Re: [Qemu-devel] [PATCH v2] block: Add error handling to bdrv_invalidate_cache()

[Benoît Canet]

The Tuesday 18 Mar 2014 à 15:36:42 (+0100), Kevin Wolf wrote :
> If it returns an error, the migrated VM will not be started, but qemu
> exits with an error message.
> 
> Signed-off-by: Kevin Wolf <address@hidden>
> Reviewed-by: Juan Quintela <address@hidden>
> Reviewed-by: Eric Blake <address@hidden>
> ---
> 
> v2:
> - Update quorum as well (not built by default, so it escaped my
>   attention in v1)
> 
>  block.c                   | 28 ++++++++++++++++++++++------
>  block/qcow2.c             | 22 +++++++++++++++++++---
>  block/qed.c               | 21 ++++++++++++++++++---
>  block/quorum.c            |  9 +++++++--
>  include/block/block.h     |  4 ++--
>  include/block/block_int.h |  2 +-
>  migration.c               |  8 +++++++-
>  7 files changed, 76 insertions(+), 18 deletions(-)
> 
> diff --git a/block.c b/block.c
> index 53f5b44..acb70fd 100644
> --- a/block.c
> +++ b/block.c
> @@ -4781,27 +4781,43 @@ flush_parent:
>      return bdrv_co_flush(bs->file);
>  }
>  
> -void bdrv_invalidate_cache(BlockDriverState *bs)
> +void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp)
>  {
> +    Error *local_err = NULL;
> +    int ret;
> +
>      if (!bs->drv)  {
>          return;
>      }
>  
>      if (bs->drv->bdrv_invalidate_cache) {
> -        bs->drv->bdrv_invalidate_cache(bs);
> +        bs->drv->bdrv_invalidate_cache(bs, &local_err);
>      } else if (bs->file) {
> -        bdrv_invalidate_cache(bs->file);
> +        bdrv_invalidate_cache(bs->file, &local_err);
> +    }
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
>      }
>  
> -    refresh_total_sectors(bs, bs->total_sectors);
> +    ret = refresh_total_sectors(bs, bs->total_sectors);
> +    if (ret < 0) {
> +        error_setg_errno(errp, -ret, "Could not refresh total sector count");
> +        return;
> +    }
>  }
>  
> -void bdrv_invalidate_cache_all(void)
> +void bdrv_invalidate_cache_all(Error **errp)
>  {
>      BlockDriverState *bs;
> +    Error *local_err = NULL;
>  
>      QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
> -        bdrv_invalidate_cache(bs);
> +        bdrv_invalidate_cache(bs, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
> +        }
>      }
>  }
>  
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 945c9d6..b9dc960 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -1156,7 +1156,7 @@ static void qcow2_close(BlockDriverState *bs)
>      qcow2_free_snapshots(bs);
>  }
>  
> -static void qcow2_invalidate_cache(BlockDriverState *bs)
> +static void qcow2_invalidate_cache(BlockDriverState *bs, Error **errp)
>  {
>      BDRVQcowState *s = bs->opaque;
>      int flags = s->flags;
> @@ -1164,6 +1164,8 @@ static void qcow2_invalidate_cache(BlockDriverState *bs)
>      AES_KEY aes_decrypt_key;
>      uint32_t crypt_method = 0;
>      QDict *options;
> +    Error *local_err = NULL;
> +    int ret;
>  
>      /*
>       * Backing files are read-only which makes all of their metadata 
> immutable,
> @@ -1178,11 +1180,25 @@ static void qcow2_invalidate_cache(BlockDriverState 
> *bs)
>  
>      qcow2_close(bs);
>  
> -    bdrv_invalidate_cache(bs->file);
> +    bdrv_invalidate_cache(bs->file, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
> +    }
>  
>      memset(s, 0, sizeof(BDRVQcowState));
>      options = qdict_clone_shallow(bs->options);
> -    qcow2_open(bs, options, flags, NULL);
> +
> +    ret = qcow2_open(bs, options, flags, &local_err);
> +    if (local_err) {
> +        error_setg(errp, "Could not reopen qcow2 layer: %s",
> +                   error_get_pretty(local_err));
> +        error_free(local_err);
> +        return;
> +    } else if (ret < 0) {
> +        error_setg_errno(errp, -ret, "Could not reopen qcow2 layer");
> +        return;
> +    }
>  
>      QDECREF(options);
>  
