dm vdo: add the vdo io_submitter

The io_submitter handles bio submission from vdo data store to the storage
below. It will merge bios when possible.
Co-developed-by: J. corwin Coburn <corwin@hurlbutnet.net>
Signed-off-by: J. corwin Coburn <corwin@hurlbutnet.net>
Co-developed-by: Michael Sclafani <dm-devel@lists.linux.dev>
Signed-off-by: Michael Sclafani <dm-devel@lists.linux.dev>
Co-developed-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Co-developed-by: Bruce Johnston <bjohnsto@redhat.com>
Signed-off-by: Bruce Johnston <bjohnsto@redhat.com>
Co-developed-by: Ken Raeburn <raeburn@redhat.com>
Signed-off-by: Ken Raeburn <raeburn@redhat.com>
Signed-off-by: Matthew Sakai <msakai@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

drivers/md/dm-vdo/io-submitter.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#ifndef VDO_IO_SUBMITTER_H
+#define VDO_IO_SUBMITTER_H
+
+#include <linux/bio.h>
+
+#include "types.h"
+
+struct io_submitter;
+
+int vdo_make_io_submitter(unsigned int thread_count, unsigned int rotation_interval,
+			  unsigned int max_requests_active, struct vdo *vdo,
+			  struct io_submitter **io_submitter);
+
+void vdo_cleanup_io_submitter(struct io_submitter *io_submitter);
+
+void vdo_free_io_submitter(struct io_submitter *io_submitter);
+
+void process_vio_io(struct vdo_completion *completion);
+
+void submit_data_vio_io(struct data_vio *data_vio);
+
+void vdo_submit_metadata_io(struct vio *vio, physical_block_number_t physical,
+			    bio_end_io_t callback, vdo_action_fn error_handler,
+			    unsigned int operation, char *data);
+
+static inline void submit_metadata_vio(struct vio *vio, physical_block_number_t physical,
+				       bio_end_io_t callback, vdo_action_fn error_handler,
+				       unsigned int operation)
+{
+	vdo_submit_metadata_io(vio, physical, callback, error_handler,
+			       operation, vio->data);
+}
+
+static inline void submit_flush_vio(struct vio *vio, bio_end_io_t callback,
+				    vdo_action_fn error_handler)
+{
+	/* FIXME: Can we just use REQ_OP_FLUSH? */
+	vdo_submit_metadata_io(vio, 0, callback, error_handler,
+			       REQ_OP_WRITE | REQ_PREFLUSH, NULL);
+}
+
+#endif /* VDO_IO_SUBMITTER_H */