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From:   Pavel Begunkov <asml.silence@gmail.com>
To:     Jens Axboe <axboe@kernel.dk>, io-uring@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH 1/4] io-wq: reorder cancellation pending -> running
Date:   Sun,  7 Jun 2020 18:32:22 +0300
Message-Id: <4d250faf3029d6bd31973276701d5971db696004.1591541128.git.asml.silence@gmail.com>
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References: <cover.1591541128.git.asml.silence@gmail.com>
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Precedence: bulk

Go all over all pending lists and cancel works there, and only then
try to match running requests. No functional changes here, just a
preparation for bulk cancellation.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io-wq.c | 54 ++++++++++++++++++++++++++++++++----------------------
 1 file changed, 32 insertions(+), 22 deletions(-)

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 4023c9846860..3283f8c5b5a1 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -931,19 +931,14 @@ static bool io_wq_worker_cancel(struct io_worker *worker, void *data)
 	return ret;
 }
 
-static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
-					    struct io_cb_cancel_data *match)
+static bool io_wqe_cancel_pending_work(struct io_wqe *wqe,
+				       struct io_cb_cancel_data *match)
 {
 	struct io_wq_work_node *node, *prev;
 	struct io_wq_work *work;
 	unsigned long flags;
 	bool found = false;
 
-	/*
-	 * First check pending list, if we're lucky we can just remove it
-	 * from there. CANCEL_OK means that the work is returned as-new,
-	 * no completion will be posted for it.
-	 */
 	spin_lock_irqsave(&wqe->lock, flags);
 	wq_list_for_each(node, prev, &wqe->work_list) {
 		work = container_of(node, struct io_wq_work, list);
@@ -956,21 +951,20 @@ static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
 	}
 	spin_unlock_irqrestore(&wqe->lock, flags);
 
-	if (found) {
+	if (found)
 		io_run_cancel(work, wqe);
-		return IO_WQ_CANCEL_OK;
-	}
+	return found;
+}
+
+static bool io_wqe_cancel_running_work(struct io_wqe *wqe,
+				       struct io_cb_cancel_data *match)
+{
+	bool found;
 
-	/*
-	 * Now check if a free (going busy) or busy worker has the work
-	 * currently running. If we find it there, we'll return CANCEL_RUNNING
-	 * as an indication that we attempt to signal cancellation. The
-	 * completion will run normally in this case.
-	 */
 	rcu_read_lock();
 	found = io_wq_for_each_worker(wqe, io_wq_worker_cancel, match);
 	rcu_read_unlock();
-	return found ? IO_WQ_CANCEL_RUNNING : IO_WQ_CANCEL_NOTFOUND;
+	return found;
 }
 
 enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
@@ -980,18 +974,34 @@ enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
 		.fn	= cancel,
 		.data	= data,
 	};
-	enum io_wq_cancel ret = IO_WQ_CANCEL_NOTFOUND;
 	int node;
 
+	/*
+	 * First check pending list, if we're lucky we can just remove it
+	 * from there. CANCEL_OK means that the work is returned as-new,
+	 * no completion will be posted for it.
+	 */
 	for_each_node(node) {
 		struct io_wqe *wqe = wq->wqes[node];
 
-		ret = io_wqe_cancel_work(wqe, &match);
-		if (ret != IO_WQ_CANCEL_NOTFOUND)
-			break;
+		if (io_wqe_cancel_pending_work(wqe, &match))
+			return IO_WQ_CANCEL_OK;
 	}
 
-	return ret;
+	/*
+	 * Now check if a free (going busy) or busy worker has the work
+	 * currently running. If we find it there, we'll return CANCEL_RUNNING
+	 * as an indication that we attempt to signal cancellation. The
+	 * completion will run normally in this case.
+	 */
+	for_each_node(node) {
+		struct io_wqe *wqe = wq->wqes[node];
+
+		if (io_wqe_cancel_running_work(wqe, &match))
+			return IO_WQ_CANCEL_RUNNING;
+	}
+
+	return IO_WQ_CANCEL_NOTFOUND;
 }
 
 static bool io_wq_io_cb_cancel_data(struct io_wq_work *work, void *data)
-- 
2.24.0