> diff --git a/block/qed.c b/block/qed.c
> index 837accd..3bd9db9 100644
> --- a/block/qed.c
> +++ b/block/qed.c
> @@ -1558,16 +1558,31 @@ static int 
> bdrv_qed_change_backing_file(BlockDriverState *bs,
>      return ret;
>  }
>  
> -static void bdrv_qed_invalidate_cache(BlockDriverState *bs)
> +static void bdrv_qed_invalidate_cache(BlockDriverState *bs, Error **errp)
>  {
>      BDRVQEDState *s = bs->opaque;
> +    Error *local_err = NULL;
> +    int ret;
>  
>      bdrv_qed_close(bs);
>  
> -    bdrv_invalidate_cache(bs->file);
> +    bdrv_invalidate_cache(bs->file, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
> +    }
>  
>      memset(s, 0, sizeof(BDRVQEDState));
> -    bdrv_qed_open(bs, NULL, bs->open_flags, NULL);
> +    ret = bdrv_qed_open(bs, NULL, bs->open_flags, &local_err);
> +    if (local_err) {
> +        error_setg(errp, "Could not reopen qed layer: %s",
> +                   error_get_pretty(local_err));
> +        error_free(local_err);
> +        return;
> +    } else if (ret < 0) {
> +        error_setg_errno(errp, -ret, "Could not reopen qed layer");
> +        return;
> +    }
>  }
>  
>  static int bdrv_qed_check(BlockDriverState *bs, BdrvCheckResult *result,
> diff --git a/block/quorum.c b/block/quorum.c
> index 33bf2ae..7f580a8 100644
> --- a/block/quorum.c
> +++ b/block/quorum.c
> @@ -625,13 +625,18 @@ static int64_t quorum_getlength(BlockDriverState *bs)
>      return result;
>  }
>  
> -static void quorum_invalidate_cache(BlockDriverState *bs)
> +static void quorum_invalidate_cache(BlockDriverState *bs, Error **errp)
>  {
>      BDRVQuorumState *s = bs->opaque;
> +    Error *local_err = NULL;
>      int i;
>  
>      for (i = 0; i < s->num_children; i++) {
> -        bdrv_invalidate_cache(s->bs[i]);
> +        bdrv_invalidate_cache(s->bs[i], &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
> +        }
>      }
>  }
>  
> diff --git a/include/block/block.h b/include/block/block.h
> index bd34d14..1ed55d8 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -329,8 +329,8 @@ BlockDriverAIOCB *bdrv_aio_ioctl(BlockDriverState *bs,
>          BlockDriverCompletionFunc *cb, void *opaque);
>  
>  /* Invalidate any cached metadata used by image formats */
> -void bdrv_invalidate_cache(BlockDriverState *bs);
> -void bdrv_invalidate_cache_all(void);
> +void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp);
> +void bdrv_invalidate_cache_all(Error **errp);
>  
>  void bdrv_clear_incoming_migration_all(void);
>  
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 4fc5ea8..cd5bc73 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -153,7 +153,7 @@ struct BlockDriver {
>      /*
>       * Invalidate any cached meta-data.
>       */
> -    void (*bdrv_invalidate_cache)(BlockDriverState *bs);
> +    void (*bdrv_invalidate_cache)(BlockDriverState *bs, Error **errp);
>  
>      /*
>       * Flushes all data that was already written to the OS all the way down 
> to
> diff --git a/migration.c b/migration.c
> index 00f465e..e0e24d4 100644
> --- a/migration.c
> +++ b/migration.c
> @@ -101,6 +101,7 @@ void qemu_start_incoming_migration(const char *uri, Error 
> **errp)
>  static void process_incoming_migration_co(void *opaque)
>  {
>      QEMUFile *f = opaque;
> +    Error *local_err = NULL;
>      int ret;
>  
>      ret = qemu_loadvm_state(f);
> @@ -115,7 +116,12 @@ static void process_incoming_migration_co(void *opaque)
>  
>      bdrv_clear_incoming_migration_all();
>      /* Make sure all file formats flush their mutable metadata */
> -    bdrv_invalidate_cache_all();
> +    bdrv_invalidate_cache_all(&local_err);
> +    if (local_err) {
> +        qerror_report_err(local_err);
> +        error_free(local_err);
> +        exit(EXIT_FAILURE);
> +    }
>  
>      if (autostart) {
>          vm_start();
> -- 
> 1.8.3.1
> 

Look good

Reviewed-by: Benoit Canet <address@hidden>