Provide API for the COR-filter insertion/removal.
Also, drop the filter child permissions for an inactive state when the
filter node is being removed.
Signed-off-by: Andrey Shinkevich <andrey.shinkev...@virtuozzo.com>
---
block/copy-on-read.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 98 insertions(+)
diff --git a/block/copy-on-read.c b/block/copy-on-read.c
index 4030d56..31e1619 100644
--- a/block/copy-on-read.c
+++ b/block/copy-on-read.c
@@ -24,8 +24,15 @@
#include "qemu/cutils.h"
#include "block/block_int.h"
#include "qemu/module.h"
+#include "qapi/error.h"
+#include "qapi/qmp/qdict.h"
+#include "block/copy-on-read.h"
+typedef struct BDRVStateCOR {
+ bool active;
+} BDRVStateCOR;
+
static int cor_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
@@ -57,6 +64,17 @@ static void cor_child_perm(BlockDriverState *bs, BdrvChild
*c,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
+ BDRVStateCOR *s = bs->opaque;
+
+ if (!s->active) {
+ /*
+ * While the filter is being removed
+ */
+ *nperm = 0;
+ *nshared = BLK_PERM_ALL;
+ return;
+ }
+
*nperm = perm & PERM_PASSTHROUGH;
*nshared = (shared & PERM_PASSTHROUGH) | PERM_UNCHANGED;
@@ -150,6 +168,7 @@ static int cor_change_backing_file(BlockDriverState *bs,
static BlockDriver bdrv_copy_on_read = {
.format_name = "copy-on-read",
+ .instance_size = sizeof(BDRVStateCOR),
.bdrv_open = cor_open,
.bdrv_child_perm = cor_child_perm,
@@ -178,4 +197,83 @@ static void bdrv_copy_on_read_init(void)
bdrv_register(&bdrv_copy_on_read);
}
+
+static BlockDriverState *create_filter_node(BlockDriverState *bs,
+ const char *filter_node_name,
+ Error **errp)
+{
+ QDict *opts = qdict_new();
+
+ qdict_put_str(opts, "driver", "copy-on-read");
+ qdict_put_str(opts, "file", bdrv_get_node_name(bs));
+ if (filter_node_name) {
+ qdict_put_str(opts, "node-name", filter_node_name);
+ }
+
+ return bdrv_open(NULL, NULL, opts, BDRV_O_RDWR, errp);
+}
+
+
+BlockDriverState *bdrv_cor_filter_append(BlockDriverState *bs,
+ const char *filter_node_name,
+ Error **errp)
+{
+ BlockDriverState *cor_filter_bs;
+ BDRVStateCOR *state;
+ Error *local_err = NULL;
+
+ cor_filter_bs = create_filter_node(bs, filter_node_name, errp);
+ if (cor_filter_bs == NULL) {
+ error_prepend(errp, "Could not create filter node: ");
+ return NULL;
+ }
+
+ if (!filter_node_name) {
+ cor_filter_bs->implicit = true;
+ }
+
+ bdrv_drained_begin(bs);
+ bdrv_replace_node(bs, cor_filter_bs, &local_err);
+ bdrv_drained_end(bs);
+
+ if (local_err) {
+ bdrv_unref(cor_filter_bs);
+ error_propagate(errp, local_err);
+ return NULL;
+ }
+
+ state = cor_filter_bs->opaque;
+ state->active = true;
+
+ return cor_filter_bs;
+}
+
+
+void bdrv_cor_filter_drop(BlockDriverState *cor_filter_bs)
+{
+ BdrvChild *child;
+ BlockDriverState *bs;
+ BDRVStateCOR *s = cor_filter_bs->opaque;
+
+ child = bdrv_filtered_rw_child(cor_filter_bs);
+ if (!child) {
+ return;
+ }
+ bs = child->bs;
+
+ /* Retain the BDS until we complete the graph change. */
+ bdrv_ref(bs);
+ /* Hold a guest back from writing while permissions are being reset. */
+ bdrv_drained_begin(bs);
+ /* Drop permissions before the graph change. */
+ s->active = false;
+ bdrv_child_refresh_perms(cor_filter_bs, child, &error_abort);
+ bdrv_replace_node(cor_filter_bs, bs, &error_abort);
+
+ bdrv_drained_end(bs);
+ bdrv_unref(bs);
+ bdrv_unref(cor_filter_bs);
+}
+
+
block_init(bdrv_copy_on_read_init);
--
1.8.3.1
