Now qmp_transaction() can be extended with other operation, external snapshot or backing chain creation, is just one case it.
Signed-off-by: Wenchao Xia <[email protected]> --- blockdev.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++-------- 1 files changed, 58 insertions(+), 10 deletions(-) diff --git a/blockdev.c b/blockdev.c index 3e69569..9f0acfb 100644 --- a/blockdev.c +++ b/blockdev.c @@ -779,14 +779,35 @@ void qmp_blockdev_snapshot_sync(const char *device, const char *snapshot_file, /* New and old BlockDriverState structs for group snapshots */ + +/* Only in prepare() it may fail, so roll back just need to take care + what is done in prepare(). */ +typedef struct BdrvActionOps { + /* Prepare the work, must NOT be NULL. */ + int (*prepare)(BlockdevAction *action, void **p_opaque, Error **errp); + /* Commit the changes, can be NULL. */ + void (*commit)(BlockdevAction *action, void *opaque); + /* Rollback the changes on fail, mut NOT be NULL. */ + void (*rollback)(BlockdevAction *action, void *opaque); + /* Clean up resource in the end, can be NULL. */ + void (*clean)(BlockdevAction *action, void *opaque); +} BdrvActionOps; + typedef struct BlkTransactionStates { - BlockDriverState *old_bs; - BlockDriverState *new_bs; + BlockdevAction *action; + void *opaque; + const BdrvActionOps *ops; QSIMPLEQ_ENTRY(BlkTransactionStates) entry; } BlkTransactionStates; +/* external snapshot private data */ +typedef struct ExternalSnapshotState { + BlockDriverState *old_bs; + BlockDriverState *new_bs; +} ExternalSnapshotState; + static int external_snapshot_prepare(BlockdevAction *action, - BlkTransactionStates *states, + void **p_opaque, Error **errp) { BlockDriver *proto_drv; @@ -797,6 +818,7 @@ static int external_snapshot_prepare(BlockdevAction *action, const char *new_image_file; const char *format = "qcow2"; enum NewImageMode mode = NEW_IMAGE_MODE_ABSOLUTE_PATHS; + ExternalSnapshotState *states; /* get parameters */ g_assert(action->kind == BLOCKDEV_ACTION_KIND_BLOCKDEV_SNAPSHOT_SYNC); @@ -817,6 +839,9 @@ static int external_snapshot_prepare(BlockdevAction *action, goto fail; } + *p_opaque = g_malloc0(sizeof(ExternalSnapshotState)); + states = *p_opaque; + states->old_bs = bdrv_find(device); if (!states->old_bs) { error_set(errp, QERR_DEVICE_NOT_FOUND, device); @@ -878,8 +903,10 @@ static int external_snapshot_prepare(BlockdevAction *action, } static void external_snapshot_commit(BlockdevAction *action, - BlkTransactionStates *states) + void *opaque) { + ExternalSnapshotState *states = opaque; + /* 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 @@ -890,13 +917,27 @@ static void external_snapshot_commit(BlockdevAction *action, } static void external_snapshot_rollback(BlockdevAction *action, - BlkTransactionStates *states) + void *opaque) { + ExternalSnapshotState *states = opaque; if (states->new_bs) { bdrv_delete(states->new_bs); } } +static void external_snapshot_clean(BlockdevAction *action, + void *opaque) +{ + g_free(opaque); +} + +const BdrvActionOps external_snapshot_ops = { + .prepare = external_snapshot_prepare, + .commit = external_snapshot_commit, + .rollback = external_snapshot_rollback, + .clean = external_snapshot_clean, +}; + /* * '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 @@ -923,23 +964,27 @@ void qmp_transaction(BlockdevActionList *dev_list, Error **errp) states = g_malloc0(sizeof(BlkTransactionStates)); QSIMPLEQ_INSERT_TAIL(&snap_bdrv_states, states, entry); + states->action = dev_info; switch (dev_info->kind) { case BLOCKDEV_ACTION_KIND_BLOCKDEV_SNAPSHOT_SYNC: - if (external_snapshot_prepare(dev_info, states, errp)) { - goto delete_and_fail; - } + states->ops = &external_snapshot_ops; break; default: abort(); } + if (states->ops->prepare(states->action, &states->opaque, errp)) { + 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(NULL, states); + if (states->ops->commit) { + states->ops->commit(states->action, states->opaque); + } } /* success */ @@ -951,10 +996,13 @@ delete_and_fail: * the original bs for all images */ QSIMPLEQ_FOREACH(states, &snap_bdrv_states, entry) { - external_snapshot_rollback(NULL, states); + states->ops->rollback(states->action, states->opaque); } exit: QSIMPLEQ_FOREACH_SAFE(states, &snap_bdrv_states, entry, next) { + if (states->ops->clean) { + states->ops->clean(states->action, states->opaque); + } g_free(states); } } -- 1.7.1
