dm vdo: add hash locks and hash zones

In order to deduplicate concurrent writes of the same data (to different
locations), data_vios which are writing the same data are grouped together
in a "hash lock," named for and keyed by the hash of the data being
written. Each hash lock is assigned to a hash zone based on a portion of
its hash.
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/dedupe.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#ifndef VDO_DEDUPE_H
+#define VDO_DEDUPE_H
+
+#include <linux/list.h>
+#include <linux/timer.h>
+
+#include "uds.h"
+
+#include "admin-state.h"
+#include "constants.h"
+#include "statistics.h"
+#include "types.h"
+#include "wait-queue.h"
+
+struct dedupe_context {
+	struct hash_zone *zone;
+	struct uds_request request;
+	struct list_head list_entry;
+	struct funnel_queue_entry queue_entry;
+	u64 submission_jiffies;
+	struct data_vio *requestor;
+	atomic_t state;
+};
+
+struct hash_lock;
+
+struct hash_zone {
+	/* Which hash zone this is */
+	zone_count_t zone_number;
+
+	/* The administrative state of the zone */
+	struct admin_state state;
+
+	/* The thread ID for this zone */
+	thread_id_t thread_id;
+
+	/* Mapping from record name fields to hash_locks */
+	struct pointer_map *hash_lock_map;
+
+	/* List containing all unused hash_locks */
+	struct list_head lock_pool;
+
+	/*
+	 * Statistics shared by all hash locks in this zone. Only modified on the hash zone thread,
+	 * but queried by other threads.
+	 */
+	struct hash_lock_statistics statistics;
+
+	/* Array of all hash_locks */
+	struct hash_lock *lock_array;
+
+	/* These fields are used to manage the dedupe contexts */
+	struct list_head available;
+	struct list_head pending;
+	struct funnel_queue *timed_out_complete;
+	struct timer_list timer;
+	struct vdo_completion completion;
+	unsigned int active;
+	atomic_t timer_state;
+
+	/* The dedupe contexts for querying the index from this zone */
+	struct dedupe_context contexts[MAXIMUM_VDO_USER_VIOS];
+};
+
+struct hash_zones;
+
+struct pbn_lock * __must_check vdo_get_duplicate_lock(struct data_vio *data_vio);
+
+void vdo_acquire_hash_lock(struct vdo_completion *completion);
+void vdo_continue_hash_lock(struct vdo_completion *completion);
+void vdo_release_hash_lock(struct data_vio *data_vio);
+void vdo_clean_failed_hash_lock(struct data_vio *data_vio);
+void vdo_share_compressed_write_lock(struct data_vio *data_vio,
+				     struct pbn_lock *pbn_lock);
+
+int __must_check vdo_make_hash_zones(struct vdo *vdo, struct hash_zones **zones_ptr);
+
+void vdo_free_hash_zones(struct hash_zones *zones);
+
+void vdo_drain_hash_zones(struct hash_zones *zones, struct vdo_completion *parent);
+
+void vdo_get_dedupe_statistics(struct hash_zones *zones, struct vdo_statistics *stats);
+
+struct hash_zone * __must_check vdo_select_hash_zone(struct hash_zones *zones,
+						     const struct uds_record_name *name);
+
+void vdo_dump_hash_zones(struct hash_zones *zones);
+
+#endif /* VDO_DEDUPE_H */