On 30.07.2015 08:39, Fam Zheng wrote:
Sometimes block jobs must execute as a transaction group. Finishing
jobs wait until all other jobs are ready to complete successfully.
Failure or cancellation of one job cancels the other jobs in the group.
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
[Rewrite the implementation which is now contained in block_job_completed.
--Fam]
Signed-off-by: Fam Zheng <f...@redhat.com>
---
blockjob.c | 115 ++++++++++++++++++++++++++++++++++++++++++++++-
include/block/block.h | 1 +
include/block/blockjob.h | 29 ++++++++++++
3 files changed, 143 insertions(+), 2 deletions(-)
diff --git a/blockjob.c b/blockjob.c
index 36c18e0..c78ad0a 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -36,6 +36,16 @@
#include "qemu/timer.h"
#include "qapi-event.h"
+/* Transactional group of block jobs */
+struct BlockJobTxn {
+
+ /* Is this txn being cancelled? */
+ bool aborting;
+
+ /* List of jobs */
+ QLIST_HEAD(, BlockJob) jobs;
+};
+
void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
int64_t speed, BlockCompletionFunc *cb,
void *opaque, Error **errp)
@@ -90,6 +100,83 @@ void block_job_unref(BlockJob *job)
}
}
+static void block_job_completed_single(BlockJob *job)
+{
+ if (!job->ret) {
+ if (job->driver->commit) {
+ job->driver->commit(job);
+ }
+ } else {
+ if (job->driver->abort) {
+ job->driver->abort(job);
+ }
+ }
+ job->cb(job->opaque, job->ret);
+ block_job_unref(job);
+}
+
+static void block_job_completed_txn_abort(BlockJob *job)
+{
+ AioContext *ctx;
+ BlockJobTxn *txn = job->txn;
+ BlockJob *other_job, *next;
+
+ if (txn->aborting) {
+ /*
+ * We are cancelled by another job, who will handle everything.
s/who/which/
+ */
+ return;
+ }
+ txn->aborting = true;
+ /* We are the first failed job. Cancel other jobs. */
+ QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
+ ctx = bdrv_get_aio_context(other_job->bs);
+ aio_context_acquire(ctx);
+ }
+ QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
+ if (other_job == job || other_job->completed) {
+ /* Other are "effectively" cancelled by us, so set the status for
s/Other/Other jobs/?
+ * them; this job, however, may or may not be cancelled, depending
+ * on the caller, so leave it. */
+ other_job->cancelled = other_job != job;
If other_job == job, this is not left as it was, but set to false.
+ continue;
+ }
+ block_job_cancel_sync(other_job);
+ assert(other_job->completed);
+ }
+ QLIST_FOREACH_SAFE(other_job, &txn->jobs, txn_list, next) {
+ ctx = bdrv_get_aio_context(other_job->bs);
+ block_job_completed_single(other_job);
+ aio_context_release(ctx);
+ }
+ g_free(txn);
+}
+
+static void block_job_completed_txn_success(BlockJob *job)
+{
+ AioContext *ctx;
+ BlockJobTxn *txn = job->txn;
+ BlockJob *other_job, *next;
+ /*
+ * Successful completion, see if there are other running jobs in this
+ * txn.
+ **/
+ QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
+ if (!other_job->completed) {
+ return;
+ }
+ }
+ /* We are the last completed job, commit the transaction. */
+ QLIST_FOREACH_SAFE(other_job, &txn->jobs, txn_list, next) {
+ ctx = bdrv_get_aio_context(other_job->bs);
+ aio_context_acquire(ctx);
+ assert(other_job->ret == 0);
+ block_job_completed_single(other_job);
+ aio_context_release(ctx);
+ }
+ g_free(txn);
+}
+
void block_job_completed(BlockJob *job, int ret)
{
BlockDriverState *bs = job->bs;
@@ -98,8 +185,13 @@ void block_job_completed(BlockJob *job, int ret)
assert(!job->completed);
job->completed = true;
job->ret = ret;
- job->cb(job->opaque, ret);
- block_job_unref(job);
+ if (!job->txn) {
+ block_job_completed_single(job);
+ } else if (ret < 0 || block_job_is_cancelled(job)) {
+ block_job_completed_txn_abort(job);
+ } else {
+ block_job_completed_txn_success(job);
+ }
}
void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp)
@@ -398,3 +490,22 @@ void block_job_defer_to_main_loop(BlockJob *job,
qemu_bh_schedule(data->bh);
}
+
+BlockJobTxn *block_job_txn_new(void)
+{
+ BlockJobTxn *txn = g_new0(BlockJobTxn, 1);
+ QLIST_INIT(&txn->jobs);
+ return txn;
+}
+
+void block_job_txn_add_job(BlockJobTxn *txn, BlockJob *job)
+{
+ if (!txn) {
+ return;
+ }
+
+ assert(!job->txn);
+ job->txn = txn;
+
+ QLIST_INSERT_HEAD(&txn->jobs, job, txn_list);
+}
diff --git a/include/block/block.h b/include/block/block.h
index b1116e9..b7e06a5 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -14,6 +14,7 @@ typedef struct BlockDriver BlockDriver;
typedef struct BlockJob BlockJob;
typedef struct BdrvChild BdrvChild;
typedef struct BdrvChildRole BdrvChildRole;
+typedef struct BlockJobTxn BlockJobTxn;
typedef struct BlockDriverInfo {
/* in bytes, 0 if irrelevant */
diff --git a/include/block/blockjob.h b/include/block/blockjob.h
index f6e4c86..c6b1bbb 100644
--- a/include/block/blockjob.h
+++ b/include/block/blockjob.h
@@ -152,6 +152,9 @@ struct BlockJob {
*/
int ret;
+ /** Non-NULL if this job is part of a transaction */
+ BlockJobTxn *txn;
+ QLIST_ENTRY(BlockJob) txn_list;
};
/**
@@ -395,4 +398,30 @@ void block_job_defer_to_main_loop(BlockJob *job,
BlockJobDeferToMainLoopFn *fn,
void *opaque);
+/**
+ * block_job_txn_new:
+ *
+ * Allocate and return a new block job transaction. Jobs can be added to the
+ * transaction using block_job_txn_add_job().
+ *
+ * The transaction is automatically freed when the last job completes or is
+ * cancelled.
+ *
+ * All jobs in the transaction either complete successfully or fail/cancel as a
+ * group. Jobs wait for each other before completing. Cancelling one job
+ * cancels all jobs in the transaction.
+ */
+BlockJobTxn *block_job_txn_new(void);
+
+/**
+ * block_job_txn_add_job:
+ * @txn: The transaction (may be NULL)
+ * @job: Job to add to the transaction
+ *
+ * Add @job to the transaction. The @job must not already be in a transaction.
+ * The block job driver must call block_job_txn_prepare_to_complete() before
+ * final cleanup and completion.
I see this function mentioned only here, only in this patch. That
doesn't seem right to me.
Max
+ */
+void block_job_txn_add_job(BlockJobTxn *txn, BlockJob *job);
+
#endif
