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Re: [PATCH v6 1/4] block/replication.c: Ignore requests after failover
From: |
Lukas Straub |
Subject: |
Re: [PATCH v6 1/4] block/replication.c: Ignore requests after failover |
Date: |
Wed, 23 Oct 2019 20:07:37 +0200 |
On Wed, 23 Oct 2019 14:49:29 +0200
Max Reitz <address@hidden> wrote:
> On 05.10.19 15:05, Lukas Straub wrote:
> > After failover the Secondary side of replication shouldn't change state,
> > because
> > it now functions as our primary disk.
> >
> > In replication_start, replication_do_checkpoint, replication_stop, ignore
> > the request if current state is BLOCK_REPLICATION_DONE (sucessful failover)
> > or
> > BLOCK_REPLICATION_FAILOVER (failover in progres i.e. currently merging
> > active
> > and hidden images into the base image).
> >
> > Signed-off-by: Lukas Straub <address@hidden>
> > Reviewed-by: Zhang Chen <address@hidden>
> > ---
> > block/replication.c | 38 +++++++++++++++++++++++++++++++++++---
> > 1 file changed, 35 insertions(+), 3 deletions(-)
>
> Disclaimer: I don’t know anything about the replication block driver.
>
> > diff --git a/block/replication.c b/block/replication.c
> > index 3d4dedddfc..97cc65c0cf 100644
> > --- a/block/replication.c
> > +++ b/block/replication.c
>
> [...]
>
> > @@ -529,8 +540,7 @@ static void replication_start(ReplicationState *rs,
> > ReplicationMode mode,
> > "Block device is in use by internal backup job");
> >
> > top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
> > - if (!top_bs || !bdrv_is_root_node(top_bs) ||
> > - !check_top_bs(top_bs, bs)) {
> > + if (!top_bs || !check_top_bs(top_bs, bs)) {
>
> It appears to me that top_bs is only used to install op blockers. It
> seems reasonable to require a root node to be able to do so (because op
> blockers are really only checked on a root node).
> (And the commit message doesn’t tell why we’d want to drop the
> is_root_node check here.)
>
> Now OTOH I don’t know whether the replication driver needs an op blocker
> at all or whether the permission system suffices...
Hi,
Now that I look at again, it actually works without this change, by passing
a correct top-id= parameter to the driver (I somehow overlooked that
parameter).
So I will revert this change in the next version.
>
> I suppose the rest of this patch is not really about the block layer, so
> I can’t really comment on it. (It looks OK to me from a generic and
> naïve standpoint, though.)
>
> > error_setg(errp, "No top_bs or it is invalid");
> > reopen_backing_file(bs, false, NULL);
> > aio_context_release(aio_context);
>
> [...]
>
> > @@ -593,7 +614,7 @@ static void replication_get_error(ReplicationState *rs,
> > Error **errp)
> > aio_context_acquire(aio_context);
> > s = bs->opaque;
> >
> > - if (s->stage != BLOCK_REPLICATION_RUNNING) {
> > + if (s->stage == BLOCK_REPLICATION_NONE) {
>
> Just one question out of curiosity, though: Is this a bug fix?
No, It only applies to continuous replication, because colo will
check all replication nodes for errors before checkpointing. So
a secondary continuing replication would error out here, because
it is either in state BLOCK_REPLICATION_DONE or
BLOCK_REPLICATION_FAILOVER.
> Max
>
> > error_setg(errp, "Block replication is not running");
> > aio_context_release(aio_context);
> > return;
>
- [PATCH v6 0/4] colo: Add support for continuous replication, Lukas Straub, 2019/10/05
- [PATCH v6 2/4] tests/test-replication.c: Add test for for secondary node continuing replication, Lukas Straub, 2019/10/05
- [PATCH v6 1/4] block/replication.c: Ignore requests after failover, Lukas Straub, 2019/10/05
- [PATCH v6 4/4] colo: Update Documentation for continuous replication, Lukas Straub, 2019/10/05
- RE: [PATCH v6 4/4] colo: Update Documentation for continuous replication, Zhang, Chen, 2019/10/09
- Re: [PATCH v6 4/4] colo: Update Documentation for continuous replication, Lukas Straub, 2019/10/09
- RE: [PATCH v6 4/4] colo: Update Documentation for continuous replication, Zhang, Chen, 2019/10/10
- Re: [PATCH v6 4/4] colo: Update Documentation for continuous replication, Lukas Straub, 2019/10/11
- RE: [PATCH v6 4/4] colo: Update Documentation for continuous replication, Zhang, Chen, 2019/10/11
[PATCH v6 3/4] net/filter.c: Add Options to insert filters anywhere in the filter list, Lukas Straub, 2019/10/05