Re: [Qemu-devel] [PATCH 47/54] migration/block: Use real permissions

[Max Reitz]

On 21.02.2017 15:58, Kevin Wolf wrote:
> Request BLK_PERM_CONSISTENT_READ for the source of block migration, and
> handle potential permission errors as good as we can in this place
> (which is not very good, but it matches the other failure cases).
> 
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
>  migration/block.c | 21 ++++++++++++++++-----
>  1 file changed, 16 insertions(+), 5 deletions(-)
> 
> diff --git a/migration/block.c b/migration/block.c
> index d259936..958d0fc 100644
> --- a/migration/block.c
> +++ b/migration/block.c
> @@ -379,7 +379,7 @@ static void unset_dirty_tracking(void)
>      }
>  }
>  
> -static void init_blk_migration(QEMUFile *f)
> +static int init_blk_migration(QEMUFile *f)
>  {
>      BlockDriverState *bs;
>      BlkMigDevState *bmds;
> @@ -390,6 +390,8 @@ static void init_blk_migration(QEMUFile *f)
>          BlkMigDevState *bmds;
>          BlockDriverState *bs;
>      } *bmds_bs;
> +    Error *local_err = NULL;
> +    int ret;
>  
>      block_mig_state.submitted = 0;
>      block_mig_state.read_done = 0;
> @@ -411,12 +413,12 @@ static void init_blk_migration(QEMUFile *f)
>  
>          sectors = bdrv_nb_sectors(bs);
>          if (sectors <= 0) {
> +            ret = sectors;
>              goto out;
>          }
>  
>          bmds = g_new0(BlkMigDevState, 1);
> -        /* FIXME Use real permissions */
> -        bmds->blk = blk_new(0, BLK_PERM_ALL);
> +        bmds->blk = blk_new(BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL);
>          bmds->blk_name = g_strdup(bdrv_get_device_name(bs));
>          bmds->bulk_completed = 0;
>          bmds->total_sectors = sectors;
> @@ -446,7 +448,11 @@ static void init_blk_migration(QEMUFile *f)
>          BlockDriverState *bs = bmds_bs[i].bs;
>  
>          if (bmds) {
> -            blk_insert_bs(bmds->blk, bs, &error_abort);
> +            ret = blk_insert_bs(bmds->blk, bs, &local_err);
> +            if (ret < 0) {
> +                error_report_err(local_err);
> +                goto out;
> +            }
>  
>              alloc_aio_bitmap(bmds);
>              error_setg(&bmds->blocker, "block device is in use by 
> migration");
> @@ -454,8 +460,10 @@ static void init_blk_migration(QEMUFile *f)
>          }
>      }
>  
> +    ret = 0;
>  out:
>      g_free(bmds_bs);
> +    return ret;
>  }
>  
>  /* Called with no lock taken.  */
> @@ -706,7 +714,10 @@ static int block_save_setup(QEMUFile *f, void *opaque)
>              block_mig_state.submitted, block_mig_state.transferred);
>  
>      qemu_mutex_lock_iothread();
> -    init_blk_migration(f);
> +    ret = init_blk_migration(f);
> +    if (ret < 0) {

What about qemu_mutex_unlock_iothread()?

Max

> +        return ret;
> +    }
>  
>      /* start track dirty blocks */
>      ret = set_dirty_tracking();
>

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