On 2013年12月03日 21:26, Benoît Canet wrote:
---
block.c | 64 +++++++++++++++++++++++++++++++++++++++++------
block/blkverify.c | 2 +-
include/block/block.h | 16 +++++++++---
include/block/block_int.h | 9 ++++---
4 files changed, 75 insertions(+), 16 deletions(-)
diff --git a/block.c b/block.c
index 8016ff2..0569cb2 100644
--- a/block.c
+++ b/block.c
@@ -4945,21 +4945,69 @@ int bdrv_amend_options(BlockDriverState *bs,
QEMUOptionParameter *options)
return bs->drv->bdrv_amend_options(bs, options);
}
-ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *bs)
+/* will be used to recurse on single child block filter until first format
+ * (single child block filter will store their child in bs->file)
+ */
+ExtSnapshotPerm bdrv_generic_check_ext_snapshot(BlockDriverState *bs,
+ BlockDriverState *candidate)
{
- if (bs->drv->bdrv_check_ext_snapshot) {
- return bs->drv->bdrv_check_ext_snapshot(bs);
+ if (!bs->drv) {
+ return EXT_SNAPSHOT_FORBIDDEN;
}
- 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_CANT_SNAPSHOT]) {
This double negative feels hard to read for me.
+ if (bs == candidate) {
+ return EXT_SNAPSHOT_ALLOWED;
+ } else {
+ return EXT_SNAPSHOT_FORBIDDEN;
+ }
}
- /* external snapshots are allowed by default */
- return EXT_SNAPSHOT_ALLOWED;
+ if (!bs->drv->authorizations[BS_FILTER_PASS_DOWN]) {
+ return EXT_SNAPSHOT_FORBIDDEN;
+ }
+
+ if (!bs->file) {
+ return EXT_SNAPSHOT_FORBIDDEN;
+ }
+
+ return bdrv_recurse_check_ext_snapshot(bs->file, candidate);
}
-ExtSnapshotPerm bdrv_check_ext_snapshot_forbidden(BlockDriverState *bs)
+ExtSnapshotPerm bdrv_recurse_check_ext_snapshot(BlockDriverState *bs,
+ BlockDriverState *candidate)
{
+ if (bs->drv && bs->drv->bdrv_check_ext_snapshot) {
+ return bs->drv->bdrv_check_ext_snapshot(bs, candidate);
+ }
Maybe I'm missing something, but if a driver always returns positive
permit, despite of what candidate is (or even it's relevant to bs),
then doesn't it also affect other devices? because...
+
+ return bdrv_generic_check_ext_snapshot(bs, candidate);
+}
+
+/* This function check if the candidate bs has snapshots authorized by going
+ * down the forest of bs, skipping filters and stopping on the the first bses
+ * authorizing snapshots
+ */
+ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *candidate)
+{
+ BlockDriverState *bs;
+
+ /* walk down the bs forest recursively */
+ QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
this iterates through all the known graph trees (device_list),
instead of limiting to only the device that candidate belongs to.