Changes from v2, which covers virtio-scsi as well:
- Patch 1: Review all bdrv_op_block_all callers.
Document bdrv_op_blocker_add_notifier.
Fix blocking in bdrv_op_blocker_notify.
- Patch 11: Commit message and function comment update.
- Patch 12: New.
Reported by Paolo.
Unlike the iohandler in main loop, iothreads currently process the event
notifier used by virtio-blk ioeventfd in nested aio_poll. This is dangerous
without proper protection, because guest requests could sneak to block layer
where they mustn't.
For example, a QMP transaction may involve multiple bdrv_drain_all() in
handling the list of AioContext it works on. If an aio_poll in one of the
bdrv_drain_all() happens to process a guest VQ kick, and dispatches the
ioeventfd event to virtio-blk, a new guest write is then submitted, and voila,
the transaction semantics is violated.
This series avoids this problem by disabling virtio-blk handlers during
bdrv_drain_all() and transactions.
- Patches 1~3 add the block layer op blocker change notifier code.
- Patches 4,5 secure virtio-blk dataplane.
- Patch 6 secures nbd export.
- Patch 7~10 protect each transaction type from being voilated by new IO
generated in nested aio_poll.
- Patch 11 protects bdrv_drain and bdrv_drain_all.
- Patch 12 does the same protection to virtio-scsi dataplane.
Fam Zheng (12):
block: Add op blocker type "device IO"
block: Add op blocker notifier list
block-backend: Add blk_op_blocker_add_notifier
virtio-blk: Move complete_request to 'ops' structure
virtio-blk: Don't handle output when there is "device IO" op blocker
nbd-server: Clear "can_read" when "device io" blocker is set
blockdev: Block device IO during internal snapshot transaction
blockdev: Block device IO during external snapshot transaction
blockdev: Block device IO during drive-backup transaction
blockdev: Block device IO during blockdev-backup transaction
block: Block "device IO" during bdrv_drain and bdrv_drain_all
virtio-scsi-dataplane: Add "device IO" op blocker listener
block.c | 35 ++++++++++++++++
block/block-backend.c | 6 +++
block/io.c | 22 +++++++++-
blockdev.c | 49 ++++++++++++++++++----
blockjob.c | 1 +
hw/block/dataplane/virtio-blk.c | 37 ++++++++++++++---
hw/block/virtio-blk.c | 69 +++++++++++++++++++++++++++++--
hw/scsi/virtio-scsi-dataplane.c | 91 ++++++++++++++++++++++++++++++++---------
hw/scsi/virtio-scsi.c | 4 ++
include/block/block.h | 9 ++++
include/block/block_int.h | 3 ++
include/hw/virtio/virtio-blk.h | 17 ++++++--
include/hw/virtio/virtio-scsi.h | 3 ++
include/sysemu/block-backend.h | 2 +
migration/block.c | 1 +
nbd.c | 18 ++++++++
16 files changed, 327 insertions(+), 40 deletions(-)
--
2.4.0
