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Re: [Qemu-devel] [PATCH] migration: Fix block failure cases
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH] migration: Fix block failure cases |
Date: |
Thu, 1 Mar 2018 15:32:19 +0000 |
User-agent: |
Mutt/1.9.2 (2017-12-15) |
* Peter Xu (address@hidden) wrote:
> On Wed, Feb 28, 2018 at 04:49:37PM +0000, Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <address@hidden>
> >
> > This fixes a couple of cases where the block migration capability
> > doesn't get cleared when a migration failed.
> >
> > 1) When block migration is compiled out:
> > (qemu) migrate -d -b "exec:cat > /dev/null"
> > QEMU compiled without old-style (blk/-b, inc/-i) block migration
> > Use drive_mirror+NBD instead.
> > (qemu) migrate_set_capability xbzrle off
> > QEMU compiled without old-style (blk/-b, inc/-i) block migration
> > Use drive_mirror+NBD instead.
> >
> > This corresponds to https://bugzilla.redhat.com/show_bug.cgi?id=1550022
> >
> > 2) When a migration with a bad protocol is tried:
> > (qemu) migrate -d -b "foo:bah"
> > Parameter 'uri' expects a valid migration protocol
> > (qemu) info migrate_capabilities
> > xbzrle: off
> > rdma-pin-all: off
> > auto-converge: off
> > zero-blocks: off
> > compress: off
> > events: off
> > postcopy-ram: off
> > x-colo: off
> > release-ram: off
> > block: on <<<<<<-----
> > return-path: off
> > pause-before-switchover: off
> > x-multifd: off
> >
> > Fixes: 2833c59b947
> > Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> > ---
> > migration/migration.c | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/migration/migration.c b/migration/migration.c
> > index b913b98803..da0e4a1f56 100644
> > --- a/migration/migration.c
> > +++ b/migration/migration.c
> > @@ -1391,11 +1391,12 @@ void qmp_migrate(const char *uri, bool has_blk,
> > bool blk,
> > return;
> > }
> > migrate_set_block_enabled(true, &local_err);
> > + s->must_remove_block_options = true;
> > if (local_err) {
> > error_propagate(errp, local_err);
> > + block_cleanup_parameters(s);
> > return;
> > }
> > - s->must_remove_block_options = true;
> > }
> >
> > if (has_inc && inc) {
> > @@ -1417,11 +1418,10 @@ void qmp_migrate(const char *uri, bool has_blk,
> > bool blk,
> > } else if (strstart(uri, "fd:", &p)) {
> > fd_start_outgoing_migration(s, p, &local_err);
> > } else {
> > - error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "uri",
> > + error_setg(&local_err, QERR_INVALID_PARAMETER_VALUE, "uri",
> > "a valid migration protocol");
> > migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
> > MIGRATION_STATUS_FAILED);
> > - return;
> > }
> >
> > if (local_err) {
> > --
> > 2.14.3
> >
>
> Ouch...
>
> Instead it seems to be my fault in 4a84214ebe ("migration: provide
> migrate_caps_check()", 2017-07-18). For now I cannot understand why I
> did that before since it's obviously strange if without this
> squashed...
>
> diff --git a/migration/migration.c b/migration/migration.c
> index 0aa596f867..88ed9375aa 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -747,13 +747,15 @@ void
> qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
> {
> MigrationState *s = migrate_get_current();
> MigrationCapabilityStatusList *cap;
> + bool cap_list[MIGRATION_CAPABILITY__MAX];
>
> if (migration_is_setup_or_active(s->state)) {
> error_setg(errp, QERR_MIGRATION_ACTIVE);
> return;
> }
>
> - if (!migrate_caps_check(s->enabled_capabilities, params, errp)) {
> + memcpy(cap_list, s->enabled_capabilities, sizeof(cap_list));
> + if (!migrate_caps_check(cap_list, params, errp)) {
> return;
> }
>
> Otherwise I'll get:
>
> (qemu) migrate_set_capability postcopy-ram on
>
> (qemu) migrate_set_capability compress on
>
> Postcopy is not currently compatible with compression
>
> (qemu) info migrate_capabilities
> xbzrle: off
> rdma-pin-all: off
> auto-converge: off
> zero-blocks: off
> compress: on <------------------------- :(
> events: off
> postcopy-ram: on
> x-colo: off
> release-ram: off
> block: off
> return-path: off
> pause-before-switchover: off
> x-multifd: off
>
> And it looks very likely that this should solve the block bug too.
Yes, it looks like it should - but it doesn't solve the 2nd of my cases;
so we also need the 2nd half of my change.
> (So I think either I got a brain fart last July, or now...)
Of course it's the combination of two bugs :-)
Dave
> Thanks,
>
> --
> Peter Xu
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK