io_uring: replace workqueue usage with io-wq
Drop various work-arounds we have for workqueues:
- We no longer need the async_list for tracking sequential IO.
- We don't have to maintain our own mm tracking/setting.
- We don't need a separate workqueue for buffered writes. This didn't
even work that well to begin with, as it was suboptimal for multiple
buffered writers on multiple files.
- We can properly cancel pending interruptible work. This fixes
deadlocks with particularly socket IO, where we cannot cancel them
when the io_uring is closed. Hence the ring will wait forever for
these requests to complete, which may never happen. This is different
from disk IO where we know requests will complete in a finite amount
of time.
- Due to being able to cancel work interruptible work that is already
running, we can implement file table support for work. We need that
for supporting system calls that add to a process file table.
- It gets us one step closer to adding async support for any system
call.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/init/Kconfig b/init/Kconfig
index b4daad2..4d8d145 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1548,6 +1548,7 @@
config IO_URING
bool "Enable IO uring support" if EXPERT
select ANON_INODES
+ select IO_WQ
default y
help
This option enables support for the io_uring interface, enabling