Ping! To clarify, I *do* intend this series to be for-2.5, and I think it does qualify as such.
If this *doesn't* go in, we have to revise our documentation just a pinch to undo some of Kashyap's changes that have already been merged in. Patches 5, 10, 11 and 12 are awaiting review. --js On 10/23/2015 07:56 PM, John Snow wrote: > Welcome to V10! > > Where'd 8 and 9 go? Private off-list missives from Fam. > Now you, I, and everyone on qemu-devel are staring at V10. > > What's new in V10? > > I replaced the per-action "transactional-cancel" parameter with > a per-transaction paremeter named "err-cancel" which is implemented > as an enum in case we want to add new behaviors in the future, such > as a "jobs only" cancel mode. > > For now, it's "all" or "none", and if you use it with actions that > do not support the latent transactional cancel, you will receive > an error for your troubles. > > This version primarily changed patches 10,11 and replaced it with > patches 10-12 that are cut a little differently. > > This is based on top of the work by Stefan Hajnoczi and Fam Zheng. > > Recap: motivation for block job transactions > -------------------------------------------- > If an incremental backup block job fails then we reclaim the bitmap so > the job can be retried. The problem comes when multiple jobs are started as > part of a qmp 'transaction' command. We need to group these jobs in a > transaction so that either all jobs complete successfully or all bitmaps are > reclaimed. > > Without transactions, there is a case where some jobs complete successfully > and > throw away their bitmaps, making it impossible to retry the backup by > rerunning > the command if one of the jobs fails. > > How does this implementation work? > ---------------------------------- > These patches add a BlockJobTxn object with the following API: > > txn = block_job_txn_new(); > block_job_txn_add_job(txn, job1); > block_job_txn_add_job(txn, job2); > > The jobs either both complete successfully or they both fail/cancel. If the > user cancels job1 then job2 will also be cancelled and vice versa. > > Jobs objects stay alive waiting for other jobs to complete, even if the > coroutines have returned. They can be cancelled by the user during this time. > Job blockers are still in effect and no other block job can run on this device > in the meantime (since QEMU currently only allows 1 job per device). This is > the main drawback to this approach but reasonable since you probably don't > want > to run other jobs/operations until you're sure the backup was successful (you > won't be able to retry a failed backup if there's a new job running). > > [History] > > v10: Replaced per-action parameter with per-transaction properties. > Patches 10,11 were split into 10-12. > > v9: this version fixes a reference count problem with job->bs, > in patch 05. > > v8: Rebase on to master. > Minor fixes addressing John Snow's comments. > > v7: Add Eric's rev-by in 1, 11. > Add Max's rev-by in 4, 5, 9, 10, 11. > Add John's rev-by in 5, 6, 8. > Fix wording for 6. [John] > Fix comment of block_job_txn_add_job() in 9. [Max] > Remove superfluous hunks, and document default value in 11. [Eric] > Update Makefile dep in 14. [Max] > > ________________________________________________________________________________ > > For convenience, this branch is available at: > https://github.com/jnsnow/qemu.git branch block-transpop > https://github.com/jnsnow/qemu/tree/block-transpop > > This version is tagged block-transpop-v10: > https://github.com/jnsnow/qemu/releases/tag/block-transpop-v10 > > Fam Zheng (6): > backup: Extract dirty bitmap handling as a separate function > blockjob: Introduce reference count and fix reference to job->bs > blockjob: Add .commit and .abort block job actions > blockjob: Add "completed" and "ret" in BlockJob > blockjob: Simplify block_job_finish_sync > block: Add block job transactions > > John Snow (7): > qapi: Add transaction support to block-dirty-bitmap operations > iotests: add transactional incremental backup test > block: rename BlkTransactionState and BdrvActionOps > block/backup: Rely on commit/abort for cleanup > block: Add BlockJobTxn support to backup_run > block: add transactional properties > iotests: 124 - transactional failure test > > Stefan Hajnoczi (1): > tests: add BlockJobTxn unit test > > block.c | 19 +- > block/backup.c | 50 ++++-- > block/mirror.c | 2 +- > blockdev.c | 430 > ++++++++++++++++++++++++++++++++++----------- > blockjob.c | 188 ++++++++++++++++---- > docs/bitmaps.md | 6 +- > include/block/block.h | 2 +- > include/block/block_int.h | 6 +- > include/block/blockjob.h | 85 ++++++++- > qapi-schema.json | 54 +++++- > qemu-img.c | 3 - > qmp-commands.hx | 2 +- > tests/Makefile | 3 + > tests/qemu-iotests/124 | 182 ++++++++++++++++++- > tests/qemu-iotests/124.out | 4 +- > tests/test-blockjob-txn.c | 244 +++++++++++++++++++++++++ > 16 files changed, 1108 insertions(+), 172 deletions(-) > create mode 100644 tests/test-blockjob-txn.c >
