From 2b05ad88980acb91357598f5ed041ec33aec0de6 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Mon, 9 Sep 2013 14:27:56 +0200
Subject: [PATCH 05/38] block: make all steps in qmp_transaction() as callback
RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <1378736903-18489-6-git-send-email-kwolf@redhat.com>
Patchwork-id: 54192
O-Subject: [RHEL-7.0 qemu-kvm PATCH 05/32] block: make all steps in qmp_transaction() as callback
Bugzilla: 1005818
RH-Acked-by: Fam Zheng <famz@redhat.com>
RH-Acked-by: Max Reitz <mreitz@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
From: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Bugzilla: 1005818
Make it easier to add other operations to qmp_transaction() by using
callbacks, with external snapshots serving as an example implementation
of the callbacks.
Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit ba0c86a34e29b31ef360feda74c94200a5403fdd)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
blockdev.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++----------------
1 file changed, 71 insertions(+), 24 deletions(-)
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
blockdev.c | 95 ++++++++++++++++++++++++++++++++++++++++++++---------------
1 files changed, 71 insertions(+), 24 deletions(-)
diff --git a/blockdev.c b/blockdev.c
index b040f0f..b8521c7 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -779,14 +779,43 @@ void qmp_blockdev_snapshot_sync(const char *device, const char *snapshot_file,
/* New and old BlockDriverState structs for group snapshots */
-typedef struct BlkTransactionStates {
+
+typedef struct BlkTransactionStates BlkTransactionStates;
+
+/* Only prepare() may fail. In a single transaction, only one of commit() or
+ abort() will be called, clean() will always be called if it present. */
+typedef struct BdrvActionOps {
+ /* Size of state struct, in bytes. */
+ size_t instance_size;
+ /* Prepare the work, must NOT be NULL. */
+ void (*prepare)(BlkTransactionStates *common, Error **errp);
+ /* Commit the changes, must NOT be NULL. */
+ void (*commit)(BlkTransactionStates *common);
+ /* Abort the changes on fail, can be NULL. */
+ void (*abort)(BlkTransactionStates *common);
+ /* Clean up resource in the end, can be NULL. */
+ void (*clean)(BlkTransactionStates *common);
+} BdrvActionOps;
+
+/*
+ * This structure must be arranged as first member in child type, assuming
+ * that compiler will also arrange it to the same address with parent instance.
+ * Later it will be used in free().
+ */
+struct BlkTransactionStates {
+ BlockdevAction *action;
+ const BdrvActionOps *ops;
+ QSIMPLEQ_ENTRY(BlkTransactionStates) entry;
+};
+
+/* external snapshot private data */
+typedef struct ExternalSnapshotStates {
+ BlkTransactionStates common;
BlockDriverState *old_bs;
BlockDriverState *new_bs;
- QSIMPLEQ_ENTRY(BlkTransactionStates) entry;
-} BlkTransactionStates;
+} ExternalSnapshotStates;
-static void external_snapshot_prepare(BlockdevAction *action,
- BlkTransactionStates *states,
+static void external_snapshot_prepare(BlkTransactionStates *common,
Error **errp)
{
BlockDriver *proto_drv;
@@ -797,6 +826,9 @@ static void external_snapshot_prepare(BlockdevAction *action,
const char *new_image_file;
const char *format = "qcow2";
enum NewImageMode mode = NEW_IMAGE_MODE_ABSOLUTE_PATHS;
+ ExternalSnapshotStates *states =
+ DO_UPCAST(ExternalSnapshotStates, common, common);
+ BlockdevAction *action = common->action;
/* get parameters */
g_assert(action->kind == BLOCKDEV_ACTION_KIND_BLOCKDEV_SNAPSHOT_SYNC);
@@ -871,8 +903,11 @@ static void external_snapshot_prepare(BlockdevAction *action,
}
}
-static void external_snapshot_commit(BlkTransactionStates *states)
+static void external_snapshot_commit(BlkTransactionStates *common)
{
+ ExternalSnapshotStates *states =
+ DO_UPCAST(ExternalSnapshotStates, common, common);
+
/* This removes our old bs from the bdrv_states, and adds the new bs */
bdrv_append(states->new_bs, states->old_bs);
/* We don't need (or want) to use the transactional
@@ -882,13 +917,24 @@ static void external_snapshot_commit(BlkTransactionStates *states)
NULL);
}
-static void external_snapshot_abort(BlkTransactionStates *states)
+static void external_snapshot_abort(BlkTransactionStates *common)
{
+ ExternalSnapshotStates *states =
+ DO_UPCAST(ExternalSnapshotStates, common, common);
if (states->new_bs) {
bdrv_delete(states->new_bs);
}
}
+static const BdrvActionOps actions[] = {
+ [BLOCKDEV_ACTION_KIND_BLOCKDEV_SNAPSHOT_SYNC] = {
+ .instance_size = sizeof(ExternalSnapshotStates),
+ .prepare = external_snapshot_prepare,
+ .commit = external_snapshot_commit,
+ .abort = external_snapshot_abort,
+ },
+};
+
/*
* 'Atomic' group snapshots. The snapshots are taken as a set, and if any fail
* then we do not pivot any of the devices in the group, and abandon the
@@ -909,32 +955,28 @@ void qmp_transaction(BlockdevActionList *dev_list, Error **errp)
/* We don't do anything in this loop that commits us to the snapshot */
while (NULL != dev_entry) {
BlockdevAction *dev_info = NULL;
+ const BdrvActionOps *ops;
dev_info = dev_entry->value;
dev_entry = dev_entry->next;
- states = g_malloc0(sizeof(BlkTransactionStates));
+ assert(dev_info->kind < ARRAY_SIZE(actions));
+
+ ops = &actions[dev_info->kind];
+ states = g_malloc0(ops->instance_size);
+ states->ops = ops;
+ states->action = dev_info;
QSIMPLEQ_INSERT_TAIL(&snap_bdrv_states, states, entry);
- switch (dev_info->kind) {
- case BLOCKDEV_ACTION_KIND_BLOCKDEV_SNAPSHOT_SYNC:
- external_snapshot_prepare(dev_info, states, errp);
- if (error_is_set(&local_err)) {
- error_propagate(errp, local_err);
- goto delete_and_fail;
- }
- break;
- default:
- abort();
+ states->ops->prepare(states, &local_err);
+ if (error_is_set(&local_err)) {
+ error_propagate(errp, local_err);
+ goto delete_and_fail;
}
-
}
-
- /* Now we are going to do the actual pivot. Everything up to this point
- * is reversible, but we are committed at this point */
QSIMPLEQ_FOREACH(states, &snap_bdrv_states, entry) {
- external_snapshot_commit(states);
+ states->ops->commit(states);
}
/* success */
@@ -946,10 +988,15 @@ delete_and_fail:
* the original bs for all images
*/
QSIMPLEQ_FOREACH(states, &snap_bdrv_states, entry) {
- external_snapshot_abort(states);
+ if (states->ops->abort) {
+ states->ops->abort(states);
+ }
}
exit:
QSIMPLEQ_FOREACH_SAFE(states, &snap_bdrv_states, entry, next) {
+ if (states->ops->clean) {
+ states->ops->clean(states);
+ }
g_free(states);
}
}
--
1.7.1