From patchwork Thu May 2 02:26:46 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wayne Xia X-Patchwork-Id: 240886 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id D58002C00A4 for ; Thu, 2 May 2013 12:32:21 +1000 (EST) Received: from localhost ([::1]:56276 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UXjJk-0000Zx-3A for incoming@patchwork.ozlabs.org; Wed, 01 May 2013 22:32:20 -0400 Received: from eggs.gnu.org ([208.118.235.92]:53370) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UXjGI-0003fq-Iv for qemu-devel@nongnu.org; Wed, 01 May 2013 22:28:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UXjGG-0002q1-JC for qemu-devel@nongnu.org; Wed, 01 May 2013 22:28:46 -0400 Received: from e23smtp02.au.ibm.com ([202.81.31.144]:39671) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UXjGF-0002pY-I2 for qemu-devel@nongnu.org; Wed, 01 May 2013 22:28:44 -0400 Received: from /spool/local by e23smtp02.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Thu, 2 May 2013 12:20:33 +1000 Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [9.190.235.21]) by d23dlp01.au.ibm.com (Postfix) with ESMTP id 7ED9E2CE8051 for ; Thu, 2 May 2013 12:28:38 +1000 (EST) Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r422SVjE19726566 for ; Thu, 2 May 2013 12:28:31 +1000 Received: from d23av04.au.ibm.com (loopback [127.0.0.1]) by d23av04.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r422SbbJ011660 for ; Thu, 2 May 2013 12:28:37 +1000 Received: from RH63Wenchao (wenchaox.cn.ibm.com [9.115.122.225]) by d23av04.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id r422QrHM008158; Thu, 2 May 2013 12:28:36 +1000 From: Wenchao Xia To: qemu-devel@nongnu.org Date: Thu, 2 May 2013 10:26:46 +0800 Message-Id: <1367461606-7554-6-git-send-email-xiawenc@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1367461606-7554-1-git-send-email-xiawenc@linux.vnet.ibm.com> References: <1367461606-7554-1-git-send-email-xiawenc@linux.vnet.ibm.com> X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13050202-5490-0000-0000-0000036159F4 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.4.x-2.6.x [generic] X-Received-From: 202.81.31.144 Cc: kwolf@redhat.com, stefanha@gmail.com, dietmar@proxmox.com, pbonzini@redhat.com, Wenchao Xia Subject: [Qemu-devel] [PATCH V4 5/5] block: make all steps in qmp_transaction() as callback X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org 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 Reviewed-by: Eric Blake --- blockdev.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++------------- 1 files changed, 71 insertions(+), 21 deletions(-) diff --git a/blockdev.c b/blockdev.c index 77adec8..87ed99e 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 + rollback() 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); + /* Rollback the changes on fail, can be NULL. */ + void (*rollback)(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 parent 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_rollback(BlkTransactionStates *states) +static void external_snapshot_rollback(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, + .rollback = external_snapshot_rollback, + }, +}; + /* * '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 +955,31 @@ 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 +991,15 @@ delete_and_fail: * the original bs for all images */ QSIMPLEQ_FOREACH(states, &snap_bdrv_states, entry) { - external_snapshot_rollback(states); + if (states->ops->rollback) { + states->ops->rollback(states); + } } exit: QSIMPLEQ_FOREACH_SAFE(states, &snap_bdrv_states, entry, next) { + if (states->ops->clean) { + states->ops->clean(states); + } g_free(states); } }