[PATCH 4/6] io_uring/cancel: add generic cancel helper

[Jens Axboe <axboe@kernel.dk>]

Any opcode that is cancelable ends up defining its own cancel helper
for finding and canceling a specific request. Add a generic helper that
can be used for this purpose.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 io_uring/cancel.c | 21 +++++++++++++++++++++
 io_uring/cancel.h |  4 ++++
 2 files changed, 25 insertions(+)

diff --git a/io_uring/cancel.c b/io_uring/cancel.c
index 0565dc0d7611..4ff3771131c2 100644
--- a/io_uring/cancel.c
+++ b/io_uring/cancel.c
@@ -361,3 +361,24 @@ bool io_cancel_remove_all(struct io_ring_ctx *ctx, struct io_uring_task *tctx,
 
 	return found;
 }
+
+int io_cancel_remove(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
+		     unsigned int issue_flags, struct hlist_head *list,
+		     bool (*cancel)(struct io_kiocb *))
+{
+	struct hlist_node *tmp;
+	struct io_kiocb *req;
+	int nr = 0;
+
+	io_ring_submit_lock(ctx, issue_flags);
+	hlist_for_each_entry_safe(req, tmp, list, hash_node) {
+		if (!io_cancel_req_match(req, cd))
+			continue;
+		if (cancel(req))
+			nr++;
+		if (!(cd->flags & IORING_ASYNC_CANCEL_ALL))
+			break;
+	}
+	io_ring_submit_unlock(ctx, issue_flags);
+	return nr ?: -ENOENT;
+}
diff --git a/io_uring/cancel.h b/io_uring/cancel.h
index 80734a0a2b26..43e9bb74e9d1 100644
--- a/io_uring/cancel.h
+++ b/io_uring/cancel.h
@@ -28,6 +28,10 @@ bool io_cancel_remove_all(struct io_ring_ctx *ctx, struct io_uring_task *tctx,
 			  struct hlist_head *list, bool cancel_all,
 			  bool (*cancel)(struct io_kiocb *));
 
+int io_cancel_remove(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
+		     unsigned int issue_flags, struct hlist_head *list,
+		     bool (*cancel)(struct io_kiocb *));
+
 static inline bool io_cancel_match_sequence(struct io_kiocb *req, int sequence)
 {
 	if (req->cancel_seq_set && sequence == req->work.cancel_seq)
-- 
2.47.2