dm vdo: add the block map

The block map contains the logical to physical mapping. It can be thought
of as an array with one entry per logical address. Each entry is 5 bytes:
36 bits contain the physical block number which holds the data for the
given logical address, and the remaining 4 bits are used to indicate the
nature of the mapping. Of the 16 possible states, one represents a logical
address which is unmapped (i.e. it has never been written, or has been
discarded), one represents an uncompressed block, and the other 14 states
are used to indicate that the mapped data is compressed, and which of the
compression slots in the compressed block this logical address maps to.
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>
Signed-off-by: Matthew Sakai <msakai@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

drivers/md/dm-vdo/block-map.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#ifndef VDO_BLOCK_MAP_H
+#define VDO_BLOCK_MAP_H
+
+#include <linux/list.h>
+
+#include "numeric.h"
+
+#include "admin-state.h"
+#include "completion.h"
+#include "encodings.h"
+#include "int-map.h"
+#include "statistics.h"
+#include "types.h"
+#include "vio.h"
+#include "wait-queue.h"
+
+enum {
+	BLOCK_MAP_VIO_POOL_SIZE = 64,
+};
+
+/*
+ * Generation counter for page references.
+ */
+typedef u32 vdo_page_generation;
+
+extern const struct block_map_entry UNMAPPED_BLOCK_MAP_ENTRY;
+
+struct forest;
+
+struct tree_page {
+	struct waiter waiter;
+
+	/* Dirty list entry */
+	struct list_head entry;
+
+	/* If dirty, the tree zone flush generation in which it was last dirtied. */
+	u8 generation;
+
+	/* Whether this page is an interior tree page being written out. */
+	bool writing;
+
+	/* If writing, the tree zone flush generation of the copy being written. */
+	u8 writing_generation;
+
+	/*
+	 * Sequence number of the earliest recovery journal block containing uncommitted updates to
+	 * this page
+	 */
+	sequence_number_t recovery_lock;
+
+	/* The value of recovery_lock when the this page last started writing */
+	sequence_number_t writing_recovery_lock;
+
+	char page_buffer[VDO_BLOCK_SIZE];
+};
+
+enum block_map_page_type {
+	VDO_TREE_PAGE,
+	VDO_CACHE_PAGE,
+};
+
+typedef struct list_head dirty_era_t[2];
+
+struct dirty_lists {
+	/** The number of periods after which an element will be expired */
+	block_count_t maximum_age;
+	/** The oldest period which has unexpired elements */
+	sequence_number_t oldest_period;
+	/** One more than the current period */
+	sequence_number_t next_period;
+	/** The offset in the array of lists of the oldest period */
+	block_count_t offset;
+	/** Expired pages */
+	dirty_era_t expired;
+	/** The lists of dirty pages */
+	dirty_era_t eras[];
+};
+
+struct block_map_zone {
+	zone_count_t zone_number;
+	thread_id_t thread_id;
+	struct admin_state state;
+	struct block_map *block_map;
+	/* Dirty pages, by era*/
+	struct dirty_lists *dirty_lists;
+	struct vdo_page_cache page_cache;
+	data_vio_count_t active_lookups;
+	struct int_map *loading_pages;
+	struct vio_pool *vio_pool;
+	/* The tree page which has issued or will be issuing a flush */
+	struct tree_page *flusher;
+	struct wait_queue flush_waiters;
+	/* The generation after the most recent flush */
+	u8 generation;
+	u8 oldest_generation;
+	/* The counts of dirty pages in each generation */
+	u32 dirty_page_counts[256];
+};
+
+struct block_map {
+	struct vdo *vdo;
+	struct action_manager *action_manager;
+	/* The absolute PBN of the first root of the tree part of the block map */
+	physical_block_number_t root_origin;
+	block_count_t root_count;
+
+	/* The era point we are currently distributing to the zones */
+	sequence_number_t current_era_point;
+	/* The next era point */
+	sequence_number_t pending_era_point;
+
+	/* The number of entries in block map */
+	block_count_t entry_count;
+	nonce_t nonce;
+	struct recovery_journal *journal;
+
+	/* The trees for finding block map pages */
+	struct forest *forest;
+	/* The expanded trees awaiting growth */
+	struct forest *next_forest;
+	/* The number of entries after growth */
+	block_count_t next_entry_count;
+
+	zone_count_t zone_count;
+	struct block_map_zone zones[];
+};
+
+/**
+ * typedef vdo_entry_callback_fn - A function to be called for each allocated PBN when traversing
+ *                                 the forest.
