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blockjobs: add prepare callback

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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>
This commit is contained in:
John Snow 2018-03-10 03:27:40 -05:00 • committed by Kevin Wolf
parent efe4d4b7b2
commit 2da4617a54
2 changed files with 37 additions and 3 deletions
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10
include/block/blockjob_int.h
View file

@ -53,6 +53,16 @@ struct BlockJobDriver {
*/
void (*complete)(BlockJob *job, Error **errp);
/**
* If the callback is not NULL, prepare will be invoked when all the jobs
* belonging to the same transaction complete; or upon this job's completion
* if it is not in a transaction.
*
* This callback will not be invoked if the job has already failed.
* If it fails, abort and then clean will be called.
*/
int (*prepare)(BlockJob *job);
/**
* If the callback is not NULL, it will be invoked when all the jobs
* belonging to the same transaction complete; or upon this job's