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));
+ 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
