Re: [Qemu-devel] [PATCH 6/6] migration: Pass Error ** argument to {save, load}_vmstate

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Juan Quintela (quintela@redhat.com) wrote:
> This way we use the "normal" way of printing errors for hmp commands.
> 
> --
> Paolo suggestion
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>

<snip>

> +int save_vmstate(const char *name, Error **errp)
>  {
>      BlockDriverState *bs, *bs1;
>      QEMUSnapshotInfo sn1, *sn = &sn1, old_sn1, *old_sn = &old_sn1;
> @@ -2076,29 +2076,27 @@ int save_vmstate(const char *name)
>      uint64_t vm_state_size;
>      qemu_timeval tv;
>      struct tm tm;
> -    Error *local_err = NULL;
>      AioContext *aio_context;
>  
>      if (!bdrv_all_can_snapshot(&bs)) {
> -        error_report("Device '%s' is writable but does not support snapshots",
> -                     bdrv_get_device_name(bs));
> +        error_setg(errp, "Device '%s' is writable but does not support "
> +                   "snapshots", bdrv_get_device_name(bs));
>          return ret;
>      }
>  
>      /* Delete old snapshots of the same name */
>      if (name) {
> -        ret = bdrv_all_delete_snapshot(name, &bs1, &local_err);
> +        ret = bdrv_all_delete_snapshot(name, &bs1, errp);
>          if (ret < 0) {
> -            error_reportf_err(local_err,
> -                              "Error while deleting snapshot on device '%s': ",
> -                              bdrv_get_device_name(bs1));
> +            error_prepend(errp, "Error while deleting snapshot on device "
> +                          "'%s': ", bdrv_get_device_name(bs1));

I thought the rule was that you had to use a local_err and use error_propagate?
(I hate that rule)