+ * @pbn: A PBN of a tree node.
+ * @completion: The parent completion of the traversal.
+ *
+ * Return: VDO_SUCCESS or an error.
+ */
+typedef int (*vdo_entry_callback_fn)(physical_block_number_t pbn,
+				     struct vdo_completion *completion);
+
+static inline struct block_map_page * __must_check
+vdo_as_block_map_page(struct tree_page *tree_page)
+{
+	return (struct block_map_page *) tree_page->page_buffer;
+}
+
+bool vdo_copy_valid_page(char *buffer, nonce_t nonce,
+			 physical_block_number_t pbn,
+			 struct block_map_page *page);
+
+void vdo_find_block_map_slot(struct data_vio *data_vio);
+
+physical_block_number_t vdo_find_block_map_page_pbn(struct block_map *map,
+						    page_number_t page_number);
+
+void vdo_write_tree_page(struct tree_page *page, struct block_map_zone *zone);
+
+void vdo_traverse_forest(struct block_map *map, vdo_entry_callback_fn callback,
+			 struct vdo_completion *parent);
+
+int __must_check vdo_decode_block_map(struct block_map_state_2_0 state,
+				      block_count_t logical_blocks, struct vdo *vdo,
+				      struct recovery_journal *journal, nonce_t nonce,
+				      page_count_t cache_size, block_count_t maximum_age,
+				      struct block_map **map_ptr);
+
+void vdo_drain_block_map(struct block_map *map, const struct admin_state_code *operation,
+			 struct vdo_completion *parent);
+
+void vdo_resume_block_map(struct block_map *map, struct vdo_completion *parent);
+
+int __must_check vdo_prepare_to_grow_block_map(struct block_map *map,
+					       block_count_t new_logical_blocks);
+
+void vdo_grow_block_map(struct block_map *map, struct vdo_completion *parent);
+
+void vdo_abandon_block_map_growth(struct block_map *map);
+
+void vdo_free_block_map(struct block_map *map);
+
+struct block_map_state_2_0 __must_check vdo_record_block_map(const struct block_map *map);
+
+void vdo_initialize_block_map_from_journal(struct block_map *map,
+					   struct recovery_journal *journal);
+
+zone_count_t vdo_compute_logical_zone(struct data_vio *data_vio);
+
+void vdo_advance_block_map_era(struct block_map *map,
+			       sequence_number_t recovery_block_number);
+
+void vdo_update_block_map_page(struct block_map_page *page, struct data_vio *data_vio,
+			       physical_block_number_t pbn,
+			       enum block_mapping_state mapping_state,
+			       sequence_number_t *recovery_lock);
+
+void vdo_get_mapped_block(struct data_vio *data_vio);
+
+void vdo_put_mapped_block(struct data_vio *data_vio);
+
+struct block_map_statistics __must_check vdo_get_block_map_statistics(struct block_map *map);
+
+/**
+ * vdo_convert_maximum_age() - Convert the maximum age to reflect the new recovery journal format
+ * @age: The configured maximum age
+ *
+ * Return: The converted age
+ *
+ * In the old recovery journal format, each journal block held 311 entries, and every write bio
+ * made two entries. The old maximum age was half the usable journal length. In the new format,
+ * each block holds only 217 entries, but each bio only makes one entry. We convert the configured
+ * age so that the number of writes in a block map era is the same in the old and new formats. This
+ * keeps the bound on the amount of work required to recover the block map from the recovery
+ * journal the same across the format change. It also keeps the amortization of block map page
+ * writes to write bios the same.
+ */
+static inline block_count_t vdo_convert_maximum_age(block_count_t age)
+{
+	return DIV_ROUND_UP(age * RECOVERY_JOURNAL_1_ENTRIES_PER_BLOCK,
+			    2 * RECOVERY_JOURNAL_ENTRIES_PER_BLOCK);
+}
+
+#endif /* VDO_BLOCK_MAP_H */