v2:
* Protect block_job_defer_to_main_loop_bh() against AioContext change [Max]
* Drop unnecessary if (buf) around qemu_vfree(buf) [Max]
Almost all the infrastructure is in place to make blockjobs safe for use with
dataplane:
* Op blockers all us to exclude commands that could conflict with a blockjob
or dataplane.
* AioContext acquire/release allows threads to temporarily access a
BlockDriverState that is running in another thread.
This series introduces a few additional helpers:
* block_job_defer_to_main_loop() which allows blockjobs to run their
completion code in the QEMU main loop. This is necessary because some
operations are not safe outside the QEMU global mutex.
* bdrv_drain() which can be used in limited cases to wait for in-flight
requests to complete (as opposed to the global bdrv_drain_all() function).
The approach taken in this series is to convert the blockdev.c monitor command
so it acquires the BlockDriverState's AioContext. Normally only 1 AioContext
is involved at a time but the mirror job's to_replace argument can involve a
second AioContext.
Then the block job code itself is converted to defer main loop code using
block_job_defer_to_main_loop().
Example:
$ qemu-system-x86_64 -enable-kvm -m 1024 \
-drive if=none,id=drive0,file=test.img \
-object iothread,iothread0 \
-device virtio-blk-pci,drive=drive0,iothread=iothread0
(qemu) drive_mirror drive0 test2.img
Stefan Hajnoczi (11):
block: acquire AioContext in generic blockjob QMP commands
blockdev: acquire AioContext in do_qmp_query_block_jobs_one()
blockdev: acquire AioContext in blockdev_mark_auto_del()
blockdev: add note that block_job_cb() must be thread-safe
blockjob: add block_job_defer_to_main_loop()
block: add bdrv_drain()
block: let backup blockjob run in BDS AioContext
block: let stream blockjob run in BDS AioContext
block: let mirror blockjob run in BDS AioContext
block: let commit blockjob run in BDS AioContext
block: declare blockjobs and dataplane friends!
block.c | 49 +++++++++--
block/backup.c | 21 ++++-
block/commit.c | 70 ++++++++++------
block/mirror.c | 85 +++++++++++++------
block/stream.c | 50 +++++++----
blockdev.c | 179 +++++++++++++++++++++++++++++-----------
blockjob.c | 46 +++++++++++
hw/block/dataplane/virtio-blk.c | 5 ++
include/block/block.h | 1 +
include/block/blockjob.h | 19 +++++
10 files changed, 402 insertions(+), 123 deletions(-)
--
1.9.3
