blockjobs: add prepare callback
Some jobs upon finalization may need to perform some work that can still fail. If these jobs are part of a transaction, it's important that these callbacks fail the entire transaction. We allow for a new callback in addition to commit/abort/clean that allows us the opportunity to have fairly late-breaking failures in the transactional process. The expected flow is: - All jobs in a transaction converge to the PENDING state, added in a forthcoming commit. - Upon being finalized, either automatically or explicitly by the user, jobs prepare to complete. - If any job fails preparation, all jobs call .abort. - Otherwise, they succeed and call .commit. Signed-off-by: John Snow <jsnow@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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efe4d4b7b2
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30
blockjob.c
30
blockjob.c
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@ -415,6 +415,14 @@ static void block_job_update_rc(BlockJob *job)
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}
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}
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}
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}
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static int block_job_prepare(BlockJob *job)
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{
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if (job->ret == 0 && job->driver->prepare) {
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job->ret = job->driver->prepare(job);
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}
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return job->ret;
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}
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static void block_job_commit(BlockJob *job)
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static void block_job_commit(BlockJob *job)
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{
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{
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assert(!job->ret);
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assert(!job->ret);
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@ -438,7 +446,7 @@ static void block_job_clean(BlockJob *job)
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}
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}
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}
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}
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static void block_job_completed_single(BlockJob *job)
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static int block_job_completed_single(BlockJob *job)
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{
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{
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assert(job->completed);
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assert(job->completed);
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@ -472,6 +480,7 @@ static void block_job_completed_single(BlockJob *job)
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QLIST_REMOVE(job, txn_list);
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QLIST_REMOVE(job, txn_list);
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block_job_txn_unref(job->txn);
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block_job_txn_unref(job->txn);
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block_job_conclude(job);
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block_job_conclude(job);
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return 0;
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}
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}
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static void block_job_cancel_async(BlockJob *job)
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static void block_job_cancel_async(BlockJob *job)
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@ -487,17 +496,22 @@ static void block_job_cancel_async(BlockJob *job)
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job->cancelled = true;
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job->cancelled = true;
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}
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}
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static void block_job_txn_apply(BlockJobTxn *txn, void fn(BlockJob *))
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static int block_job_txn_apply(BlockJobTxn *txn, int fn(BlockJob *))
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{
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{
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AioContext *ctx;
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AioContext *ctx;
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BlockJob *job, *next;
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BlockJob *job, *next;
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int rc = 0;
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QLIST_FOREACH_SAFE(job, &txn->jobs, txn_list, next) {
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QLIST_FOREACH_SAFE(job, &txn->jobs, txn_list, next) {
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ctx = blk_get_aio_context(job->blk);
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ctx = blk_get_aio_context(job->blk);
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aio_context_acquire(ctx);
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aio_context_acquire(ctx);
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fn(job);
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rc = fn(job);
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aio_context_release(ctx);
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aio_context_release(ctx);
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if (rc) {
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break;
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}
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}
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}
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return rc;
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}
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}
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static int block_job_finish_sync(BlockJob *job,
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static int block_job_finish_sync(BlockJob *job,
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@ -580,6 +594,8 @@ static void block_job_completed_txn_success(BlockJob *job)
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{
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{
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BlockJobTxn *txn = job->txn;
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BlockJobTxn *txn = job->txn;
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BlockJob *other_job;
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BlockJob *other_job;
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int rc = 0;
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/*
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/*
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* Successful completion, see if there are other running jobs in this
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* Successful completion, see if there are other running jobs in this
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* txn.
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* txn.
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@ -590,6 +606,14 @@ static void block_job_completed_txn_success(BlockJob *job)
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}
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}
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assert(other_job->ret == 0);
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assert(other_job->ret == 0);
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}
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}
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/* Jobs may require some prep-work to complete without failure */
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rc = block_job_txn_apply(txn, block_job_prepare);
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if (rc) {
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block_job_completed_txn_abort(job);
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return;
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}
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/* We are the last completed job, commit the transaction. */
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/* We are the last completed job, commit the transaction. */
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block_job_txn_apply(txn, block_job_completed_single);
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block_job_txn_apply(txn, block_job_completed_single);
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}
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}
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@ -53,6 +53,16 @@ struct BlockJobDriver {
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*/
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*/
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void (*complete)(BlockJob *job, Error **errp);
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void (*complete)(BlockJob *job, Error **errp);
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/**
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* If the callback is not NULL, prepare will be invoked when all the jobs
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* belonging to the same transaction complete; or upon this job's completion
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* if it is not in a transaction.
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*
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* This callback will not be invoked if the job has already failed.
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* If it fails, abort and then clean will be called.
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*/
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int (*prepare)(BlockJob *job);
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/**
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/**
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* If the callback is not NULL, it will be invoked when all the jobs
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* If the callback is not NULL, it will be invoked when all the jobs
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* belonging to the same transaction complete; or upon this job's
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* belonging to the same transaction complete; or upon this job's
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