>              return ret;
>          }
>      }
>  
>      bs = bdrv_all_find_vmstate_bs();
>      if (bs == NULL) {
> -        error_report("No block device can accept snapshots");
> +        error_setg(errp, "No block device can accept snapshots");
>          return ret;
>      }
>      aio_context = bdrv_get_aio_context(bs);
> @@ -2107,7 +2105,7 @@ int save_vmstate(const char *name)
>  
>      ret = global_state_store();
>      if (ret) {
> -        error_report("Error saving global state");
> +        error_setg(errp, "Error saving global state");
>          return ret;
>      }
>      vm_stop(RUN_STATE_SAVE_VM);
> @@ -2139,21 +2137,20 @@ int save_vmstate(const char *name)
>      /* save the VM state */
>      f = qemu_fopen_bdrv(bs, 1);
>      if (!f) {
> -        error_report("Could not open VM state file");
> +        error_setg(errp, "Could not open VM state file");
>          goto the_end;
>      }
> -    ret = qemu_savevm_state(f, &local_err);
> +    ret = qemu_savevm_state(f, errp);
>      vm_state_size = qemu_ftell(f);
>      qemu_fclose(f);
>      if (ret < 0) {
> -        error_report_err(local_err);
>          goto the_end;
>      }
>  
>      ret = bdrv_all_create_snapshot(sn, bs, vm_state_size, &bs);
>      if (ret < 0) {
> -        error_report("Error while creating snapshot on '%s'",
> -                     bdrv_get_device_name(bs));
> +        error_setg(errp, "Error while creating snapshot on '%s'",
> +                   bdrv_get_device_name(bs));
>          goto the_end;
>      }
>  
> @@ -2226,7 +2223,7 @@ void qmp_xen_load_devices_state(const char *filename, Error **errp)
>      migration_incoming_state_destroy();
>  }
>  
> -int load_vmstate(const char *name)
> +int load_vmstate(const char *name, Error **errp)
>  {
>      BlockDriverState *bs, *bs_vm_state;
>      QEMUSnapshotInfo sn;
> @@ -2236,20 +2233,22 @@ int load_vmstate(const char *name)
>      MigrationIncomingState *mis = migration_incoming_get_current();
>  
>      if (!bdrv_all_can_snapshot(&bs)) {
> -        error_report("Device '%s' is writable but does not support snapshots",
> -                     bdrv_get_device_name(bs));
> +        error_setg(errp,
> +                   "Device '%s' is writable but does not support snapshots",
> +                   bdrv_get_device_name(bs));
>          return -ENOTSUP;
>      }
>      ret = bdrv_all_find_snapshot(name, &bs);
>      if (ret < 0) {
> -        error_report("Device '%s' does not have the requested snapshot '%s'",
> -                     bdrv_get_device_name(bs), name);
> +        error_setg(errp,
> +                   "Device '%s' does not have the requested snapshot '%s'",
> +                   bdrv_get_device_name(bs), name);
>          return ret;
>      }
>  
>      bs_vm_state = bdrv_all_find_vmstate_bs();
>      if (!bs_vm_state) {
> -        error_report("No block device supports snapshots");
> +        error_setg(errp, "No block device supports snapshots");
>          return -ENOTSUP;
>      }
>      aio_context = bdrv_get_aio_context(bs_vm_state);
> @@ -2261,8 +2260,8 @@ int load_vmstate(const char *name)
>      if (ret < 0) {
>          return ret;
>      } else if (sn.vm_state_size == 0) {
> -        error_report("This is a disk-only snapshot. Revert to it offline "
> -            "using qemu-img.");
> +        error_setg(errp, "This is a disk-only snapshot. Revert to it "
> +                   " offline using qemu-img");
>          return -EINVAL;
>      }
>  
> @@ -2271,7 +2270,7 @@ int load_vmstate(const char *name)
>  
>      ret = bdrv_all_goto_snapshot(name, &bs);
>      if (ret < 0) {
> -        error_report("Error %d while activating snapshot '%s' on '%s'",
> +        error_setg(errp, "Error %d while activating snapshot '%s' on '%s'",
>                       ret, name, bdrv_get_device_name(bs));
>          return ret;
>      }
> @@ -2279,7 +2278,7 @@ int load_vmstate(const char *name)
>      /* restore the VM state */
>      f = qemu_fopen_bdrv(bs_vm_state, 0);
>      if (!f) {
> -        error_report("Could not open VM state file");
> +        error_setg(errp, "Could not open VM state file");
>          return -EINVAL;
>      }
>  
> @@ -2293,7 +2292,7 @@ int load_vmstate(const char *name)
>  
>      migration_incoming_state_destroy();
>      if (ret < 0) {
> -        error_report("Error %d while loading VM state", ret);
> +        error_setg(errp, "Error %d while loading VM state", ret);
>          return ret;
>      }
>  
> diff --git a/replay/replay-snapshot.c b/replay/replay-snapshot.c
> index 8cced46..fdc4353 100644
> --- a/replay/replay-snapshot.c
> +++ b/replay/replay-snapshot.c
> @@ -62,14 +62,16 @@ void replay_vmstate_register(void)
>  
>  void replay_vmstate_init(void)
>  {
> +    Error *err = NULL;
> +
>      if (replay_snapshot) {
>          if (replay_mode == REPLAY_MODE_RECORD) {
> -            if (save_vmstate(replay_snapshot) != 0) {
> +            if (save_vmstate(replay_snapshot, &err) != 0) {
>                  error_report("Could not create snapshot for icount record");
>                  exit(1);
>              }
>          } else if (replay_mode == REPLAY_MODE_PLAY) {
> -            if (load_vmstate(replay_snapshot) != 0) {
> +            if (load_vmstate(replay_snapshot, &err) != 0) {
>                  error_report("Could not load snapshot for icount replay");
>                  exit(1);
>              }

How do either of the contents of the 'err' get reported - they're not
printed at all are they?
(I don't like error_abort, I'd rather see the other message as well).

Dave

> diff --git a/vl.c b/vl.c
> index 0b4ed52..8b3ec2e 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -4681,7 +4681,9 @@ int main(int argc, char **argv, char **envp)
>      if (replay_mode != REPLAY_MODE_NONE) {
>          replay_vmstate_init();
>      } else if (loadvm) {
> -        if (load_vmstate(loadvm) < 0) {
> +        Error *local_err = NULL;
> +        if (load_vmstate(loadvm, &local_err) < 0) {
> +            error_report_err(local_err);
>              autostart = 0;
>          }
>      }
> -- 
> 2.9.3
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK