block: Create authorizations mechanism for external snapshot and resize.
Signed-off-by: Benoit Canet <benoit@irqsave.net>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block.c b/block.c
index 064df90..18c0a8d 100644
--- a/block.c
+++ b/block.c
@@ -5094,21 +5094,68 @@
return bs->drv->bdrv_amend_options(bs, options);
}
-ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *bs)
+/* Used to recurse on single child block filters.
+ * Single child block filter will store their child in bs->file.
+ */
+bool bdrv_generic_is_first_non_filter(BlockDriverState *bs,
+ BlockDriverState *candidate)
{
- if (bs->drv->bdrv_check_ext_snapshot) {
- return bs->drv->bdrv_check_ext_snapshot(bs);
+ if (!bs->drv) {
+ return false;
}
- if (bs->file && bs->file->drv && bs->file->drv->bdrv_check_ext_snapshot) {
- return bs->file->drv->bdrv_check_ext_snapshot(bs);
+ if (!bs->drv->authorizations[BS_IS_A_FILTER]) {
+ if (bs == candidate) {
+ return true;
+ } else {
+ return false;
+ }
}
- /* external snapshots are allowed by default */
- return EXT_SNAPSHOT_ALLOWED;
+ if (!bs->drv->authorizations[BS_FILTER_PASS_DOWN]) {
+ return false;
+ }
+
+ if (!bs->file) {
+ return false;
+ }
+
+ return bdrv_recurse_is_first_non_filter(bs->file, candidate);
}
-ExtSnapshotPerm bdrv_check_ext_snapshot_forbidden(BlockDriverState *bs)
+bool bdrv_recurse_is_first_non_filter(BlockDriverState *bs,
+ BlockDriverState *candidate)
{
- return EXT_SNAPSHOT_FORBIDDEN;
+ if (bs->drv && bs->drv->bdrv_recurse_is_first_non_filter) {
+ return bs->drv->bdrv_recurse_is_first_non_filter(bs, candidate);
+ }
+
+ return bdrv_generic_is_first_non_filter(bs, candidate);
+}
+
+/* This function checks if the candidate is the first non filter bs down it's
+ * bs chain. Since we don't have pointers to parents it explore all bs chains
+ * from the top. Some filters can choose not to pass down the recursion.
+ */
+bool bdrv_is_first_non_filter(BlockDriverState *candidate)
+{
+ BlockDriverState *bs;
+
+ /* walk down the bs forest recursively */
+ QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
+ bool perm;
+
+ if (!bs->file) {
+ continue;
+ }
+
+ perm = bdrv_recurse_is_first_non_filter(bs->file, candidate);
+
+ /* candidate is the first non filter */
+ if (perm) {
+ return true;
+ }
+ }
+
+ return false;
}