Just as the scenario of non-shared disk block replication,
we are going to implement block replication from many basic
blocks that are already in QEMU.
The architecture is:
virtio-blk || .----------
/ || | Secondary
/ || '----------
/ || virtio-blk
/ || |
| || replication(5)
| NBD --------> NBD (2) |
| client || server ---> hidden disk <-- active disk(4)
| ^ || |
| replication(1) || |
| | || |
| +-----------------' || |
(3) |drive-backup sync=none || |
--------. | +-----------------+ || |
Primary | | | || backing |
--------' | | || |
V | |
+-------------------------------------------+ |
| shared disk | <----------+
+-------------------------------------------+
1) Primary writes will read original data and forward it to Secondary
QEMU.
2) The hidden-disk is created automatically. It buffers the original content
that is modified by the primary VM. It should also be an empty disk, and
the driver supports bdrv_make_empty() and backing file.
3) Primary write requests will be written to Shared disk.
4) Secondary write requests will be buffered in the active disk and it
will overwrite the existing sector content in the buffer.
Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
---
v4:
- Call bdrv_invalidate_cache() while do checkpoint for shared disk
---
block/replication.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 52 insertions(+), 6 deletions(-)
diff --git a/block/replication.c b/block/replication.c
index 3a35471..fb604e5 100644
--- a/block/replication.c
+++ b/block/replication.c
@@ -253,7 +253,7 @@ static coroutine_fn int replication_co_readv(BlockDriverState *bs,
QEMUIOVector *qiov)
{
BDRVReplicationState *s = bs->opaque;
- BdrvChild *child = s->secondary_disk;
+ BdrvChild *child = s->is_shared_disk ? s->primary_disk : s->secondary_disk;
BlockJob *job = NULL;
CowRequest req;
int ret;
@@ -435,7 +435,12 @@ static void backup_job_completed(void *opaque, int ret)
s->error = -EIO;
}
- backup_job_cleanup(bs);
+ if (s->mode == REPLICATION_MODE_PRIMARY) {
+ s->replication_state = BLOCK_REPLICATION_DONE;
+ s->error = 0;
+ } else {
+ backup_job_cleanup(bs);
+ }
}
static bool check_top_bs(BlockDriverState *top_bs, BlockDriverState *bs)
@@ -487,6 +492,19 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
switch (s->mode) {
case REPLICATION_MODE_PRIMARY:
+ if (s->is_shared_disk) {
+ job = backup_job_create(NULL, s->primary_disk->bs, bs, 0,
+ MIRROR_SYNC_MODE_NONE, NULL, false, BLOCKDEV_ON_ERROR_REPORT,
+ BLOCKDEV_ON_ERROR_REPORT, BLOCK_JOB_INTERNAL,
+ backup_job_completed, bs, NULL, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ backup_job_cleanup(bs);
+ aio_context_release(aio_context);
+ return;
+ }
+ block_job_start(job);
+ }
break;
case REPLICATION_MODE_SECONDARY:
s->active_disk = bs->file;
@@ -505,7 +523,8 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
}
s->secondary_disk = s->hidden_disk->bs->backing;
- if (!s->secondary_disk->bs || !bdrv_has_blk(s->secondary_disk->bs)) {
+ if (!s->secondary_disk->bs ||
+ (!s->is_shared_disk && !bdrv_has_blk(s->secondary_disk->bs))) {
error_setg(errp, "The secondary disk doesn't have block backend");
aio_context_release(aio_context);
return;
@@ -600,11 +619,24 @@ static void replication_do_checkpoint(ReplicationState *rs, Error **errp)
switch (s->mode) {
case REPLICATION_MODE_PRIMARY:
+ if (s->is_shared_disk) {
+ if (!s->primary_disk->bs->job) {
+ error_setg(errp, "Primary backup job was cancelled"
+ " unexpectedly");
+ break;
+ }
+
+ backup_do_checkpoint(s->primary_disk->bs->job, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ }
+ }
break;
case REPLICATION_MODE_SECONDARY:
if (!s->is_shared_disk) {
if (!s->secondary_disk->bs->job) {
- error_setg(errp, "Backup job was cancelled unexpectedly");
+ error_setg(errp, "Secondary backup job was cancelled"
+ " unexpectedly");
break;
}
backup_do_checkpoint(s->secondary_disk->bs->job, &local_err);
@@ -612,6 +644,16 @@ static void replication_do_checkpoint(ReplicationState *rs, Error **errp)
error_propagate(errp, local_err);
break;
}
+ } else {
+ /*
+ * For shared disk, we need to force SVM to re-read metadata
+ * that is loaded in memory, or there will be inconsistent.
+ */
+ bdrv_invalidate_cache(s->secondary_disk->bs, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ break;
+ }
}
secondary_do_checkpoint(s, errp);
break;
@@ -683,8 +725,12 @@ static void replication_stop(ReplicationState *rs, bool failover, Error **errp)
switch (s->mode) {
case REPLICATION_MODE_PRIMARY:
- s->replication_state = BLOCK_REPLICATION_DONE;
- s->error = 0;
+ if (s->is_shared_disk && s->primary_disk->bs->job) {
+ block_job_cancel(s->primary_disk->bs->job);
+ } else {
+ s->replication_state = BLOCK_REPLICATION_DONE;
+ s->error = 0;
+ }
break;
case REPLICATION_MODE_SECONDARY:
/*
--
1.8.3.1
On Wed, Apr 12, 2017 at 10:05:20PM +0800, zhanghailiang wrote:
> @@ -612,6 +644,16 @@ static void replication_do_checkpoint(ReplicationState *rs, Error **errp)
> error_propagate(errp, local_err);
> break;
> }
> + } else {
> + /*
> + * For shared disk, we need to force SVM to re-read metadata
> + * that is loaded in memory, or there will be inconsistent.
> + */
> + bdrv_invalidate_cache(s->secondary_disk->bs, &local_err);
I'm not sure this call has any effect:
if (!(bs->open_flags & BDRV_O_INACTIVE)) {
return;
}
Is BDRV_O_INACTIVE set?
On 2017/5/12 3:15, Stefan Hajnoczi wrote:
> On Wed, Apr 12, 2017 at 10:05:20PM +0800, zhanghailiang wrote:
>> @@ -612,6 +644,16 @@ static void replication_do_checkpoint(ReplicationState *rs, Error **errp)
>> error_propagate(errp, local_err);
>> break;
>> }
>> + } else {
>> + /*
>> + * For shared disk, we need to force SVM to re-read metadata
>> + * that is loaded in memory, or there will be inconsistent.
>> + */
>> + bdrv_invalidate_cache(s->secondary_disk->bs, &local_err);
> I'm not sure this call has any effect:
>
> if (!(bs->open_flags & BDRV_O_INACTIVE)) {
> return;
> }
>
> Is BDRV_O_INACTIVE set?
No, you are right, it does not take any effect. So should we set this flag for secondary_disk ?
Is it enough to set this flag only, or should we call bdrv_inactivate_recurse() ?
To be honest, i'm not quite familiar with this parts.
Thanks,
Hailiang
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