io-wq: allow grabbing existing io-wq

Export a helper to attach to an existing io-wq, rather than setting up
a new one. This is doable now that we have reference counted io_wq's.

Reported-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 8 insertions, 0 deletions

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 7ccedc82a703..f7eb577ccd2d 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -1114,6 +1114,14 @@ err:
 	return ERR_PTR(ret);
 }
 
+bool io_wq_get(struct io_wq *wq, struct io_wq_data *data)
+{
+	if (data->get_work != wq->get_work || data->put_work != wq->put_work)
+		return false;
+
+	return refcount_inc_not_zero(&wq->use_refs);
+}
+
 static bool io_wq_worker_wake(struct io_worker *worker, void *data)
 {
 	wake_up_process(worker->task);