The command enables/disables copy-on-read mode for VM's disk while
VM is running.
This is needed when using external disk readers to shape access pattern
to the disk backend.
Signed-off-by: Denis Plotnikov <dplotni...@virtuozzo.com>
---
blockdev.c | 38 ++++++++++++++++++++++++++++++++++++++
qapi/block-core.json | 20 ++++++++++++++++++++
2 files changed, 58 insertions(+)
diff --git a/blockdev.c b/blockdev.c
index 4862323012..4a297dabef 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -4276,6 +4276,44 @@ out:
aio_context_release(aio_context);
}
+void qmp_block_set_copy_on_read(const char *device, bool enable, Error **errp)
+{
+ Error *local_err = NULL;
+ AioContext *aio_context;
+ BlockDriverState *bs = bdrv_lookup_bs(device, device, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ return;
+ }
+
+ aio_context = bdrv_get_aio_context(bs);
+ aio_context_acquire(aio_context);
+
+ if (enable) {
+ if (bs->open_flags & BDRV_O_COPY_ON_READ) {
+ error_setg(errp, "Can't enable copy-on-read for the device. "
+ "Copy-on-read is already enabled.");
+ } else {
+ if (bdrv_enable_copy_on_read(bs)) {
+ bs->open_flags |= BDRV_O_COPY_ON_READ;
+ } else {
+ error_setg(errp, "Can't enable copy-on-read. "
+ "The device is read-only.");
+ }
+ }
+ } else {
+ if (bs->open_flags & BDRV_O_COPY_ON_READ) {
+ bs->open_flags &= ~BDRV_O_COPY_ON_READ;
+ bdrv_disable_copy_on_read(bs);
+ } else {
+ error_setg(errp, "Can't disable copy-on-read for the device. "
+ "Copy-on-read is already disabled.");
+ }
+ }
+
+ aio_context_release(aio_context);
+}
+
static BdrvChild *bdrv_find_child(BlockDriverState *parent_bs,
const char *child_name)
{
diff --git a/qapi/block-core.json b/qapi/block-core.json
index fff23fc82b..7369a13009 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -4701,6 +4701,26 @@
{ 'command': 'block-set-write-threshold',
'data': { 'node-name': 'str', 'write-threshold': 'uint64' } }
+##
+# @block-set-copy-on-read:
+#
+# Enables and disables the copy-on-read property of a block device.
+#
+# @device: device or graph node name on which copy-on-read must be set.
+#
+# Since: 2.12
+#
+# Example:
+#
+# -> { "execute": "block-set-copy-on-read",
+# "arguments": { "device": "scsi0-0-0-0",
+# "enable": true } }
+# <- { "return": {} }
+#
+##
+{ 'command': 'block-set-copy-on-read',
+ 'data': { 'device': 'str', 'enable': 'bool' } }
+
##
# @x-blockdev-change:
#
--
2.17.0
