Background for this series is the following bug report, which is about a crash with virtio-blk + iothread and request resubmission for werror/rerror:
https://bugzilla.redhat.com/show_bug.cgi?id=1671173 The reason is that bdrv_set_aio_context() didn't correctly quiesce everything. Instead, it had a local hack to call aio_poll() for the source AioContext, which covered some, but not all cases, and is wrong because you can only call aio_poll() from the home thread. So this series tries to make bdrv_drain() actually drain the known cases (fixes virtio-blk and the NBD client) and use the regular drain functions in bdrv_set_aio_context() instead of open-coding something similar. v2: - New patch 5: Remove now redundant assignments [Paolo] - Patch 8 (was 7): Instead of using aio_co_schedule() to switch the AioContext and modifying the coroutine code, enter the coroutine in a BH in the new AioContext and bdrv_dec_in_flight() in that BH [Paolo] - Patch 12 (was 11): Cover new == old case in comment [Eric] Kevin Wolf (13): block-backend: Make blk_inc/dec_in_flight public virtio-blk: Increase in_flight for request restart BH nbd: Restrict connection_co reentrance io: Make qio_channel_yield() interruptible io: Remove redundant read/write_coroutine assignments nbd: Move nbd_read_eof() to nbd/client.c nbd: Use low-level QIOChannel API in nbd_read_eof() nbd: Increase bs->in_flight during AioContext switch block: Don't poll in bdrv_set_aio_context() block: Fix AioContext switch for drained node test-bdrv-drain: AioContext switch in drained section block: Use normal drain for bdrv_set_aio_context() aio-posix: Assert that aio_poll() is always called in home thread block/nbd-client.h | 1 + include/block/nbd.h | 3 +- include/io/channel.h | 9 ++++-- include/sysemu/block-backend.h | 2 ++ nbd/nbd-internal.h | 19 ------------- block.c | 26 ++++++++--------- block/block-backend.c | 4 +-- block/nbd-client.c | 36 +++++++++++++++++++++-- hw/block/virtio-blk.c | 4 +++ io/channel.c | 24 ++++++++++------ nbd/client.c | 52 ++++++++++++++++++++++++++++++++-- tests/test-bdrv-drain.c | 32 +++++++++++++++++++++ util/aio-posix.c | 3 +- 13 files changed, 164 insertions(+), 51 deletions(-) -- 2.20.1
