12:43 p.m.
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.shinkevich(a)virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com>
---
block/copy-on-read.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++++
block/copy-on-read.h | 35 +++++++++++++++++++++
2 files changed, 123 insertions(+)
create mode 100644 block/copy-on-read.h
diff --git a/block/copy-on-read.c b/block/copy-on-read.c
index cb03e0f..bcccf0f 100644
--- a/block/copy-on-read.c
+++ b/block/copy-on-read.c
@@ -23,11 +23,21 @@
#include "qemu/osdep.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)
{
+ BDRVStateCOR *state = bs->opaque;
+
bs->file = bdrv_open_child(NULL, options, "file", bs,
&child_of_bds,
BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
false, errp);
@@ -42,6 +52,13 @@ static int cor_open(BlockDriverState *bs, QDict *options, int flags,
((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) &
bs->file->bs->supported_zero_flags);
+ state->active = true;
+
+ /*
+ * We don't need to call bdrv_child_refresh_perms() now as the permissions
+ * will be updated later when the filter node gets its parent.
+ */
+
return 0;
}
@@ -57,6 +74,17 @@ 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;
@@ -135,6 +163,7 @@ static void cor_lock_medium(BlockDriverState *bs, bool locked)
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,
@@ -159,4 +188,63 @@ static void bdrv_copy_on_read_init(void)
bdrv_register(&bdrv_copy_on_read);
}
+
+BlockDriverState *bdrv_cor_filter_append(BlockDriverState *bs,
+ QDict *node_options,
+ int flags, Error **errp)
+{
+ BlockDriverState *cor_filter_bs;
+ Error *local_err = NULL;
+
+ cor_filter_bs = bdrv_open(NULL, NULL, node_options, flags, errp);
+ if (cor_filter_bs == NULL) {
+ error_prepend(errp, "Could not create COR-filter node: ");
+ return NULL;
+ }
+
+ if (!qdict_get_try_str(node_options, "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;
+ }
+
+ 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_filter_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);
diff --git a/block/copy-on-read.h b/block/copy-on-read.h
new file mode 100644
index 0000000..d6f2422
--- /dev/null
+++ b/block/copy-on-read.h
@@ -0,0 +1,35 @@
+/*
+ * Copy-on-read filter block driver
+ *
+ * The filter driver performs Copy-On-Read (COR) operations
+ *
+ * Copyright (c) 2018-2020 Virtuozzo International GmbH.
+ *
+ * Author:
+ * Andrey Shinkevich <andrey.shinkevich(a)virtuozzo.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>;.
+ */
+
+#ifndef BLOCK_COPY_ON_READ
+#define BLOCK_COPY_ON_READ
+
+#include "block/block_int.h"
+
+BlockDriverState *bdrv_cor_filter_append(BlockDriverState *bs,
+ QDict *node_options,
+ int flags, Error **errp);
+void bdrv_cor_filter_drop(BlockDriverState *cor_filter_bs);
+
+#endif /* BLOCK_COPY_ON_READ */
--
1.8.3.1