dm vdo: add vio, the request object for vdo metadata

Add the data and methods that implement the vio object that is basic
unit of I/O in vdo.
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/vio.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#ifndef VIO_H
+#define VIO_H
+
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+
+#include "completion.h"
+#include "constants.h"
+#include "types.h"
+#include "vdo.h"
+
+enum {
+	MAX_BLOCKS_PER_VIO = (BIO_MAX_VECS << PAGE_SHIFT) / VDO_BLOCK_SIZE,
+};
+
+struct pooled_vio {
+	/* The underlying vio */
+	struct vio vio;
+	/* The list entry for chaining pooled vios together */
+	struct list_head list_entry;
+	/* The context set by the pool */
+	void *context;
+	/* The list entry used by the pool */
+	struct list_head pool_entry;
+};
+
+/**
+ * as_vio() - Convert a generic vdo_completion to a vio.
+ * @completion: The completion to convert.
+ *
+ * Return: The completion as a vio.
+ */
+static inline struct vio *as_vio(struct vdo_completion *completion)
+{
+	vdo_assert_completion_type(completion, VIO_COMPLETION);
+	return container_of(completion, struct vio, completion);
+}
+
+/**
+ * get_vio_bio_zone_thread_id() - Get the thread id of the bio zone in which a vio should submit
+ *                                its I/O.
+ * @vio: The vio.
+ *
+ * Return: The id of the bio zone thread the vio should use.
+ */
+static inline thread_id_t __must_check get_vio_bio_zone_thread_id(struct vio *vio)
+{
+	return vio->completion.vdo->thread_config.bio_threads[vio->bio_zone];
+}
+
+physical_block_number_t __must_check pbn_from_vio_bio(struct bio *bio);
+
+/**
+ * assert_vio_in_bio_zone() - Check that a vio is running on the correct thread for its bio zone.
+ * @vio: The vio to check.
+ */
+static inline void assert_vio_in_bio_zone(struct vio *vio)
+{
+	thread_id_t expected = get_vio_bio_zone_thread_id(vio);
+	thread_id_t thread_id = vdo_get_callback_thread_id();
+
+	ASSERT_LOG_ONLY((expected == thread_id),
+			"vio I/O for physical block %llu on thread %u, should be on bio zone thread %u",
+			(unsigned long long) pbn_from_vio_bio(vio->bio), thread_id,
+			expected);
+}
+
+int vdo_create_bio(struct bio **bio_ptr);
+void vdo_free_bio(struct bio *bio);
+int allocate_vio_components(struct vdo *vdo, enum vio_type vio_type,
+			    enum vio_priority priority, void *parent,
+			    unsigned int block_count, char *data, struct vio *vio);
+int __must_check create_multi_block_metadata_vio(struct vdo *vdo, enum vio_type vio_type,
+						 enum vio_priority priority,
+						 void *parent, unsigned int block_count,
+						 char *data, struct vio **vio_ptr);
+
+static inline int __must_check create_metadata_vio(struct vdo *vdo, enum vio_type vio_type,
+						   enum vio_priority priority,
+						   void *parent, char *data,
+						   struct vio **vio_ptr)
+{
+	return create_multi_block_metadata_vio(vdo, vio_type, priority, parent, 1, data,
+					       vio_ptr);
+}
+
+void free_vio_components(struct vio *vio);
+void free_vio(struct vio *vio);
+
+/**
+ * initialize_vio() - Initialize a vio.
+ * @vio: The vio to initialize.
+ * @bio: The bio this vio should use for its I/O.
+ * @block_count: The size of this vio in vdo blocks.
+ * @vio_type: The vio type.
+ * @priority: The relative priority of the vio.
+ * @vdo: The vdo for this vio.
+ */
+static inline void initialize_vio(struct vio *vio, struct bio *bio,
+				  unsigned int block_count, enum vio_type vio_type,
+				  enum vio_priority priority, struct vdo *vdo)
+{
+	/* data_vio's may not span multiple blocks */
+	BUG_ON((vio_type == VIO_TYPE_DATA) && (block_count != 1));
+
+	vio->bio = bio;
+	vio->block_count = block_count;
+	vio->type = vio_type;
+	vio->priority = priority;
+	vdo_initialize_completion(&vio->completion, vdo, VIO_COMPLETION);
+}
+
+void vdo_set_bio_properties(struct bio *bio, struct vio *vio, bio_end_io_t callback,
+			    unsigned int bi_opf, physical_block_number_t pbn);
+
+int vio_reset_bio(struct vio *vio, char *data, bio_end_io_t callback,
+		  unsigned int bi_opf, physical_block_number_t pbn);
+
+void update_vio_error_stats(struct vio *vio, const char *format, ...)
+	__printf(2, 3);
+
+/**
+ * is_data_vio() - Check whether a vio is servicing an external data request.
+ * @vio: The vio to check.
+ */
+static inline bool is_data_vio(struct vio *vio)
+{
+	return (vio->type == VIO_TYPE_DATA);
+}
+
+/**
+ * get_metadata_priority() - Convert a vio's priority to a work item priority.
+ * @vio: The vio.
+ *
+ * Return: The priority with which to submit the vio's bio.
+ */
+static inline enum vdo_completion_priority get_metadata_priority(struct vio *vio)
+{
+	return ((vio->priority == VIO_PRIORITY_HIGH) ?
+		BIO_Q_HIGH_PRIORITY :
+		BIO_Q_METADATA_PRIORITY);
+}
+
+/**
+ * continue_vio() - Enqueue a vio to run its next callback.
+ * @vio: The vio to continue.
+ *
+ * Return: The result of the current operation.
+ */
+static inline void continue_vio(struct vio *vio, int result)
+{
+	if (unlikely(result != VDO_SUCCESS))
+		vdo_set_completion_result(&vio->completion, result);
+
+	vdo_enqueue_completion(&vio->completion, VDO_WORK_Q_DEFAULT_PRIORITY);
+}
+
+void vdo_count_bios(struct atomic_bio_stats *bio_stats, struct bio *bio);
+void vdo_count_completed_bios(struct bio *bio);
+
+/**
+ * continue_vio_after_io() - Continue a vio now that its I/O has returned.
+ */
+static inline void continue_vio_after_io(struct vio *vio, vdo_action_fn callback,
+					 thread_id_t thread)
+{
+	vdo_count_completed_bios(vio->bio);
+	vdo_set_completion_callback(&vio->completion, callback, thread);
+	continue_vio(vio, blk_status_to_errno(vio->bio->bi_status));
+}
+
+void vio_record_metadata_io_error(struct vio *vio);
+
+/* A vio_pool is a collection of preallocated vios used to write arbitrary metadata blocks. */
+
+static inline struct pooled_vio *vio_as_pooled_vio(struct vio *vio)
+{
+	return container_of(vio, struct pooled_vio, vio);
+}
+
+struct vio_pool;
+
+int __must_check make_vio_pool(struct vdo *vdo, size_t pool_size, thread_id_t thread_id,
+			       enum vio_type vio_type, enum vio_priority priority,
+			       void *context, struct vio_pool **pool_ptr);
+void free_vio_pool(struct vio_pool *pool);
+bool __must_check is_vio_pool_busy(struct vio_pool *pool);
+void acquire_vio_from_pool(struct vio_pool *pool, struct waiter *waiter);
+void return_vio_to_pool(struct vio_pool *pool, struct pooled_vio *vio);
+
+#endif /* VIO_H */