io_uring/cancel: add generic remove_all helper

Any opcode that is cancelable ends up defining its own remove all
helper, which iterates the pending list and cancels matches. Add a
generic helper for it, which can be used by them.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/cancel.c

@@ -341,3 +341,24 @@ int io_sync_cancel(struct io_ring_ctx *ctx, void __user *arg)
 		fput(file);
 	return ret;
 }
+
+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 *))
+{
+	struct hlist_node *tmp;
+	struct io_kiocb *req;
+	bool found = false;
+
+	lockdep_assert_held(&ctx->uring_lock);
+
+	hlist_for_each_entry_safe(req, tmp, list, hash_node) {
+		if (!io_match_task_safe(req, tctx, cancel_all))
+			continue;
+		hlist_del_init(&req->hash_node);
+		if (cancel(req))
+			found = true;
+	}
+
+	return found;
+}

io_uring/cancel.h

@@ -24,6 +24,10 @@ int io_try_cancel(struct io_uring_task *tctx, struct io_cancel_data *cd,
 int io_sync_cancel(struct io_ring_ctx *ctx, void __user *arg);
 bool io_cancel_req_match(struct io_kiocb *req, struct io_cancel_data *cd);
 
+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 *));
+
 static inline bool io_cancel_match_sequence(struct io_kiocb *req, int sequence)
 {
 	if (req->cancel_seq_set && sequence == req->work.cancel_seq)