qcow2: Use intermediate helper CB for amend
If there is more than one time-consuming operation to be performed for
qcow2_amend_options(), we need an intermediate CB which coordinates the
progress of the individual operations and passes the result to the
original status callback.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block/qcow2.c b/block/qcow2.c
index 07a4f0b..851de25 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2933,6 +2933,75 @@
return 0;
}
+typedef enum Qcow2AmendOperation {
+ /* This is the value Qcow2AmendHelperCBInfo::last_operation will be
+ * statically initialized to so that the helper CB can discern the first
+ * invocation from an operation change */
+ QCOW2_NO_OPERATION = 0,
+
+ QCOW2_DOWNGRADING,
+} Qcow2AmendOperation;
+
+typedef struct Qcow2AmendHelperCBInfo {
+ /* The code coordinating the amend operations should only modify
+ * these four fields; the rest will be managed by the CB */
+ BlockDriverAmendStatusCB *original_status_cb;
+ void *original_cb_opaque;
+
+ Qcow2AmendOperation current_operation;
+
+ /* Total number of operations to perform (only set once) */
+ int total_operations;
+
+ /* The following fields are managed by the CB */
+
+ /* Number of operations completed */
+ int operations_completed;
+
+ /* Cumulative offset of all completed operations */
+ int64_t offset_completed;
+
+ Qcow2AmendOperation last_operation;
+ int64_t last_work_size;
+} Qcow2AmendHelperCBInfo;
+
+static void qcow2_amend_helper_cb(BlockDriverState *bs,
+ int64_t operation_offset,
+ int64_t operation_work_size, void *opaque)
+{
+ Qcow2AmendHelperCBInfo *info = opaque;
+ int64_t current_work_size;
+ int64_t projected_work_size;
+
+ if (info->current_operation != info->last_operation) {
+ if (info->last_operation != QCOW2_NO_OPERATION) {
+ info->offset_completed += info->last_work_size;
+ info->operations_completed++;
+ }
+
+ info->last_operation = info->current_operation;
+ }
+
+ assert(info->total_operations > 0);
+ assert(info->operations_completed < info->total_operations);
+
+ info->last_work_size = operation_work_size;
+
+ current_work_size = info->offset_completed + operation_work_size;
+
+ /* current_work_size is the total work size for (operations_completed + 1)
+ * operations (which includes this one), so multiply it by the number of
+ * operations not covered and divide it by the number of operations
+ * covered to get a projection for the operations not covered */
+ projected_work_size = current_work_size * (info->total_operations -
+ info->operations_completed - 1)
+ / (info->operations_completed + 1);
+
+ info->original_status_cb(bs, info->offset_completed + operation_offset,
+ current_work_size + projected_work_size,
+ info->original_cb_opaque);
+}
+
static int qcow2_amend_options(BlockDriverState *bs, QemuOpts *opts,
BlockDriverAmendStatusCB *status_cb,
void *cb_opaque)
@@ -2947,6 +3016,7 @@
bool encrypt;
int ret;
QemuOptDesc *desc = opts->list->desc;
+ Qcow2AmendHelperCBInfo helper_cb_info;
while (desc && desc->name) {
if (!qemu_opt_find(opts, desc->name)) {
@@ -3006,6 +3076,12 @@
desc++;
}
+ helper_cb_info = (Qcow2AmendHelperCBInfo){
+ .original_status_cb = status_cb,
+ .original_cb_opaque = cb_opaque,
+ .total_operations = (new_version < old_version)
+ };
+
/* Upgrade first (some features may require compat=1.1) */
if (new_version > old_version) {
s->qcow_version = new_version;
@@ -3065,7 +3141,9 @@
/* Downgrade last (so unsupported features can be removed before) */
if (new_version < old_version) {
- ret = qcow2_downgrade(bs, new_version, status_cb, cb_opaque);
+ helper_cb_info.current_operation = QCOW2_DOWNGRADING;
+ ret = qcow2_downgrade(bs, new_version, &qcow2_amend_helper_cb,
+ &helper_cb_info);
if (ret < 0) {
return ret;
}
