v6:
- Fix scsi_device_unrealize() -> scsi_qdev_unrealize() mistake in Patch 4
commit description [Kevin]
- Explain why we don't schedule a BH in .drained_begin() in Patch 16 [Kevin]
- Copy the comment explaining why the event notifier is tested and cleared in
Patch 16 [Kevin]
- Fix EPOLL_ENABLE_THRESHOLD mismerge in util/fdmon-epoll.c [Kevin]
v5:
- Use atomic accesses for in_flight counter in vhost-user-server.c [Kevin]
- Stash SCSIDevice id/lun values for VIRTIO_SCSI_T_TRANSPORT_RESET event
before unrealizing the SCSIDevice [Kevin]
- Keep vhost-user-blk export .detach() callback so ctx is set to NULL [Kevin]
- Narrow BdrvChildClass and BlockDriver drained_{begin/end/poll} callbacks from
IO_OR_GS_CODE() to GLOBAL_STATE_CODE() [Kevin]
- Include Kevin's "block: Fix use after free in blockdev_mark_auto_del()" to
fix a latent bug that was exposed by this series
v4:
- Remove external_disable_cnt variable [Philippe]
- Add Patch 1 to fix assertion failure in .drained_end() -> blk_get_aio_context()
v3:
- Resend full patch series. v2 was sent in the middle of a git rebase and was
missing patches. [Eric]
- Apply Reviewed-by tags.
v2:
- Do not rely on BlockBackend request queuing, implement .drained_begin/end()
instead in xen-block, virtio-blk, and virtio-scsi [Paolo]
- Add qdev_is_realized() API [Philippe]
- Add patch to avoid AioContext lock around blk_exp_ref/unref() [Paolo]
- Add patch to call .drained_begin/end() from main loop thread to simplify
callback implementations
The aio_disable_external() API temporarily suspends file descriptor monitoring
in the event loop. The block layer uses this to prevent new I/O requests being
submitted from the guest and elsewhere between bdrv_drained_begin() and
bdrv_drained_end().
While the block layer still needs to prevent new I/O requests in drained
sections, the aio_disable_external() API can be replaced with
.drained_begin/end/poll() callbacks that have been added to BdrvChildClass and
BlockDevOps.
This newer .bdrained_begin/end/poll() approach is attractive because it works
without specifying a specific AioContext. The block layer is moving towards
multi-queue and that means multiple AioContexts may be processing I/O
simultaneously.
The aio_disable_external() was always somewhat hacky. It suspends all file
descriptors that were registered with is_external=true, even if they have
nothing to do with the BlockDriverState graph nodes that are being drained.
It's better to solve a block layer problem in the block layer than to have an
odd event loop API solution.
The approach in this patch series is to implement BlockDevOps
.drained_begin/end() callbacks that temporarily stop file descriptor handlers.
This ensures that new I/O requests are not submitted in drained sections.
Stefan Hajnoczi (20):
block-backend: split blk_do_set_aio_context()
hw/qdev: introduce qdev_is_realized() helper
virtio-scsi: avoid race between unplug and transport event
virtio-scsi: stop using aio_disable_external() during unplug
util/vhost-user-server: rename refcount to in_flight counter
block/export: wait for vhost-user-blk requests when draining
block/export: stop using is_external in vhost-user-blk server
hw/xen: do not use aio_set_fd_handler(is_external=true) in
xen_xenstore
block: add blk_in_drain() API
block: drain from main loop thread in bdrv_co_yield_to_drain()
xen-block: implement BlockDevOps->drained_begin()
hw/xen: do not set is_external=true on evtchn fds
block/export: rewrite vduse-blk drain code
block/export: don't require AioContext lock around blk_exp_ref/unref()
block/fuse: do not set is_external=true on FUSE fd
virtio: make it possible to detach host notifier from any thread
virtio-blk: implement BlockDevOps->drained_begin()
virtio-scsi: implement BlockDevOps->drained_begin()
virtio: do not set is_external=true on host notifiers
aio: remove aio_disable_external() API
hw/block/dataplane/xen-block.h | 2 +
include/block/aio.h | 57 ---------
include/block/block_int-common.h | 90 +++++++-------
include/block/export.h | 2 +
include/hw/qdev-core.h | 17 ++-
include/hw/scsi/scsi.h | 14 +++
include/qemu/vhost-user-server.h | 8 +-
include/sysemu/block-backend-common.h | 25 ++--
include/sysemu/block-backend-global-state.h | 1 +
util/aio-posix.h | 1 -
block.c | 7 --
block/blkio.c | 15 +--
block/block-backend.c | 78 ++++++------
block/curl.c | 10 +-
block/export/export.c | 13 +-
block/export/fuse.c | 56 ++++++++-
block/export/vduse-blk.c | 128 ++++++++++++++------
block/export/vhost-user-blk-server.c | 52 +++++++-
block/io.c | 16 ++-
block/io_uring.c | 4 +-
block/iscsi.c | 3 +-
block/linux-aio.c | 4 +-
block/nfs.c | 5 +-
block/nvme.c | 8 +-
block/ssh.c | 4 +-
block/win32-aio.c | 6 +-
hw/block/dataplane/virtio-blk.c | 23 +++-
hw/block/dataplane/xen-block.c | 42 +++++--
hw/block/virtio-blk.c | 38 +++++-
hw/block/xen-block.c | 24 +++-
hw/i386/kvm/xen_xenstore.c | 2 +-
hw/scsi/scsi-bus.c | 46 ++++++-
hw/scsi/scsi-disk.c | 27 ++++-
hw/scsi/virtio-scsi-dataplane.c | 32 +++--
hw/scsi/virtio-scsi.c | 127 ++++++++++++++-----
hw/virtio/virtio.c | 9 +-
hw/xen/xen-bus.c | 11 +-
io/channel-command.c | 6 +-
io/channel-file.c | 3 +-
io/channel-socket.c | 3 +-
migration/rdma.c | 16 +--
tests/unit/test-aio.c | 27 +----
tests/unit/test-bdrv-drain.c | 15 +--
tests/unit/test-fdmon-epoll.c | 73 -----------
util/aio-posix.c | 20 +--
util/aio-win32.c | 8 +-
util/async.c | 3 +-
util/fdmon-epoll.c | 10 --
util/fdmon-io_uring.c | 8 +-
util/fdmon-poll.c | 3 +-
util/main-loop.c | 7 +-
util/qemu-coroutine-io.c | 7 +-
util/vhost-user-server.c | 33 ++---
hw/scsi/trace-events | 2 +
tests/unit/meson.build | 3 -
55 files changed, 725 insertions(+), 529 deletions(-)
delete mode 100644 tests/unit/test-fdmon-epoll.c
--
2.40.1