrate_set_state(&s->state, current_active_state,
MIGRATION_STATUS_COMPLETED);
return;
+fail_invalidate:
+ /* If not doing postcopy, vm_start() will be called: let's regain
+ * control on images.
+ */
+ if (s->state == MIGRATION_STATUS_ACTIVE) {
+ Error *local_err = NULL;
+
+ bdrv_invalidate_cache_all(&local_err);
+ if (local_err) {
+ error_report_err(local_err);
+ }
+ }
+
fail:
migrate_set_state(&s->state, current_active_state,
MIGRATION_STATUS_FAILED);
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