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[Qemu-block] [PULL 11/17] block: Inactivate BDS when migration completes
From: |
Kevin Wolf |
Subject: |
[Qemu-block] [PULL 11/17] block: Inactivate BDS when migration completes |
Date: |
Wed, 20 Jan 2016 17:25:00 +0100 |
So far, live migration with shared storage meant that the image is in a
not-really-ready don't-touch-me state on the destination while the
source is still actively using it, but after completing the migration,
the image was fully opened on both sides. This is bad.
This patch adds a block driver callback to inactivate images on the
source before completing the migration. Inactivation means that it goes
to a state as if it was just live migrated to the qemu instance on the
source (i.e. BDRV_O_INACTIVE is set). You're then supposed to continue
either on the source or on the destination, which takes ownership of the
image.
A typical migration looks like this now with respect to disk images:
1. Destination qemu is started, the image is opened with
BDRV_O_INACTIVE. The image is fully opened on the source.
2. Migration is about to complete. The source flushes the image and
inactivates it. Now both sides have the image opened with
BDRV_O_INACTIVE and are expecting the other side to still modify it.
3. One side (the destination on success) continues and calls
bdrv_invalidate_all() in order to take ownership of the image again.
This removes BDRV_O_INACTIVE on the resuming side; the flag remains
set on the other side.
This ensures that the same image isn't written to by both instances
(unless both are resumed, but then you get what you deserve). This is
important because .bdrv_close for non-BDRV_O_INACTIVE images could write
to the image file, which is definitely forbidden while another host is
using the image.
Signed-off-by: Kevin Wolf <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Reviewed-by: John Snow <address@hidden>
---
block.c | 34 ++++++++++++++++++++++++++++++++++
include/block/block.h | 1 +
include/block/block_int.h | 1 +
migration/migration.c | 7 +++++++
qmp.c | 12 ++++++++++++
5 files changed, 55 insertions(+)
diff --git a/block.c b/block.c
index 95b2967..5709d3d 100644
--- a/block.c
+++ b/block.c
@@ -3303,6 +3303,40 @@ void bdrv_invalidate_cache_all(Error **errp)
}
}
+static int bdrv_inactivate(BlockDriverState *bs)
+{
+ int ret;
+
+ if (bs->drv->bdrv_inactivate) {
+ ret = bs->drv->bdrv_inactivate(bs);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+
+ bs->open_flags |= BDRV_O_INACTIVE;
+ return 0;
+}
+
+int bdrv_inactivate_all(void)
+{
+ BlockDriverState *bs;
+ int ret;
+
+ QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
+ AioContext *aio_context = bdrv_get_aio_context(bs);
+
+ aio_context_acquire(aio_context);
+ ret = bdrv_inactivate(bs);
+ aio_context_release(aio_context);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
/**************************************************************/
/* removable device support */
diff --git a/include/block/block.h b/include/block/block.h
index 2b7d33c..25f36dc 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -369,6 +369,7 @@ BlockAIOCB *bdrv_aio_ioctl(BlockDriverState *bs,
/* Invalidate any cached metadata used by image formats */
void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp);
void bdrv_invalidate_cache_all(Error **errp);
+int bdrv_inactivate_all(void);
/* Ensure contents are flushed to disk. */
int bdrv_flush(BlockDriverState *bs);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 256609d..428fa33 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -172,6 +172,7 @@ struct BlockDriver {
* Invalidate any cached meta-data.
*/
void (*bdrv_invalidate_cache)(BlockDriverState *bs, Error **errp);
+ int (*bdrv_inactivate)(BlockDriverState *bs);
/*
* Flushes all data that was already written to the OS all the way down to
diff --git a/migration/migration.c b/migration/migration.c
index bc611e4..aaca451 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1422,7 +1422,11 @@ static int postcopy_start(MigrationState *ms, bool
*old_vm_running)
*old_vm_running = runstate_is_running();
global_state_store();
ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
+ if (ret < 0) {
+ goto fail;
+ }
+ ret = bdrv_inactivate_all();
if (ret < 0) {
goto fail;
}
@@ -1542,6 +1546,9 @@ static void migration_completion(MigrationState *s, int
current_active_state,
if (!ret) {
ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
if (ret >= 0) {
+ ret = bdrv_inactivate_all();
+ }
+ if (ret >= 0) {
qemu_file_set_rate_limit(s->file, INT64_MAX);
qemu_savevm_state_complete_precopy(s->file, false);
}
diff --git a/qmp.c b/qmp.c
index 3ff6db7..53affe2 100644
--- a/qmp.c
+++ b/qmp.c
@@ -192,6 +192,18 @@ void qmp_cont(Error **errp)
}
}
+ /* Continuing after completed migration. Images have been inactivated to
+ * allow the destination to take control. Need to get control back now. */
+ if (runstate_check(RUN_STATE_FINISH_MIGRATE) ||
+ runstate_check(RUN_STATE_POSTMIGRATE))
+ {
+ bdrv_invalidate_cache_all(&local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ return;
+ }
+ }
+
if (runstate_check(RUN_STATE_INMIGRATE)) {
autostart = 1;
} else {
--
1.8.3.1
- [Qemu-block] [PULL 01/17] block: Fix .bdrv_open flags, (continued)
- [Qemu-block] [PULL 01/17] block: Fix .bdrv_open flags, Kevin Wolf, 2016/01/20
- [Qemu-block] [PULL 04/17] qemu-iotests: Reduce racy output in 028, Kevin Wolf, 2016/01/20
- [Qemu-block] [PULL 08/17] block: Assert no write requests under BDRV_O_INCOMING, Kevin Wolf, 2016/01/20
- [Qemu-block] [PULL 07/17] qcow2: Write full header on image creation, Kevin Wolf, 2016/01/20
- [Qemu-block] [PULL 09/17] block: Fix error path in bdrv_invalidate_cache(), Kevin Wolf, 2016/01/20
- [Qemu-block] [PULL 06/17] qcow2: Write feature table only for v3 images, Kevin Wolf, 2016/01/20
- [Qemu-block] [PULL 10/17] block: Rename BDRV_O_INCOMING to BDRV_O_INACTIVE, Kevin Wolf, 2016/01/20
- [Qemu-block] [PULL 12/17] qcow2: Implement .bdrv_inactivate, Kevin Wolf, 2016/01/20
- [Qemu-block] [PULL 05/17] block: Clean up includes, Kevin Wolf, 2016/01/20
- [Qemu-block] [PULL 11/17] block: Inactivate BDS when migration completes,
Kevin Wolf <=
- [Qemu-block] [PULL 13/17] qcow2: Fix BDRV_O_INACTIVE handling in qcow2_invalidate_cache(), Kevin Wolf, 2016/01/20
- [Qemu-block] [PULL 14/17] qcow2: Make image inaccessible after failed qcow2_invalidate_cache(), Kevin Wolf, 2016/01/20
- [Qemu-block] [PULL 15/17] vmdk: Create streamOptimized as version 3, Kevin Wolf, 2016/01/20
- [Qemu-block] [PULL 17/17] iotests: Test that throttle values ranges, Kevin Wolf, 2016/01/20
- [Qemu-block] [PULL 16/17] blockdev: Error out on negative throttling option values, Kevin Wolf, 2016/01/20
- Re: [Qemu-block] [Qemu-devel] [PULL 00/17] Block patches, Peter Maydell, 2016/01/21