On Tue, Nov 26, 2013 at 01:38:32AM -0500, Xu Wang wrote:
> Backing file loop should be checked before calling change_backing_
> file(). If loop appeared, this calling should be stopped and an
> error printed.
>
> Signed-off-by: Xu Wang <gesa...@linux.vnet.ibm.com>
> ---
> block.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/block.c b/block.c
> index b8cea1c..87f7018 100644
> --- a/block.c
> +++ b/block.c
> @@ -2075,6 +2075,7 @@ static void coroutine_fn
> wait_for_overlapping_requests(BlockDriverState *bs,
> * Return values:
> * 0 - success
> * -EINVAL - backing format specified, but no file
> + * -EIO - generic I/O error (may happen for all errors)
> * -ENOSPC - can't update the backing file because no space is left in the
> * image file header
> * -ENOTSUP - format driver doesn't support changing the backing file
> @@ -2083,6 +2084,7 @@ int bdrv_change_backing_file(BlockDriverState *bs,
> const char *backing_file, const char *backing_fmt)
> {
> BlockDriver *drv = bs->drv;
> + Error *local_err = NULL;
> int ret;
>
> /* Backing file format doesn't make sense without a backing file */
> @@ -2090,6 +2092,13 @@ int bdrv_change_backing_file(BlockDriverState *bs,
> return -EINVAL;
> }
>
> + /* Check if loop exists in backing files chain after change */
> + if (!bdrv_backing_chain_okay(backing_file, NULL, bs->filename,
> + &local_err)) {
> + error_report("Backing file check: %s", error_get_pretty(local_err));
You need to free local_err before returning (i.e.
error_free(local_err)).
> + return -EIO;
> + }
> +
> if (drv->bdrv_change_backing_file != NULL) {
> ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
> } else {
> --
> 1.8.1.4
>
>
