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block: Add "drained begin/end" for transactional external snapshot 

This ensures the atomicity of the transaction by avoiding processing of
external requests such as those from ioeventfd.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Fam Zheng 2015-10-23 11:08:10 +08:00 committed by Kevin Wolf
parent 51288d7917
commit da763e8301
1 changed files with 9 additions and 2 deletions
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11
blockdev.c
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@ -1569,6 +1569,7 @@ static void external_snapshot_prepare(BlkTransactionState *common,
/* Acquire AioContext now so any threads operating on old_bs stop */
state->aio_context = bdrv_get_aio_context(state->old_bs);
aio_context_acquire(state->aio_context);
bdrv_drained_begin(state->old_bs);
if (!bdrv_is_inserted(state->old_bs)) {
error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, device);
@ -1638,8 +1639,6 @@ static void external_snapshot_commit(BlkTransactionState *common)
* don't want to abort all of them if one of them fails the reopen */
bdrv_reopen(state->old_bs, state->old_bs->open_flags & ~BDRV_O_RDWR,
NULL);
aio_context_release(state->aio_context);
}
static void external_snapshot_abort(BlkTransactionState *common)
@ -1649,7 +1648,14 @@ static void external_snapshot_abort(BlkTransactionState *common)
if (state->new_bs) {
bdrv_unref(state->new_bs);
}
}
static void external_snapshot_clean(BlkTransactionState *common)
{
ExternalSnapshotState *state =
DO_UPCAST(ExternalSnapshotState, common, common);
if (state->aio_context) {
bdrv_drained_end(state->old_bs);
aio_context_release(state->aio_context);
}
}
@ -1809,6 +1815,7 @@ static const BdrvActionOps actions[] = {
.prepare = external_snapshot_prepare,
.commit = external_snapshot_commit,
.abort = external_snapshot_abort,
.clean = external_snapshot_clean,
},
[TRANSACTION_ACTION_KIND_DRIVE_BACKUP] = {
.instance_size = sizeof(DriveBackupState),