block/backup.c currently uses before write notifiers on the targeted
node. We can create a filter node instead to intercept write requests
for the backup job on the BDS level, instead of the BlockBackend level.
Signed-off-by: Manos Pitsidianakis
---
block.c| 89 +--
block/backup.c | 207 -
block/io.c | 10 +--
block/mirror.c | 4 +-
blockdev.c | 2 +-
include/block/block.h | 8 +-
tests/qemu-iotests/141.out | 2 +-
7 files changed, 277 insertions(+), 45 deletions(-)
diff --git a/block.c b/block.c
index 2de1c29eb3..81bd51b670 100644
--- a/block.c
+++ b/block.c
@@ -2088,6 +2088,38 @@ static void bdrv_parent_cb_resize(BlockDriverState *bs)
}
/*
+ * Sets the file link of a BDS. A new reference is created; callers
+ * which don't need their own reference any more must call bdrv_unref().
+ */
+void bdrv_set_file(BlockDriverState *bs, BlockDriverState *file_bs,
+ Error **errp)
+{
+if (file_bs) {
+bdrv_ref(file_bs);
+}
+
+if (bs->file) {
+bdrv_unref_child(bs, bs->file);
+}
+
+if (!file_bs) {
+bs->file = NULL;
+goto out;
+}
+
+bs->file = bdrv_attach_child(bs, file_bs, "file", &child_file,
+ errp);
+if (!bs->file) {
+bdrv_unref(file_bs);
+}
+
+bdrv_refresh_filename(bs);
+
+out:
+bdrv_refresh_limits(bs, NULL);
+}
+
+/*
* Sets the backing file link of a BDS. A new reference is created; callers
* which don't need their own reference any more must call bdrv_unref().
*/
@@ -2355,12 +2387,12 @@ static BlockDriverState
*bdrv_append_temp_snapshot(BlockDriverState *bs,
goto out;
}
-/* bdrv_append() consumes a strong reference to bs_snapshot
+/* bdrv_append_backing() consumes a strong reference to bs_snapshot
* (i.e. it will call bdrv_unref() on it) even on error, so in
* order to be able to return one, we have to increase
* bs_snapshot's refcount here */
bdrv_ref(bs_snapshot);
-bdrv_append(bs_snapshot, bs, &local_err);
+bdrv_append_backing(bs_snapshot, bs, &local_err);
if (local_err) {
error_propagate(errp, local_err);
bs_snapshot = NULL;
@@ -3142,7 +3174,7 @@ static bool should_update_child(BdrvChild *c,
BlockDriverState *to)
return false;
}
-if (c->role == &child_backing) {
+if (c->role == &child_backing || c->role == &child_file) {
/* If @from is a backing file of @to, ignore the child to avoid
* creating a loop. We only want to change the pointer of other
* parents. */
@@ -3213,6 +3245,45 @@ out:
}
/*
+ * Add new bs node at the top of a BDS chain while the chain is
+ * live, while keeping required fields on the top layer.
+ *
+ * This will modify the BlockDriverState fields, and swap contents
+ * between bs_new and bs_top. Both bs_new and bs_top are modified.
+ *
+ * bs_new must not be attached to a BlockBackend.
+ *
+ * bdrv_append_file() takes ownership of a bs_new reference and unrefs it
+ * because that's what the callers commonly need. bs_new will be referenced by
+ * the old parents of bs_top after bdrv_append_file() returns. If the caller
+ * needs to keep a reference of its own, it must call bdrv_ref().
+ */
+void bdrv_append_file(BlockDriverState *bs_new, BlockDriverState *bs_top,
+ Error **errp)
+{
+Error *local_err = NULL;
+
+bdrv_ref(bs_top);
+bdrv_set_file(bs_new, bs_top, &local_err);
+if (local_err) {
+error_propagate(errp, local_err);
+bdrv_set_file(bs_new, NULL, &error_abort);
+goto out;
+}
+bdrv_replace_node(bs_top, bs_new, &local_err);
+if (local_err) {
+error_propagate(errp, local_err);
+goto out;
+}
+
+/* bs_new is now referenced by its new parents, we don't need the
+ * additional reference any more. */
+out:
+bdrv_unref(bs_top);
+bdrv_unref(bs_new);
+}
+
+/*
* Add new bs contents at the top of an image chain while the chain is
* live, while keeping required fields on the top layer.
*
@@ -3223,13 +3294,13 @@ out:
*
* This function does not create any image files.
*
- * bdrv_append() takes ownership of a bs_new reference and unrefs it because
- * that's what the callers commonly need. bs_new will be referenced by the old
- * parents of bs_top after bdrv_append() returns. If the caller needs to keep a
- * reference of its own, it must call bdrv_ref().
+ * bdrv_append_backing() takes ownership of a bs_new reference and unrefs it
+ * because that's what the callers commonly need. bs_new will be referenced by
+ * the old parents of bs_top after bdrv_append_backing() returns. If the caller
+ * needs to keep a reference of its own, it must call bdrv_ref().
*/
-void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
- Error **errp)
